People Also Ask
Cryolab has been specialising in cryogenic products and services since 2000, supplying IVF clinics, research labs, and biobanks across the UK and internationally. Our CryoNest® series of liquid nitrogen storage tanks offers stable −196 °C preservation with very low evaporation and highly organised internal racks with rapid dispatch, reliable customer service, and ISO‑certified quality, Cryolab is trusted for long-term sample storage.
Cryogenic storage dewars provide reliable LN₂ storage for a wide range of biological samples, including vials, straws, and cell cultures. They are compatible with various cryogenic racks and storage systems, allowing laboratories to organise samples efficiently and access them quickly. These dewars are designed to maximise laboratory space, reduce workflow time, and minimise sample exposure, ensuring long-term preservation of sensitive biological materials.
The market offers self-pressurising nitrogen storage dewars and a variety of dewar storage vessels suitable for research laboratories, fertility clinics, and biobanks. For laboratories seeking a high-performance, modern solution, the CryoNest series provides compact, safe, and efficient cryogenic storage. CryoNest tanks combine stability, durability, and user-friendly design, simplifying sample handling while maintaining ultra-low temperatures, making them ideal for high-throughput laboratories where sample safety and workflow efficiency are essential.
SpermScope® is designed for semen analysis and general cell counting. Labs also use it for blood samples, cell suspensions, tissue cultures, and bacterial observations. It gives consistent chamber depth, clear visibility, and reliable results for routine and diagnostic work.
A reusable sperm counting chamber is a precision laboratory device used to accurately count sperm cells for clinical, veterinary, or research applications. Cryolab’s SpermScope® is a high-quality, reusable chamber designed for both human and veterinary semen analysis. It features ultra-thin glass to reduce surface tension, a sealed aluminium frame for durability, and a precision 10×10 grid for accurate cell counting. Each SpermScope® is individually serialised for full traceability, ensuring reliable results every time. Using SpermScope® helps labs maintain consistency, reduce errors, and improve workflow efficiency in semen analysis and related research.
CryoCan LN2 storage tanks are specifically designed to offer high-capacity cryogenic storage in a compact footprint, making them ideal for laboratories with limited space. Their lightweight and space saving design allows multiple tanks to be placed efficiently without overcrowding the lab, while still providing secure storage for vials, straws, and other cryogenic samples.
The tanks feature an integrated canister system, which organises samples for easy access, reducing workflow time and keeping the workspace orderly. This system also minimises the risk of sample exposure during retrieval, which is especially important in busy or high-throughput laboratory environments.
By combining compact design, modular storage options, and reliable ultra-low temperature performance, CryoCan tanks enable laboratories to maximise available space without compromising sample integrity. They are suitable for a variety of settings, from fertility clinics to research laboratories and biobanks, offering efficient, organised, and safe cryogenic storage even when laboratory space is at a premium.
CryoCan vessels are designed for long-term, static storage of biological samples in liquid nitrogen. They’re lightweight, space-efficient, and built from high-strength aluminium alloy, making them easy to handle without compromising durability.
The most popular models are the CryoCan 30-6, CryoCan 47-6, and CryoCan 47-10. All three offer exceptionally low LN₂ consumption and outperform well-known 47-litre tanks in holding time and overall efficiency.
Every CryoCan includes UKCA and CE marking, a 5-year vacuum warranty, a 2-year parts warranty, and round canisters as standard. Roller bases are also available. Smaller custom sizes from 3 to 25 litres, plus a 35-litre six or ten-canister model, are available on request.
CryoStork dry shippers keep samples frozen for 7 to 17 days, depending on the model.
Here’s the breakdown:
CryoStork V2 – up to 7 days
CryoStork V3 – up to 9 days
CryoStork V4 – up to 9 days
CryoStork V6 – up to 11 days
CryoStork V10 – up to 17 days
These durations come from each model’s LN₂ absorption capacity and static evaporation rate. All units store samples in the vapour phase, ensuring a dry, spill-free shipment while maintaining ultra-low temperatures throughout transport.
- Protective gear: Always wear insulated gloves, a lab coat, and eye or face protection to prevent frostbite or splashes.
Upright position: Keep dewars upright and stable at all times. Never tilt, roll, or drop them.
Avoid direct contact: Never touch liquid nitrogen or cooled surfaces with bare skin. Even brief contact can cause severe frostbite.
Proper ventilation: Work in well-ventilated areas to prevent oxygen displacement, which can create a suffocation risk.
Careful transport: Use carts or carriers for heavy dewars. Avoid lifting large dewars manually unless they are designed for it.
Slow handling: Pour or transfer liquid nitrogen gradually to minimise splashing and rapid gas expansion.
Secure lids correctly: Keep lids slightly ajar to allow nitrogen gas to vent; never seal completely.
Keep flammables away: Liquid nitrogen can make nearby materials extremely cold and brittle. Keep flammable or reactive materials at a safe distance.
Monitor levels: Check nitrogen levels regularly to ensure samples remain at stable temperatures.
Emergency preparedness: Know the location of safety showers, eye wash stations, and first aid kits in case of exposure.
When choosing the right dry shipper size, one should first consider the total number and type of samples that need to be transported. Estimating the volume accurately ensures the dry shipper is neither too small (risking overcrowding) nor unnecessarily large (wasting space and cooling efficiency). Next, evaluate the expected duration of transport. Longer shipping times require a larger or higher-capacity dry shipper with superior thermal retention. Portability and handling are also important the ideal dry shipper should be easy to carry while maintaining sample safety.
Cryolab’s CryoStork® dry shippers provide a range of sizes and capacities, designed to meet different sample volumes, transport durations, and handling needs. By matching the sample load, travel time, and handling requirements to the appropriate CryoStork® model, one ensures safe, efficient, and compliant transport of biological samples.
Selecting the right cryo tank is essential for safe, efficient storage of biological samples. Consider the storage capacity, number of compartments, internal rack system, and ease of sample access to ensure optimal workflow and prevent overcrowding.
The CryoNest® XL cryogenic tank from Cryolab provides secure long-term preservation of samples in liquid nitrogen. With six internal racks offering up to 24 compartments, it keeps samples organised and easily accessible. Its 95-litre capacity and compact design (H: 790mm x W: 678mm) make it ideal for laboratories and veterinary facilities requiring reliable, traceable, and efficient cryogenic storage.
Cryolab Stainless Steel Open Dewars are designed for the safe handling, decanting, and short-distance transport of liquid nitrogen in laboratories, IVF clinics, and research facilities. They provide a durable and reliable solution for moving liquid nitrogen between storage tanks, workstations, or equipment, supporting routine cryogenic workflows while ensuring laboratory safety and efficiency. These dewars allow controlled pouring, temporary holding of liquid nitrogen, and easy integration with canister systems for short-term handling during experiments or clinical procedures.
CryoCrest 35 features advanced vacuum insulation and an efficient design to reduce liquid nitrogen evaporation. This minimises LN₂ loss over time, making storage more economical and safer for long-term cryogenic applications.
Yes, Cryolab offers Minitube Storage Cassettes that are specifically designed for efficient and organised cryogenic sample management. These cassettes come in flat and triangular designs, in short and long lengths, and are available in multiple colours—green, blue, yellow, red, white, and beige—making it easy to identify and sort samples quickly.
For efficient sample organisation, colour-coding and cassette shape are key. Flat cassettes are ideal for straightforward handling and retrieval of vials or straws, while triangular cassettes maximise storage density within liquid nitrogen tanks, helping laboratories make the most of limited space.
Made from durable, cryogenic-grade plastic, Minitube Cassettes withstand repeated exposure to ultra-low temperatures without cracking or degrading. They integrate seamlessly with, CryoCan Canisters, CryoNest Canisters and standard cryogenic racks, supporting high-throughput workflows in fertility clinics, research laboratories, and biobanks. By keeping samples upright, separated, and clearly colour-coded, these cassettes reduce handling errors, improve retrieval times, and make cryogenic sample management safer and more efficient.
A vitrification kit, or Vit Kit, is a complete set of tools and consumables used for the rapid cryopreservation of biological samples such as oocytes and embryos. It enables ultra-fast cooling to prevent ice crystal formation, ensuring high survival rates during storage in liquid nitrogen. Cryolab’s CBS High-Security Vitrification Kits are designed for precise, safe, and efficient handling, compatible with our cryogenic storage solutions such as cryocanes, cryosleeves, and visotubes, making them ideal for IVF clinics, research laboratories, and biobanking applications.
Sperm straws are specialised tubes designed for the safe collection, storage, and cryopreservation of semen samples. They are typically made from durable materials such as sterile PETG or high-security options to withstand extreme cold in liquid nitrogen. At Cryolab, our CBS High-Security and CBS Sterile Sperm Straws integrate seamlessly with cryocanes, cryosleeves, and visotubes, ensuring organised storage and easy identification of samples. These straws are ideal for IVF clinics, research facilities, and animal breeding programs, providing reliable sample preservation with minimal risk of contamination.
A sterile filling nozzle ensures precise, contamination-free manual filling of CBS High Security Sperm Straws, making it essential for the safe cryopreservation of delicate biological samples. Using the correct filling nozzle helps maintain sample integrity, reduces the risk of contamination, and ensures consistent results during storage. Cryolab’s sterile filling nozzles are specifically designed to work with high-security straws and cryogenic storage systems, providing laboratories with a reliable and efficient tool for long-term cryogenic preservation.
CBS Daisy Goblets with Visotubes provide a secure and organised method for freezing and storing biological samples in straws. Each pre-built daisy goblet contains 11 triangular visotubes, one clear round visotube, and a clear cover, offering efficient sample management. With a total height of 135 mm, they can hold up to 540 PETG 0.25 ml straws, 240 PETG 0.5 ml straws, or 168 CBS High Security Straws. Designed for compatibility with cryogenic canisters, Daisy Goblets help laboratories maintain traceability, reduce handling errors, and ensure safe, long-term cryopreservation of delicate samples.
When working with liquid nitrogen, dry shippers, or cryogenic storage vessels, choosing the right cryogenic gloves is crucial for safety and efficiency. Cryolab offers premium cryogenic gloves designed to protect against extreme cold while maintaining dexterity for precise laboratory tasks. Our gloves feature multi-layer insulation, superior thermal resistance, and durability, making them ideal for IVF clinics, research labs, and biobanks. Using high-quality cryogenic gloves from Cryolab ensures safe handling of LN₂, reduces the risk of frostbite, and supports compliance with laboratory safety standards.
Efficient sample organisation in a cryogenic tank is essential for laboratories, IVF clinics, and veterinary facilities. Using the right cryosleeves, cryocanes, and coders ensures your samples remain upright, secure, and easy to identify.
Cryolab’s cryosleeves and cryocanes are designed to fit all standard cryogenic tanks, while colour-coded coders improve traceability and reduce errors during sample handling. Together, these accessories maximise storage efficiency, maintain sample integrity, and streamline lab workflows.
Cryolab supplies Brady labels and compatible printers designed for accurate and durable sample identification in cryogenic conditions. These labels withstand liquid nitrogen exposure, moisture, and temperature fluctuations, making them ideal for IVF clinics, research labs, and biobanks. Using Brady labels with Cryolab’s cryogenic storage systems (like CryoNest® tanks, CryoStork® dry shippers, and visotubes) ensures traceability, compliance, and workflow efficiency. Visit Cryolab to explore a range of label sizes and printers suited for all lab applications.
Cryo markers are essential for labelling cryogenic vials, straws, and other biological samples. At Cryolab, we supply high-quality cryo markers designed to withstand extreme temperatures without smudging or fading. These markers are perfect for use with CBS High Security Straws, Visotubes, CryoCanes, and other cryogenic storage systems. You can order them directly from Cryolab’s online store to ensure reliable, long-lasting identification of your valuable samples.
Yes. Cryolab supplies Brady label printers and compatible labels designed specifically for cryogenic laboratories. This includes models such as the BMP21, BMP51, and TLS2200, all built to deliver durable, high-quality labels that withstand liquid nitrogen, extreme temperatures, moisture, and repeated handling.
These printers are ideal for labelling cryogenic storage vessels, vials, straws, and other sample containers, helping maintain accurate sample identification and traceability.
Using Brady printers and labels from Cryolab helps laboratories reduce labelling errors, improve workflow efficiency, and keep samples organised. Labels adhere securely, resist smudging or peeling, and remain legible after repeated freeze thaw cycles, making them an essential tool for IVF clinics, biobanks, and research laboratories.
Storage canisters are specialised containers used inside liquid nitrogen dewars and cryogenic tanks to organise and store biological samples. They keep vials, tubes, or cryo straws neatly arranged while maintaining ultra-low temperatures. Cryolab’s storage canisters are designed for labs, fertility clinics, and biobanks that need reliable, organised cryogenic storage.
Cryolab is a trusted supplier of laboratory consumables across the UK. Their CryoNest® range is designed for reliability, efficiency, and safety, supporting fertility clinics, research labs, and biobanks. Explore the full range at www.cryolab.co.uk
Effective sperm cryopreservation requires precise handling and consistent ultra-low temperature conditions. Cryolab supplies everything needed to support this process, from cryogenic storage tanks and portable liquid nitrogen dewars to storage canisters that keep samples organised. Their reusable manual observation chambers allow technicians to monitor sample quality in a structured field of view, ensuring reliable results without disposable waste. Cryolab’s solutions are designed to optimise lab workflows, enhance sample safety, and support high standards of reproductive and research practice. By using Cryolab equipment, fertility clinics, biobanks, and research laboratories across the UK can trust that sperm samples are preserved safely, efficiently, and sustainably.
Cryotubes and Cryovials are designed for secure storage of biological samples, including sperm, embryos, and other sensitive materials. They are engineered to withstand ultra-low temperatures in liquid nitrogen or cryogenic dewars, providing sterile, leak-proof, and hermetically sealed protection. Available in multiple sizes like 2 ml and 5 ml, they are compatible with standard cryogenic racks, labels, and laboratory workflows for IVF, veterinary, and biomedical research.
Cryolab Minitube Storage Cassettes are used to organise and store cryogenic vials and straws efficiently in liquid nitrogen tanks. Flat and triangular designs allow for colour-coded grouping, easy sample identification, and maximised tank space. They help laboratories maintain sample accessibility, prevent mix-ups, and optimise workflow for IVF, veterinary, and biomedical research applications.
A laboratory equipment suppliers provide essential tools, instruments, and consumables used in medical, research, and industrial laboratories. This can include cryogenic storage systems, lab consumables, safety equipment, and accessories. Cryolab is a specialist laboratory equipment supplier offering cryogenic and IVF-related solutions for clinics, hospitals, and research facilities.
When choosing a laboratory equipment supplier, it’s important to consider product quality, certifications, after-sales support, and industry experience. Suppliers like Cryolab work closely with laboratories and IVF centres to ensure equipment meets safety standards and long-term storage requirements.
Scientific lab supplies are used in laboratories for research, diagnostics, and medical applications. These include consumables, storage solutions, and handling tools required for daily lab operations. Cryolab provides scientific lab supplies that support cryogenic storage and sample preservation in IVF and research environments.
Cryogenic tanks are used to store biological samples at ultra-low temperatures using liquid nitrogen. They are commonly used in IVF clinics, hospitals, and research labs for preserving embryos, sperm, oocytes, and cell samples. Cryolab supplies cryogenic tanks designed for safe, long-term storage.
Keeping cryogenic samples safe requires using reliable sealing systems and proper laboratory protocols. Systems like the CBS SYMS I and SYMS III sealers are specifically designed to provide airtight and secure seals for high security straws and tubes. Properly sealed samples are protected from environmental exposure, contamination, and leakage, which are major risks during long-term storage in liquid nitrogen.
In addition to sealing, careful handling, correct storage temperatures, and regular monitoring of tanks are essential to maintain sample viability. Using spare sealing components ensures that laboratories can operate efficiently and consistently, even when handling many samples at once. This combination of secure sealing and strict procedural adherence allows fertility clinics, research labs, and cryobanks to maintain sample integrity, ensuring that sperm, oocytes, embryos, or other biological materials remain safe, viable, and ready for use whenever needed.
The best way to store biological samples in Cryotubes is to ensure each tube is sterile, properly sealed, and kept in controlled cryogenic conditions. Handling Cryotubes carefully prevents contamination and maintains the quality of sperm, oocytes, embryos, or other sensitive materials. Laboratories often use sealing equipment to create airtight closures, which helps preserve the integrity of samples over long-term storage in liquid nitrogen.
Using Cryotubes in appropriately sized packs allows labs to manage both small and large volumes efficiently, while ready-to-use tubes reduce preparation time and streamline workflow. Proper lab practices, combined with high-quality Cryotubes, help maintain sample viability, improve reproducibility in experiments, and provide confidence that materials remain safe for future clinical or research use.
Labs use goblets for storing straws and vials because they provide organised, secure, and efficient storage in cryogenic tanks. Goblets help maintain samples at ultra-low temperatures, preventing contamination or degradation of sperm, embryos, stem cells, and other biological materials. The design of cryogenic goblets allows for easy identification and retrieval of individual straws or vials, reducing handling errors and improving workflow efficiency.
Made from durable, cryo-resistant materials, goblets withstand repeated freezing and thawing cycles, ensuring consistent protection of valuable samples. Using goblets in IVF clinics, biobanks, and research laboratories supports reproducibility in experiments, long-term sample preservation, and reliable laboratory operations, giving staff confidence that all biological materials remain safe and intact over time.
Labs use Brady printers and labels for sample tracking because they provide durable, accurate, and easy-to-read identification for vials, tubes, and storage containers. Clear labelling is critical to prevent sample mix-ups, maintain integrity, and support reproducibility in experiments and clinical procedures.
Brady labels are designed to withstand harsh conditions such as freezing, moisture, and chemical exposure, making them ideal for cryogenic storage and laboratory environments. With Brady printers, staff can quickly create custom labels for different sample types and storage systems, streamlining workflow and reducing errors. Using reliable labelling systems ensures that biological materials remain correctly identified, enhances safety and compliance, and gives laboratories confidence in long-term storage and tracking processes.
Brady Labels are high-quality, durable labels designed to withstand extreme temperatures, including those found in cryogenic laboratories. These labels are ideal for marking cryogenic vials, storage tanks, and sample containers, ensuring that sample identification remains clear even when exposed to liquid nitrogen or ultra-low freezers. Unlike standard paper labels, Brady Labels are resistant to smearing, peeling, and fading, making them perfect for labs handling IVF, research, or clinical samples. At Cryolab, we recommend using Brady Labels with our Cryomarker Fine Tip for precise labelling, or in combination with automated label printers for consistent, professional results. By incorporating Brady Labels into your workflow, laboratories can reduce human error, maintain compliance with safety standards, and protect the integrity of sensitive samples.
While ultrasonic and cryogenic level sensors provide continuous monitoring, a Dipstick offers a reliable manual backup for liquid nitrogen measurement. It allows lab staff to quickly verify storage levels, ensuring Cryogenic laboratory gloves can be used safely without risking sample exposure. Manual readings act as a safeguard against sensor failure or calibration errors. Using a dipstick alongside automated systems enhances sample integrity, prevents accidental thawing, and supports lab safety protocols. At Cryolab, we advise integrating dipsticks into all cryogenic workflows for redundancy, accuracy, and peace of mind.
Open Dewars are specialised containers designed for storing and handling liquid nitrogen in cryogenic laboratories. Unlike closed dewars, which are sealed to minimise evaporation, open dewars provide easy and quick access to samples, making them ideal for laboratories where frequent sample retrieval is required. They are widely used in research facilities, IVF clinics, clinical labs, and other cryogenic applications where maintaining ultra-low temperatures is essential.
The design of an open dewar allows vials, tubes, and other cryogenic materials to be safely and efficiently inserted or removed without disturbing the remaining liquid nitrogen. Open dewars come in various sizes and volumes, enabling labs to choose the best option for their workflow and storage requirements.
One key advantage of open dewars is their ability to simplify sample organisation. Technicians can quickly sort and access multiple samples, reducing handling time and minimising the risk of accidental warming or contamination. Additionally, open dewars are often lightweight and portable, which makes them convenient for transferring samples between storage areas or equipment.
By using open dewars, laboratories can maintain consistent ultra-low temperatures, protect sample integrity, and improve operational efficiency. Many labs combine open dewars with proper labelling systems, such as cryogenic markers or durable labels, to ensure samples are easy to identify and manage. Overall, open dewars are an essential tool for any lab dealing with cryogenic storage and handling, balancing accessibility with reliable temperature maintenance.
Remote monitoring transforms sample safety by providing 24/7 oversight of tank conditions. Cryolab Monitoring System continuously logs LN2 levels, internal temperature, and alarm events, allowing lab personnel to address deviations before samples are compromised. This proactive approach not only minimises risk but also supports compliance with IVF regulatory standards, ensuring embryos, oocytes, and sperm are always stored under optimal conditions.
cryogenic storage tank alarm is a critical alert signalling potential risk to your biological samples. Most commonly, it is triggered by low liquid nitrogen levels, temperature fluctuations, or sensor errors. Cryolab’s advanced CryoNest tanks paired with the Cryolab Monitoring System allow laboratories to detect issues early, track LN2 levels remotely, and receive real-time alerts. By using Cryolab’s monitoring solution, labs can prevent sample warming, ensure consistent cryogenic conditions, and respond immediately to alarms before any damage occurs.
Yes. Closed system CBS vit kits protect embryos and oocytes from direct LN2 contact, contamination, and thermal fluctuations. Cryolab’s CBS straws are designed for high reproducibility and consistent results, significantly reducing vitrification failure rates while enhancing laboratory efficiency and clinical outcomes.
Only cryogenic-rated labels, such as Brady labels, are suitable for LN2 conditions. Standard adhesives and inks fail under extreme cold, causing peeling, fading, or loss of legibility. Brady labels maintain adhesion, resist moisture, and remain readable even after long-term storage in Cryolab CryoNest tanks, ensuring samples are traceable and compliant with IVF standards.
Yes. Best practices include labelling straws before cryopreservation, including patient ID, sample type, and date, using colour-coded and barcoded Brady labels, and verifying legibility before placing samples into Cryolab LN2 storage tanks. Consistent adherence to these practices improves workflow efficiency, compliance, and overall safety in high-volume IVF laboratories.
CryoStork range of dry shippers is specifically designed for safe international transport of IVF samples including embryos, oocytes and sperm. CryoStork dry shippers are IATA approved for air freight, maintain cryogenic temperatures for up to 10 days without LN2 top-up, and are available in multiple capacities including 1 litre, 3 litre and larger models. They are used by IVF clinics and fertility laboratories worldwide for secure biological sample transport.
Choose a 20 litre liquid nitrogen dewar if you need a manageable working vessel for daily LN2 handling, topping up storage tanks or short term sample storage. Choose a 35 litre dewar – CryoCan 30-6 if you need longer static hold times between refills and have higher sample volumes. The 35 litre offers a better volume-to-surface-area ratio meaning LN2 evaporates more slowly, reducing running costs and refill frequency for busy laboratories.
Vitrification warming solution is the first solution the vitrified sample contacts during the warming protocol. It rapidly rehydrates the cell and begins removing cryoprotectants. The warming solution is pre-heated to 37°C before use rapid temperature transition from -196°C is critical to prevent recrystallisation. After the warming solution the sample moves through a series of dilution solutions to gradually restore normal osmotic balance before transfer or assessment.
No. Denudation pipettes are specifically designed for removing cumulus cells from oocytes and are not suitable for embryo transfer. Embryo transfer requires dedicated embryo transfer catheters with specific tip designs for atraumatic uterine placement. Denudation pipettes are used exclusively in the IVF laboratory for oocyte preparation before ICSI, not for clinical procedures.
Sperm cryopreservation typically uses glycerol-based cryoprotectant solutions, often combined with egg yolk or soy lecithin as membrane protectants. Unlike oocyte vitrification which uses ethylene glycol and DMSO, sperm cryopreservation uses lower cryoprotectant concentrations with a slower controlled rate freezing protocol. The cryoprotectant is mixed with the sperm sample before loading into CBS High Security Sperm Straws and cooling in a controlled rate freezer or LN2 vapour. Visit Cryolab today.
A complete sperm cryopreservation setup requires five core pieces of equipment and consumables.
A sperm analysis system for pre-freeze assessment. Glycerol-based cryoprotectant solution for sample preparation. High security sperm straws for loading the sample. A controlled rate freezer or liquid nitrogen vapour rack for the cooling process. A cryogenic storage dewar for long-term preservation at minus 196 degrees Celsius.
Post-thaw analysis equipment is also required to assess recovery rates before clinical use.
20 litre liquid nitrogen dewar typically holds its charge for between 30 and 90 days depending on the model, neck diameter, insulation quality and how frequently it is opened. Narrow-neck models retain liquid nitrogen longer because the smaller opening reduces evaporation losses. Static storage dewars with minimal access requirements will outperform vessels opened frequently for sample retrieval. Always check the manufacturer’s static evaporation rate specification when comparing models. Cryolab supplies the CryoCan and CryoNest range with specifications suited to IVF and research laboratory requirements.
View the full 20 litre liquid nitrogen dewar buying guide at cryolab.co.uk/20-litre-liquid-nitrogen-dewar-buying-guide/
Oocyte vitrification uses a two-step cryoprotectant protocol. An equilibration solution containing lower concentrations of cryoprotectants is applied first to allow gradual cell dehydration. A vitrification solution with higher cryoprotectant concentrations — typically a combination of DMSO and ethylene glycol — is then applied immediately before the sample is plunged into liquid nitrogen. Validated kits with matched equilibration and vitrification solutions reduce variability between laboratory sessions. CBS HSV Vitrification Kits provide a complete closed system with both solutions included. Full guide to cryoprotectant solution in IVF at cryolab.co.uk/complete-guide-oocyte-vitrification-uk/
IVF laboratories in the UK can source cryogenic supplies and consumables from specialist cryogenic equipment suppliers. Key items to source from a single supplier where possible include storage straws, goblets, canisters, cryocanes, visotubes, vitrification kits, cryogenic safety wear and storage vessels. Consolidating supply reduces administration and supports consistent quality across consumable categories. Cryolab has supplied IVF laboratories and research facilities across the UK since 2000, holding ISO 9001:2015 certification. The full range of cryogenic laboratory supplies and consumables is available at cryolab.co.uk
Choosing the right cryogenic storage vessel depends on four factors: capacity required, access frequency, available floor space and static evaporation rate. High-volume programmes with large sample banks need vessels with greater capacity and high-density internal organisation. Laboratories with limited space benefit from compact footprint designs that maximise storage within a smaller floor area. Programmes with frequent sample retrieval need wider-neck vessels for easier access. Static evaporation rate determines how often the vessel needs topping up with liquid nitrogen a lower rate reduces maintenance frequency. CryoNest vessels from Cryolab offer large capacity with compact footprint for busy IVF programmes. CryoCan vessels suit smaller laboratories or satellite storage requirements.
Full guide to storage vessel selection at cryolab.co.uk/20-litre-liquid-nitrogen-dewar-buying-guide/
Embryos are loaded into labelled storage straws typically CBS Embryo Straws in 0.15ml or 0.3ml formats after vitrification or slow freezing. Each straw is sealed, labelled with patient and sample details and placed into a CBS Daisy Goblet, which holds multiple straws in a high-density arrangement. Goblets are placed inside CBS Canisters, which slot into the internal canes of the storage vessel. This hierarchical organisation straw, goblet, canister, vessel allows efficient use of storage space and reliable sample retrieval without disturbing other samples in the vessel. Cryolab supplies CBS Embryo Straws, CBS Daisy Goblets and CBS Canisters for IVF laboratory vessel storage. View the full range at http://cryolab.co.uk
Most IVF units storing 500-2000 embryo straws operate effectively with a 30-47 litre dewar. This provides 3-5 months between refills whilst maintaining safe working temperatures. Smaller practices managing under 500 straws can use 20L vessels. Contact us today visit Cryolab
A quality 20 litre liquid nitrogen dewar with proper vacuum insulation holds nitrogen for 60-90 days when kept sealed. Opening frequency dramatically affects this laboratories accessing samples multiple times daily may see 40-50 day hold times. Static evaporation rates under 0.3L/day indicate good vacuum performance. Always monitor levels weekly using a cryogenic dipstick rather than relying on manufacturer estimates.
Vitrification uses ultra-rapid cooling (>20,000°C/minute) with high-concentration cryoprotectants, creating a glass-like state that prevents ice crystals. Slow freezing gradually reduces temperature whilst removing water, but often causes intracellular ice damage. Vitrification survival rates for mature oocytes now exceed 90% compared to 50-70% with controlled-rate freezing. The technique requires specialised carriers like the CBS HSV kits and precise warming protocols.
Professional dewar nitrogen storage follows a canister-cane-straw hierarchy. Straws containing individual samples load onto numbered canes (10-12 per cane), which then slide into colour-coded canisters. Each canister occupies one dewar position. This system enables rapid sample location without extended lid-open time that causes nitrogen boil-off. Always maintain an electronic inventory tracking exactly which cane holds each patient sample.
UK veterinary practices typically use 20-35 litre liquid nitrogen dewars for bovine semen storage. CryoCan 30-6 offers an excellent balance 30L capacity holding 2,000+ straws across six canisters, with 70-day static hold time. CBS High Security straws prevent contamination through heat-sealed ends. Larger AI centres managing 5,000+ doses require 47L models with ten-canister organisation for easier inventory management.
Validating vitrification warming requires demonstrating >85% oocyte survival and normal morphology post-thaw. Protocol timing is critical—immerse the carrier in 37°C warming solution within 2 seconds of removing from liquid nitrogen. Extended air exposure allows ice crystallisation. Assess membrane integrity immediately using fluorescent dyes, then culture surviving oocytes for 2-4 hours before insemination. Document survival rates per operator to identify training needs. cryolab.co.uk
IVF embryos are transported in cryogenic dry shippers specialised LN2-absorbent vessels that maintain -196°C without liquid nitrogen being present, complying with IATA transport regulations.
The right liquid nitrogen storage vessel for an IVF laboratory depends on three things: the number of samples you store, how frequently you access them, and how much floor space you can realistically allocate.
For smaller clinics or satellite labs say, under 500 patients in active storage a 20 litre liquid nitrogen dewar or a CryoCan 30-6 covers the volume without creating a storage management problem. These vessels are lightweight, easy to move, and simple to maintain. Hold times on the CryoCan 30-6 are significantly better than most comparable 20L options, which reduces the frequency of refills and the associated handling risk.
For mid-volume clinics running 500 to 2,000 patients in active storage, CryoCan 47-6 or CryoCan 47-10 is the step up that makes sense. 47-litre capacity with six or ten canisters gives you the organised structure that high-volume retrieval needs, you are not digging through a tank, you are lifting a specific canister.
For large IVF units, hospital cell banking programmes, or research-scale biobanks, CryoNest series (XL at 95 litres, XXL, and XXXL at 175 litres) provides the high-capacity vessel storage that standard dewars cannot match. The internal rack system in the CryoNest gives up to 30 compartments in the XXXL, which transforms sample organisation at scale.
The common mistake is buying for current volume rather than projected volume. A vessel that is right today but forces you to add a second tank in 18 months is not efficient it doubles your maintenance overhead and your nitrogen costs.
Browse the full liquid nitrogen storage vessel range at https://cryolab.co.uk/product-category/storage-vessels/
An oocyte vitrification carrier is the device that holds an egg (or embryo) during the critical moment of ultra-rapid cooling — the plunge into liquid nitrogen that defines vitrification. The carrier needs to be designed for maximum heat transfer speed, minimal media volume, and secure, identifiable storage immediately after loading.
CBS High Security Vitrification Kit addresses all three. The carrier consists of a capillary tube with a pre-formed gutter that positions the sample precisely, co-injected with a coloured handling rod for immediate visual identification. The colour coding is not decorative in a busy IVF laboratory during a retrieval session, being able to identify a carrier instantly by colour reduces handling time and error risk simultaneously.
Once loaded, the straw is sealed using the CBS SYMS sealer, creating an airtight, tamper-evident closure compatible with long-term storage in cryocanes, visotubes, and CBS canister systems.
Cryoprotectant solution used in vitrification is loaded onto the carrier before the plunge. The capillary gutter design is compatible with standard vitrification media protocols and minimises the volume of cryoprotectant solution required per sample, which matters for labs managing costs at scale.
Vitrification warming protocol uses the CBS High Security Vitrification Straws Opening Device to cut and open the sealed straw cleanly without physical stress to the sample during thawing. This is a step that is sometimes done with scissors or improvised tools in lower-spec labs, which introduces unnecessary risk.
Full CBS High Security Vitrification Kit details at https://cryolab.co.uk/product/vit-kit/
Cryogenic gloves for laboratory use are not all equivalent, and choosing the wrong length for a specific task creates a genuine safety risk rather than just an inconvenience.
The four lengths Cryolab supplies each correspond to different task risk profiles:
Wrist-length cryogenic gloves suit brief, controlled handling tasks where the risk of splash or immersion is low — picking up a cold surface, handling a sample briefly above the tank. They are not appropriate for filling operations or deep vessel access.
Mid-arm length is the standard for most routine IVF laboratory liquid nitrogen work — canister access, cryocane retrieval, brief filling of smaller vessels. This length covers the most common gap between glove cuff and sleeve that causes the most frostbite incidents.
Elbow-length gloves are appropriate when reaching into deeper vessels, handling larger canister configurations, or working at a tank opening that requires an extended reach. Labs running CryoNest XXXL vessels or large MVE storage systems will typically have at least some elbow-length gloves in use.
Shoulder-length gloves are for filling operations from bulk supply dewars, immersion tasks, or any procedure where the full arm could come into contact with liquid nitrogen or extremely cold surfaces. These are mandatory for anyone operating a liquid nitrogen dispensing system regularly.
Face shield question matters equally. A liquid nitrogen face shield particularly the full face shield with chin guard that Cryolab supplies is the appropriate PPE for filling and dispensing, not just a goggle.
Full safety wear range including all cryogenic glove lengths and face shields at https://cryolab.co.uk/product-category/safety-wear/
A liquid nitrogen dewar and a liquid nitrogen storage vessel are terms often used interchangeably, and in most biological and clinical contexts they refer to the same type of equipment: a vacuum-insulated container designed to hold liquid nitrogen at −196°C for the safe preservation of biological samples. The distinction, where one exists, tends to be in scale and application.
The term ‘dewar’ originates from the scientist James Dewar, who developed the vacuum-insulated flask in the 19th century. In modern laboratory use, ‘dewar’ is typically used for smaller, non-pressurised vessels — ranging from a few litres to around 50 litres used in biological storage, sample handling, and transfer. A ‘storage vessel’ or ‘cryogenic storage vessel’ is often used to describe larger, purpose-built systems designed for high-capacity, long-term static storage, particularly in IVF clinics, biobanks, and research institutions.
In practice, both terms describe the same class of equipment. What matters when choosing between products is not the terminology but the specifications: capacity, hold time, internal organisation system, insulation quality, and compliance certifications such as UKCA and CE marking. Cryolab’s CryoCan Series (30–47 litres) and CryoNest® Series (95–175 litres) cover both ends of this spectrum compact canister-based dewars and high-capacity racked storage vessels all to the same quality standard.
See the full range at cryolab.co.uk/product-category/storage-vessels/
Refill frequency for a liquid nitrogen storage dewar depends primarily on the vessel’s capacity, its static hold time, and how frequently the vessel is accessed. A 20-litre liquid nitrogen dewar with good vacuum insulation and a narrow neck will typically hold liquid nitrogen for 60–90 days under static conditions meaning unopened and undisturbed. In active clinical use, where the vessel is opened multiple times daily for sample retrieval, that figure can reduce to 40–50 days or fewer.
Larger vessels hold nitrogen proportionally longer. A 47-litre dewar with an efficient insulation design such as the Cryolab CryoCan 47-10 can maintain LN2 levels for well in excess of 70 days under static conditions and significantly longer than comparable models on the market. High-capacity vessels like the Cryolab CryoNest® Series (95–175 litres) dramatically reduce refill frequency for busy clinics: more volume, lower evaporation rate, and fewer interruptions to clinical workflow.
As a practical guide for IVF and biological research settings: units storing 500–2,000 samples in a 30–47 litre dewar should plan for a refill every 6–10 weeks under normal access conditions. Larger operations using 95–175 litre vessels can extend that to 3–5 months between refills, depending on daily access. Monitoring LN2 levels weekly and maintaining a refill schedule before levels drop below the recommended minimum is best practice for any biological storage environment.
For advice on matching refill frequency to your workflow, contact Cryolab at info@cryolab.co.uk or explore the range at cryolab.co.uk
Yes, embryos and sperm can be stored in the same liquid nitrogen vessel, provided the vessel has an adequate internal organisation system to keep different patient samples clearly separated and consistently identifiable. In IVF practice, it is common for clinics to store multiple sample types embryos, oocytes, and sperm within a single high-capacity vessel, using a structured canister and rack system to maintain clear segregation and traceability.
The critical requirements are organisation, traceability, and thermal stability. Samples must be stored in clearly labelled, colour-coded, or individually identifiable containers typically CBS embryo straws, goblets, and canisters and the internal structure of the vessel must allow any individual patient’s material to be located and retrieved without disturbing adjacent samples. This is the core design principle behind both the Cryolab CryoNest® rack system and the CryoCan canister system.
Vapour-phase storage (where samples are held in nitrogen vapour at approximately −150°C to −190°C rather than submerged in liquid nitrogen) is increasingly preferred in high-volume IVF settings as it reduces the theoretical risk of cross-contamination between samples. The CryoNest® Series is designed to support both liquid and vapour-phase configurations. For clinics managing high patient volumes with mixed sample types, the CryoNest® XXXL (175 litres, up to 30 compartments) provides the organisation and capacity to manage a complex inventory safely and efficiently.
For specific guidance on storage configuration for your clinic’s patient volume and sample types, speak to the Cryolab team: info@cryolab.co.uk | cryolab.co.uk/product-category/storage-vessels/
Slow-cooling cryopreservation reduces the sample temperature gradually, which allows ice crystals to form inside cells despite cryoprotectant use, leading to lower survival rates, particularly in oocytes. Vitrification uses ultrarapid cooling at rates up to 20,000 degrees Celsius per minute, which causes intracellular water to transition directly to an amorphous glass-like state without crystal formation. This results in significantly higher oocyte and embryo survival rates, which is why vitrification has become the standard in clinical IVF.
Vitrified eggs are thawed using a validated warming protocol. The carrier holding the vitrified oocyte is removed from liquid nitrogen and the egg is immediately transferred to a warming solution at 37 degrees Celsius. It then moves through a series of dilution steps that progressively remove cryoprotectants while sucrose-buffered solutions manage the osmotic shift and prevent membrane damage. The process typically takes 10 to 15 minutes. The egg is then assessed for survival before proceeding to fertilisation.
The most commonly used cryoprotectants in oocyte vitrification include ethylene glycol (EG) and dimethyl sulphoxide (DMSO), typically used in combination. Sucrose is used in both the vitrification and warming solutions to create an osmotic buffer that helps manage the movement of water and cryoprotectants in and out of the cell. The specific concentrations and exposure times are defined by each kit’s validated protocol.
Clinical evidence and large-scale data from fertility programmes worldwide indicate that outcomes from vitrified eggs are comparable to fresh eggs in terms of fertilisation rates, embryo development, live birth rates, and the health of resulting children. Studies have found no increased risk of congenital abnormalities or developmental issues in children born following oocyte vitrification and warming. Regulatory bodies and major fertility organisations in the UK consider egg freezing using vitrification a clinically established, safe procedure.
Liquid nitrogen sits at -196 degrees Celsius. Any contact with skin or eyes causes instant cryogenic burns that can be severe and are often deceptively worse than they initially appear. The eyes are particularly vulnerable: even a small splash or vapour exposure can cause corneal injury and potential vision loss. Standard safety glasses do not provide sufficient protection because they do not cover the full face and can shatter at cryogenic temperatures. A full cryogenic face shield is required because it covers the entire face, wraps around to the sides, and is made from material rated for cryogenic environments.
In an IVF lab, working with liquid nitrogen requires a full-face cryogenic face shield, cryogenic gloves rated for liquid nitrogen temperatures, a long-sleeved lab coat, and closed-toe shoes as a minimum. Depending on the volume of liquid nitrogen handled, a cryogenic apron may also be appropriate. All PPE should be used consistently and paired with proper training and documented handling protocols. Cryolab supplies IVF safety wear for UK fertility labs.
When sperm cells are cryopreserved, they are first mixed with cryoprotectant agents that replace intracellular water. The sample is then cooled at a controlled rate to -196 degrees Celsius using liquid nitrogen. At this temperature, all metabolic activity stops completely and the cells enter a state of biological suspension. The cells remain in this state indefinitely and can be returned to normal function by thawing, provided the freezing and storage process was correctly managed
Extensive research and decades of clinical data show no increased risk of birth defects or health problems in children born from cryopreserved sperm compared to those conceived using fresh sperm. The freeze-thaw process does not cause genetic damage to sperm DNA in a clinically meaningful way when the process is properly conducted.
Sperm motility is measured in laboratory settings using either manual microscopy (a trained analyst counting sperm movement categories under a microscope) or Computer-Assisted Sperm Analysis (CASA) systems. CASA systems use high-speed cameras and tracking algorithms to classify sperm into WHO categories (progressive, non-progressive, immotile) and measure kinematic parameters including velocity and trajectory data. CASA is increasingly preferred for its reproducibility and consistency.
Sperm freezing refers to the technical cryopreservation process itself. Sperm banking is the broader practice of storing frozen sperm for future use, whether for personal fertility preservation, as part of a donor programme, or as an IVF backup. Sperm banking always involves sperm freezing, but sperm freezing is also performed outside of formal ‘banking’ contexts, such as creating a same-day backup sample before an IVF cycle.
A fully equipped andrology lab requires sperm analysis equipment (ideally a CASA system), a controlled-rate freezer or vapour-phase nitrogen protocol for cryopreservation, liquid nitrogen storage tanks, goblets and canes for organised sample storage, cryoprotectant reagents and consumables, appropriate PPE including liquid nitrogen face shields and cryogenic gloves, and a centrifuge for sample preparation. Cryolab supplies all of these to UK labs.
Sperm motility analysis is a component of semen analysis, not the same thing. A full semen analysis assesses volume, pH, sperm concentration, total sperm count, motility (in all three WHO categories), morphology, and viability. Motility analysis specifically evaluates movement patterns and is one of the most clinically significant parameters, particularly when assessing a sample for cryopreservation or IVF use.
Only a purpose-built cryogenic marker pen can truly withstand liquid nitrogen at -196°C. Regular permanent markers, even branded ones, will fade, smear or crack when exposed to LN2 immersion or deep-freeze storage. You need a pen with specially formulated waterproof, alcohol-resistant ink that stays bonded to the surface through extreme cold and repeated freeze-thaw cycles. Cryomarker Fine Tip – Black or Coloured – Pk4 is rated for cryogenic conditions and delivers clean, legible, permanent writing on cryovials, tubes, boxes, glass and metal exactly what labs, biobanks and IVF clinics need.
The best pen for labelling cryogenic vials is a fine-tip cryogenic marker with permanent, alcohol-resistant, waterproof ink that won’t fade at ultra-low temperatures. A fine tip matters because cryovials have minimal writing surface you need precision without ink bleed. The Cryomarker Fine Tip – Black or Coloured – Pk4 ticks every box: fast-drying, smudge-proof, compatible with LN2 (-196°C) and -80°C freezer environments, and available in both black and colour for easy sample colour-coding. It’s trusted by research labs, IVF clinics and biobanks for reliable, long-term sample identification.
Vitrification kit is a specialised set of laboratory consumables designed to facilitate the rapid freezing of biological samples, most commonly embryos, oocytes, sperm and other sensitive cellular material. The term vitrification refers to a process in which a biological sample is cooled at such an extreme rate that the water molecules within and around the cells do not have enough time to form ice crystals. Instead, the sample transitions into a glass-like, amorphous solid state, which is where the name vitrification originates, from the Latin word for glass.
The significance of this is enormous in the context of cryopreservation. Traditional slow-freezing methods, which were the standard for many decades, were associated with a well-documented risk of ice crystal formation during the cooling process. These ice crystals, however small, can cause physical damage to cell membranes and organelles, reducing the viability of the sample once it is thawed. Vitrification bypasses this problem entirely by eliminating the crystallisation phase altogether.
A vitrification kit typically contains a series of specialised carriers or devices on which the biological material is loaded, along with a set of cryoprotectant solutions that are applied to the sample before it is plunged into liquid nitrogen. The cryoprotectants work by replacing the water content within the cells with compounds that do not form damaging crystals, further protecting cellular integrity throughout the freezing and storage process.
In practice, a trained embryologist or laboratory technician will use a vitrification kit by first equilibrating the sample in a series of cryoprotectant solutions at controlled concentrations, then loading the sample onto the carrier device and plunging it directly into liquid nitrogen at approximately minus 196 degrees Celsius. The entire process from sample loading to liquid nitrogen immersion takes only a matter of seconds, which is what achieves the ultra-rapid cooling rate necessary for successful vitrification.
The CBS High Security Vitrification Kit from Cryolab is designed specifically to make this process as safe and reliable as possible for clinical and research laboratories across the UK. Its closed system design ensures that the sample is fully enclosed throughout the process, removing any risk of direct contact between the biological material and the liquid nitrogen itself.
For more information visit: cryolab.co.uk/product/vit-kit/
The difference between vitrification kits and slow freezing methods is fundamental, and it comes down to the speed at which biological samples are cooled, the technology used to achieve that cooling, and the outcomes that each approach produces.
Slow freezing, as the name suggests, involves cooling biological material at a controlled, gradual rate, typically using a programmable freezer that reduces the temperature by one or two degrees Celsius per minute. The process was the dominant method in reproductive medicine and cell biology for several decades and produced reasonable results. However, it has significant limitations. The primary problem is that the relatively slow cooling rate gives water molecules sufficient time to form ice crystals as the sample passes through the temperature range between zero and minus 60 degrees Celsius. These ice crystals can puncture cell membranes, disrupt organelles and cause irreversible structural damage that only becomes apparent when the sample is warmed and the cells are assessed for viability.
Vitrification works on an entirely different principle. Rather than controlling the speed of cooling with a machine, vitrification achieves its effect through the direct immersion of the sample into liquid nitrogen at minus 196 degrees Celsius. This creates a cooling rate that is many orders of magnitude faster than anything a programmable freezer can achieve, often in excess of 20,000 degrees Celsius per minute. At this speed, there is simply no time for ice crystals to form. The cellular water transitions directly into a solid, glass-like state without crystallising, leaving the cellular architecture intact.
The practical outcomes of this difference are significant. Studies across reproductive medicine have consistently demonstrated higher survival rates and better clinical outcomes with vitrification compared to slow freezing. Egg and embryo survival rates with quality vitrification kits now routinely exceed 90 percent in well-run clinical settings, which represents a substantial improvement over the figures historically associated with slow freeze protocols.
Vitrification kits have also simplified the laboratory workflow in many respects. The entire vitrification process can be completed in under 15 minutes per sample, compared to the several hours required for a full slow-freeze cycle. This makes it a more practical option for busy IVF units and research laboratories that need to process multiple samples efficiently.
The CBS High Security Vitrification Kit available from Cryolab combines the speed and efficacy of vitrification with a closed system design that adds an extra layer of biosafety not found in many conventional vit kit products. You can view the full product specification at cryolab.co.uk/product/vit-kit/
For more information visit: cryolab.co.uk/product/vit-kit/
Yes, vitrification kits are suitable for both embryo and oocyte storage, and in fact the widespread adoption of vitrification technology has been particularly transformative for oocyte cryopreservation specifically. For many years, the freezing of unfertilised eggs was considered technically unreliable, with survival rates low enough that it was not offered as a routine clinical option in many fertility centres. The introduction of high-quality vitrification kits changed this considerably.
Oocytes are notoriously challenging to cryopreserve. They are among the largest cells in the human body and have a high water content relative to their volume, which historically made them vulnerable to ice crystal formation during slow freeze protocols. Their large size also means they have a relatively low surface-area-to-volume ratio, which slows the rate at which cryoprotectants can penetrate the cell and replace the intracellular water before freezing. Vitrification addresses both of these challenges simultaneously. The ultra-rapid cooling rate prevents ice crystal formation regardless of the cell’s water content, and the concentrated cryoprotectant solutions used in vitrification protocols are highly effective at penetrating the oocyte membrane within the short equilibration windows that vitrification requires.
For embryos, vitrification kits have become the standard of care across most leading reproductive medicine centres globally. Both cleavage-stage embryos, which are typically two to three days post-fertilisation, and blastocysts, which are five to six days post-fertilisation, can be vitrified with excellent results using a quality vit kit. Blastocyst vitrification in particular has become the preferred approach in many programmes because the blastocyst stage allows for better embryo selection before freezing, and blastocysts respond exceptionally well to the vitrification process.
Beyond reproductive medicine, vitrification kits are also used in research settings to cryopreserve a wide range of cell types, tissue fragments, stem cells and other biological material. The CBS High Security Vitrification Kit from Cryolab is well-suited to both clinical and research applications across the UK. Its closed system design provides the additional biosafety features that regulated environments require.
For more information visit: cryolab.co.uk/product/vit-kit/
CBS High Security Vitrification Kit works by combining the established principles of ultra-rapid vitrification with a proprietary closed system carrier design that significantly enhances biosafety compared to conventional open-pull vitrification devices.
The process begins with sample preparation. The biological material, whether it is an embryo, oocyte or other cell type, is first placed into an equilibration solution containing cryoprotective agents. This step allows the cryoprotectants to begin penetrating the cell membrane and replacing the intracellular water with compounds that are far less susceptible to ice crystal formation. The sample is then moved through a series of increasingly concentrated cryoprotectant solutions in a carefully timed sequence, ensuring that the cells are adequately protected before the freezing step.
The key distinguishing feature of the CBS High Security system is its closed carrier. In an open vitrification system, the sample is loaded onto an exposed device and plunged directly into liquid nitrogen with no physical barrier between the biological material and the nitrogen itself. While this achieves the necessary cooling rate, it means the sample is technically in direct contact with the liquid nitrogen. Since liquid nitrogen is not sterile and can theoretically harbour biological contaminants from previously stored samples in the same tank, this creates a small but non-zero risk of cross contamination between samples stored in the same facility.
The CBS High Security Vitrification Kit eliminates this risk by enclosing the sample within a sealed protective outer structure before immersion in liquid nitrogen. The cooling rate achieved is still sufficient to produce full vitrification of the sample, because the materials used in the CBS carrier are designed to allow extremely rapid heat transfer despite the physical enclosure. The result is a vit kit that delivers the vitrification performance that laboratories need while meeting the biosafety standards that regulated clinical environments demand.
Once vitrified, samples stored in CBS High Security carriers can be retrieved from liquid nitrogen storage, warmed using an appropriate warming kit, and assessed for survival before use. The CBS system is compatible with standard cryogenic storage tanks and dewar systems, making it straightforward to integrate into existing laboratory workflows. Cryolab supplies the full CBS vitrification kit range to laboratories and clinics across the UK at cryolab.co.uk/product/vit-kit/
For more information visit: cryolab.co.uk/product/vit-kit/
The term high security in the context of a vit kit refers specifically to the biosafety characteristics of the carrier system used to hold the biological sample during and after vitrification. Not all vitrification kits are equal in this regard, and the distinction between open and closed system carriers is one of the most important considerations for laboratories operating in regulated clinical environments.
In a standard or open vitrification system, the biological sample is loaded onto an exposed carrier, such as a fine filament, a cryoloop or an open pulled straw, and then plunged directly into liquid nitrogen without any physical barrier protecting the sample from the nitrogen or from other materials present in the storage environment. This works well from a pure cooling-rate perspective, because there is no material between the sample and the liquid nitrogen to impede heat transfer. However, it introduces a potential biosafety concern.
Liquid nitrogen is not a sterile medium. It is possible, in theory, for microorganisms and viral particles to survive in liquid nitrogen, and for cross-contamination to occur between samples stored in the same dewar if those samples are held in open carriers. In a clinical IVF setting where samples from many different patients are stored in the same tank, this is a risk that regulatory frameworks in the UK and across Europe take seriously. Guidelines from bodies including the Human Fertilisation and Embryology Authority have increasingly emphasised the importance of closed system storage for clinical samples.
A high security vit kit addresses this by enclosing the sample within a sealed outer device before it is immersed in liquid nitrogen and placed into long-term storage. The CBS High Security Vitrification Kit from Cryolab achieves this through a proprietary sealed carrier system that provides complete physical separation between the sample and the storage environment, while still achieving the ultra-rapid cooling rates necessary for successful vitrification.
For any UK laboratory operating under HFEA or equivalent regulatory oversight, or for any research institution that takes sample integrity and cross-contamination prevention seriously, a high security vit kit is not simply a premium option. It is increasingly the expected standard. Cryolab supplies the CBS High Security Vitrification Kit to laboratories across the United Kingdom. Full details are at cryolab.co.uk/product/vit-kit/
For more information visit: cryolab.co.uk/product/vit-kit/
Vitrification kits can be purchased from a small number of specialist cryogenic laboratory suppliers in the United Kingdom. Because these are precision laboratory consumables used in clinical and research settings, they are not available through general laboratory supply catalogues and require a supplier with genuine expertise in cryopreservation products.
Cryolab is a UK-based supplier of cryogenic laboratory products, including the CBS High Security Vitrification Kit, which is one of the most widely respected closed system vit kit products available on the market. Cryolab supplies directly to IVF clinics, fertility centres, research institutions, biobanks and university laboratories across the United Kingdom and Ireland.
A closed system product such as the CBS High Security Vitrification Kit is the appropriate choice for most regulated environments. The second consideration is supplier knowledge. A good cryogenic supplier should be able to advise on the right product for your specific application, whether you are vitrifying human oocytes and embryos, animal reproductive material, stem cells or other biological samples.
The third consideration is supply reliability. For a busy fertility clinic or research programme, running out of vitrification kits is simply not an option. Working with a dedicated UK supplier like Cryolab means shorter lead times, direct communication and a supply chain that is not dependent on international shipping delays.
You can order CBS High Security Vitrification Kits directly from Cryolab by visiting cryolab.co.uk/product/vit-kit/ or by contacting the team at info@cryolab.co.uk
For more information visit: cryolab.co.uk/product/vit-kit/
One of the significant practical advantages of vitrification as a cryopreservation method is that, once a sample has been successfully vitrified and placed into liquid nitrogen storage, the duration of storage does not in itself affect the viability of the sample. This is because at minus 196 degrees Celsius, all biological activity within the cell is completely arrested. There is no metabolism, no oxidative stress, no cellular degradation. The sample exists in a state of suspended animation, and theoretically, it could remain in that state indefinitely without any further deterioration in quality.
This principle has been validated by a growing body of clinical evidence. Human embryos that have been stored in liquid nitrogen for ten or more years have been thawed and used successfully in IVF treatment, resulting in healthy pregnancies and births. Some studies have reported successful outcomes from embryos stored for periods exceeding 20 years, which gives considerable confidence that long-term cryogenic storage does not inherently compromise sample quality when the vitrification process has been carried out correctly.
The caveats to this are practical rather than biological. The integrity of the storage system over time matters enormously. The liquid nitrogen level in the storage dewar must be maintained at all times, because any interruption to the cryogenic storage environment, even a partial warming of the tank, can cause irreversible damage to the samples within it. The quality of the vitrification kit used also matters. A high-quality closed system vit kit such as the CBS High Security Vitrification Kit provides better physical protection for the sample during long-term storage than an open carrier system, because there is no risk of the sample becoming dislodged from the carrier or contaminated during routine tank management.
Regulatory frameworks in the UK set specific limits on the duration for which certain types of samples, such as human embryos, can be stored, and these legal limits are separate from the biological question of how long samples can viably be kept. UK laboratories should always consult current HFEA guidance on permissible storage durations for licensed material.
Cryolab supplies CBS High Security Vitrification Kits alongside a full range of cryogenic storage equipment designed to support safe, long-term sample storage. Full details at cryolab.co.uk/product/vit-kit/
For more information visit: cryolab.co.uk/product/vit-kit/
Vitrification kits are manufactured from a combination of materials that are selected specifically for their thermal properties, their biocompatibility and their ability to withstand extreme cryogenic temperatures without cracking, degrading or leaching contaminants into the biological sample. Understanding what a vit kit is made from is relevant not only from a quality assurance perspective but also from a practical standpoint when it comes to handling and storage.
The carrier devices within a vitrification kit are typically made from medical-grade polymers or specialist materials such as polyimide, which can withstand rapid temperature changes without becoming brittle at cryogenic temperatures. The outer protective components of closed system carriers, such as those used in the CBS High Security Vitrification Kit, are designed to form a hermetic seal that protects the sample throughout the vitrification and storage process. The materials used must be certified as free from biological contaminants and must not interact chemically with the cryoprotectant solutions or the biological material itself.
The cryoprotectant solutions included in a vitrification kit are typically formulated from compounds such as dimethyl sulphoxide, ethylene glycol, sucrose and other penetrating and non-penetrating cryoprotective agents. These are prepared under controlled laboratory conditions and supplied in ready-to-use format in most commercial vit kit products, which reduces preparation time in the laboratory and minimises the risk of preparation errors.
On the question of reusability, the straightforward answer for most clinical applications is no. Vitrification carriers and the associated consumables in a vit kit are single-use items in clinical settings. This is not merely a commercial consideration but a genuine biosafety requirement. Reusing a carrier that has previously held biological material, even after cleaning, introduces an unacceptable risk of cross-contamination between samples. For any laboratory operating under regulatory oversight, single-use consumables are the expected standard.
The CBS High Security Vitrification Kit supplied by Cryolab is a single-use product, manufactured and packaged to clinical standards. Details on the product specification and ordering are available at cryolab.co.uk/product/vit-kit/
The success rates associated with vitrification kits have been consistently and substantially higher than those historically achieved with traditional slow-freezing methods, and this is one of the primary reasons that vitrification has become the dominant cryopreservation technique in reproductive medicine and an increasingly preferred method in research applications.
In the context of human oocyte cryopreservation, which represents perhaps the most clinically significant area where vitrification has transformed outcomes, survival rates with quality vitrification kits routinely exceed 85 to 95 percent in experienced clinical settings. Comparable survival rates with slow-freeze protocols for oocytes were historically much lower, often in the range of 50 to 70 percent, with considerable variability between laboratories. The improvement in oocyte survival rates attributable to vitrification has been so significant that the American Society for Reproductive Medicine removed the experimental label from egg freezing in 2012, partly on the basis of evidence demonstrating the reliability of vitrification outcomes.
For embryo cryopreservation, the picture is similarly favourable. Blastocyst survival rates following vitrification with a high-quality vit kit are consistently reported at above 90 percent in published clinical data from leading IVF programmes. Post-warming embryo quality is generally well-preserved, and clinical pregnancy rates from frozen embryo transfers using vitrified blastocysts are now in many programmes comparable to or in some cases exceeding those achieved with fresh embryo transfers.
It is important to note that the success rates achievable with any vitrification kit are not determined by the product alone. The skill and experience of the embryologist performing the procedure, the quality of the cryoprotectant solutions used, the speed and consistency of the process, and the integrity of the storage system all contribute to outcomes. However, starting with a high-quality, well-designed vit kit is a prerequisite for achieving the best possible results.
The CBS High Security Vitrification Kit from Cryolab is designed to give laboratories in the UK the platform they need to achieve consistently high survival rates while meeting the biosafety requirements of regulated clinical environments. The product is available at cryolab.co.uk/product/vit-kit/
For more information visit: cryolab.co.uk/product/vit-kit/
Choosing the right vitrification kit for your laboratory is a decision that should be made on the basis of several practical and regulatory factors, rather than on price alone. The right vit kit for one setting may not be the most appropriate choice for another, and it is worth taking the time to assess your laboratory’s specific requirements before committing to a product.
The first and most important consideration for any laboratory operating in a regulated clinical environment, such as an HFEA-licensed IVF clinic, is biosafety. Regulatory guidance in the UK and across Europe increasingly emphasises the use of closed system vitrification carriers that prevent direct contact between biological samples and liquid nitrogen. If your laboratory is subject to licensing or accreditation requirements, you should ensure that the vitrification kit you select meets those standards. The CBS High Security Vitrification Kit from Cryolab is a closed system product specifically designed for regulated clinical environments.
The second consideration is the type of samples you will be working with. Most quality vitrification kits are designed primarily for human embryos and oocytes, but if your laboratory works with other cell types, tissues or species, you should confirm that the product is appropriate for your application. Cryolab can advise on the suitability of the CBS range for different laboratory needs.
The third consideration is volume and workflow. A busy IVF unit processing a high number of samples will have different practical requirements from a small research laboratory vitrifying occasional samples. Consider how the vit kit integrates with your existing equipment and protocols, how quickly it can be used, and whether the supplier can provide consistent supply at the volumes you require.
The fourth consideration is technical support. Switching to a new vitrification kit or introducing vitrification for the first time in a laboratory requires confidence in the product and access to reliable technical guidance. A supplier that understands cryopreservation and can support your team through the process of adoption is worth considerably more than a marginal saving on the unit cost of the kit.
Cryolab supplies the CBS High Security Vitrification Kit to laboratories across the UK and is available to advise on the right product for your setting. Contact the team at info@cryolab.co.uk or visit cryolab.co.uk/product/vit-kit/ to learn more and place your order.
Dry shipper contains an absorbent lining that soaks up liquid nitrogen and releases it as vapour, meaning there is no free liquid inside. This makes dry shippers safe to transport by air under IATA regulations and suitable for moving biological samples internationally. A regular liquid nitrogen dewar holds free liquid and is designed for stationary storage rather than transport. The choice between the two depends entirely on whether your samples are moving or staying in place.
Related resource: Compare dry shippers and storage dewars at Cryolab.co.uk
No. Embryo storage requires a dewar specifically designed for biological sample inventory management with appropriate canister and cane configurations, consistent thermal performance, and compatibility with monitoring systems. Not all cryogenic dewars offer these features. Using a vessel not designed for long-term biological storage risks temperature inconsistencies and organisational errors that could compromise sample viability or traceability.
Related resource: See Cryolab’s embryo storage dewars
UK fertility clinics storing gametes and embryos must be licensed by the HFEA. The HFEA Code of Practice sets requirements for storage conditions, monitoring, record keeping, and equipment maintenance. COSHH regulations also apply to the handling of liquid nitrogen, requiring risk assessments, ventilation standards, and staff training. The HTA may be relevant if the clinic also works with human tissue in a broader research context.
Related resource: Cryolab supports HFEA and HTA compliance for UK clinics
Top-up frequency depends on the vessel’s static hold time, ambient conditions, and how often it is accessed. A high-performance storage dewar with minimal access may only need topping up every 60 to 100 days. A frequently accessed dewar in a busy lab environment may need topping up weekly. Monitoring systems that track liquid nitrogen levels continuously remove the guesswork and alert staff before levels become critical.
Related resource: Explore Cryolab’s liquid nitrogen monitoring systems
Post-thaw survival rates for sperm cryopreservation typically range from 50 to 80 percent of motile sperm, depending on the original sample quality, the cryoprotectant protocol used, the freezing method, and the quality of the storage environment. Samples from men with normal sperm parameters generally survive the freeze-thaw cycle better than those with pre-existing motility or morphology issues. Clinical outcomes in IVF with frozen sperm are comparable to fresh samples in most patient groups.
Related resource: Learn about Cryolab’s sperm cryopreservation equipment
For a small IVF clinic with moderate sample volumes, a 20L or 35L liquid nitrogen dewar typically offers the right balance of footprint, holding capacity, and manageable fill logistics. The specific internal configuration matters as much as the volume. A 20L dewar fitted with a canister-and-cane system for straw storage can hold thousands of individual samples. Clinics expecting growth should also consider scalability of their storage system rather than optimising only for current volume.
Related resource: See Cryolab’s 20L dewar range for IVF clinics
Yes. Frozen sperm shipped internationally must comply with IATA Packing Instruction 650, which governs UN 3373 Category B biological substances, while the dry shipper carrying it travels as not restricted under IATA Special Provision A152. The dry shipper used must be approved for air transport, free of free liquid, and accompanied by appropriate documentation. The receiving country may also impose additional import requirements. Clinics should work with specialist cryogenic logistics providers and ensure their dry shippers carry the appropriate certification.
Related resource: IATA-compliant dry shippers at Cryolab.co.uk
Cryogenic consumables such as cryovials, straws, and goblets should be stored in clean, dry conditions away from UV light and temperature extremes. Sterile consumables should remain in their original packaging until the point of use. For consumables that will come into contact with biological samples, ensuring sterility and traceability is essential. Batch numbers should be recorded against each use to support any downstream quality investigation.
Related resource: Browse Cryolab’s sterile cryogenic consumables range
If liquid nitrogen runs out in a storage dewar, embryos held in the liquid phase are immediately at risk of warming and viability loss. Embryos in the vapour phase have a slightly longer buffer time before reaching critical temperatures, but the window is narrow. This is why continuous monitoring systems with automated alarms and backup protocols are essential in any clinical storage environment. Recovery procedures and emergency nitrogen supply contracts form part of any compliant fertility clinic’s business continuity plan.
Related resource: Protect your samples with Cryolab monitoring and alarm systems
20L liquid nitrogen dewar is a popular and practical choice for veterinary fertility programmes managing bovine semen, equine embryos, or canine reproductive material. It offers manageable size for facilities with limited storage space while providing sufficient capacity for active programmes with moderate sample volumes. For larger commercial breeding operations, a 35L or larger vessel may be more efficient, reducing fill frequency and providing more headroom for inventory growth.
Related resource: Veterinary cryogenic storage solutions at Cryolab.co.uk
In common laboratory use the terms are often interchangeable, but there is a technical distinction. A dewar is a vacuum-insulated vessel designed primarily for storing and dispensing smaller volumes of liquid nitrogen – typically 2 to 50 litres – in a laboratory or clinical setting. A cryogenic tank or storage vessel is typically a larger, canister-based system designed for long-term biological sample storage rather than liquid dispensing. Both are available from Cryolab’s storage vessel range.
Hold time varies by model and charge quality. The CryoStork V3 provides sufficient hold time for UK domestic transport and same-day return journeys when correctly charged. The CryoStork V10 supports extended transport scenarios and higher-volume consignments. Hold time is directly affected by charging completeness – a partially charged shipper will not achieve the published hold time. Always charge to manufacturer specification and verify no free liquid remains before dispatching.
Liquid nitrogen boils at -195.8 degrees C at atmospheric pressure. For biological cryopreservation, the critical threshold is approximately -130 degrees C – the point below which biological samples enter a vitreous (glassy) state where biochemical activity effectively ceases. All IVF samples must be maintained below this threshold at all times. Vapour phase storage in a properly managed vessel maintains temperatures between -150 and -190 degrees C depending on fill level and vessel design
The Health and Care Act 2022, in force from 1 July 2022, extended the maximum permissible storage period for gametes and embryos from 10 years to 55 years for patients who provide relevant consent. Consent must be renewed every 10 years. This has significant implications for storage capacity planning – units must now provision for samples that may remain in storage for up to five decades. Speak to Cryolab about vessel options suited to long-term storage alongside clinical IVF applications.
The principal criteria are: ISO 9001:2015 certification, UK stock availability, technical support with relevant laboratory experience, and a product range covering the full workflow from freezing through storage and transport. Cryolab has supplied UK fertility labs and NHS trusts for over 40 years and holds ISO 9001:2015 certification. Contact the team directly or explore the full product range at cryolab.co.uk.
The honest answer is that no upper time limit for cryo preservation has been established by published clinical data. Embryos stored for over 20 years have resulted in successful pregnancies and healthy live births following frozen embryo transfer, and the theoretical basis for indefinite preservation below -130°C is sound because molecular movement effectively ceases in the glassy state. The limiting factor in practice is not biological degradation but equipment integrity over time and the regulatory framework governing consent.
In the UK, the Health and Care Act 2022 extended the maximum statutory storage period to 55 years, with consent renewed every 10 years. The practical challenge for IVF clinics is maintaining equipment reliability over decades-long storage periods. A storage vessel that was purchased when material was first frozen may have been replaced two or three times before that material is used. The audit trail linking the original sample to its current storage location across multiple vessel changes is a compliance requirement that becomes harder to maintain as time passes. This is why the quality of the sample organisation system inside the vessel, including cryocanes, visotubes, and cryosleeves, matters as much as the vessel itself. We supply storage vessels specified for long-term biological cryo preservation. Contact Cryolab to discuss storage infrastructure for your facility.
The price of liquid nitrogen in the UK varies because LN2 is produced as a byproduct of air separation, and the economics of production, compression, storage, and distribution create significant cost variation between suppliers depending on their plant locations, distribution networks, and contract structures. A laboratory 5 miles from a production facility may pay substantially less per litre than a comparable facility 80 miles away, even from the same supplier, because delivery cost is built into the price.
The most effective negotiating levers are volume commitment and delivery frequency. Suppliers price cylinder delivery at a premium over bulk tank delivery because the labour and vehicle cost of delivering 50-litre cylinders to multiple clients is high relative to the LN2 volume delivered. A laboratory that can commit to a minimum annual volume in exchange for a fixed price per litre, with a defined delivery schedule rather than ad hoc orders, will typically achieve a better rate than one ordering reactively. It is also worth asking specifically about the standing charge structure, because some supplier contracts include a minimum monthly charge that may apply even in months of low consumption.
The most effective way to reduce the total cost of LN2 is to reduce wastage through better vessel selection. We supply storage dewars with low static evaporation rates that reduce consumption regardless of what you pay per litre. Contact Cryolab for vessel specifications or ask CryoGPT to calculate the consumption impact of switching vessel models.
Yes, and this transfer step is one of the most underappreciated sources of embryo viability risk in the vitrification workflow. The period between loading the embryo onto the carrier and submerging it into liquid nitrogen in the storage vessel involves a brief exposure to ambient conditions that, if prolonged even by seconds, can initiate the ice crystal formation that vitrification is specifically designed to prevent. The risk is compounded if the storage vessel is not immediately accessible, if the canister and cane position inside the vessel has not been pre-identified before the vitrification process begins, or if there is any delay in locating the correct storage position during the transfer.
The practical controls are procedural as much as technical: the storage vessel should be opened, the target canister identified, and the cane position confirmed before vitrification begins, not after. The carrier should move from the loading environment to the LN2 surface in a single continuous motion. Closed high security carriers offer an additional protective advantage here because the sample is enclosed within the straw during submersion, preventing direct atmospheric exposure during the transfer arc. We supply CBS High Security vitrification kits and the cryocanes and canisters used to organise samples within storage vessels. Contact Cryolab for protocol support on vitrification transfer technique.
There is no fixed replacement interval for cryogenic tanks used in IVF laboratories because the operational lifespan of a well-maintained vessel depends on build quality, usage pattern, and storage environment. A high-quality dewar with a robust vacuum system, stored in a stable temperature environment and not subjected to physical impacts, can remain in reliable service for 10 to 15 years or longer. A lower-quality vessel, or one that has been dropped, knocked, or stored in a damp environment that accelerates outer wall corrosion, may fail within 3 to 5 years.
The replacement decision should be triggered by observable indicators rather than calendar age alone. The primary triggers are: frost or condensation on the outer wall indicating vacuum loss, LN2 consumption significantly above the rated static evaporation figure, visible deformation of the neck or body, a vacuum warranty that has expired with no replacement assessment carried out, and any incident involving physical impact to the vessel. Waiting for a complete failure event before replacing a cryogenic tank holding biological material is not an acceptable risk management approach. We supply replacement storage vessels across all capacities with a 3-year vacuum warranty, available for fast delivery across the UK. Contact Cryolab if you are assessing a vessel in your facility for replacement.
The minimum PPE requirement for any task involving direct handling of liquid cryogenic materials in a clinical laboratory is cryogenic gloves, a face shield or safety goggles rated for cryogenic splash, and a laboratory coat or apron that covers exposed skin on the arms and torso. Ordinary laboratory gloves, including nitrile and latex examination gloves, provide no meaningful protection against cryogenic contact and should never be used as the primary hand protection during LN2 handling tasks.
Cryogenic gloves must be loose-fitting rather than tight. This is counterintuitive but critical: if liquid nitrogen contacts the glove surface and is unable to drain away because the glove fits tightly against the skin, the insulating effect of the glove is rapidly overcome and a cryogenic burn occurs before the glove can be removed. A loose-fitting glove allows LN2 to drain away from the skin surface before heat transfer reaches a damaging level. For dispensing operations where larger volumes of liquid cryogenic material are handled, a cryogenic apron and ankle-protecting footwear should be added to the standard minimum. All PPE should be inspected before each use and replaced at the first sign of degradation. We supply cryogenic gloves, face shields, and aprons specified for laboratory liquid nitrogen handling tasks. Contact Cryolab for a full PPE specification for your facility.
Yes. The most serious indirect hazard of liquid nitrogen is asphyxiation from nitrogen gas accumulation in enclosed or poorly ventilated spaces, which kills without any direct contact between the liquid and a person’s body. A 20-litre dewar releasing its contents into a room of 50 cubic metres produces enough nitrogen gas to reduce oxygen concentration below the HSE’s 19.5 per cent threshold within minutes. Because nitrogen gas is colourless and odourless, there is no sensory warning. A person entering a room where nitrogen has accumulated may lose consciousness within seconds of crossing the threshold, with no opportunity to self-rescue.
The second indirect hazard is pressure-related. A closed container that has been accidentally sealed while containing liquid nitrogen or very cold nitrogen vapour, including improvised cold traps, blocked vent lines, and sealed centrifuge tubes cooled in LN2, can build pressure rapidly as the nitrogen warms and expands at its 694:1 vaporisation ratio. Vessel failure under this pressure can project fragments at high velocity across the laboratory. Neither of these hazards requires anyone to touch the liquid nitrogen directly. Fixed oxygen depletion monitors are the essential control for the asphyxiation risk. We supply cryogenic safety equipment including PPE for direct handling risks and can advise on the safety infrastructure required for compliant LN2 storage. Contact Cryolab for a laboratory safety equipment specification.
The fundamental cryopreservation processes used in human IVF and veterinary reproductive applications are similar in principle but diverge significantly in equipment specification, regulatory requirements, and consumable standards. Both sectors use liquid nitrogen for storage and controlled rate freezing or vitrification for the cryopreservation step. The differences emerge in the quality standards applied to consumables, the regulatory framework governing the stored material, and the physical scale of the operations.
Human IVF equipment must meet UKCA and CE marking requirements for medical devices, and IVF clinics are licensed and inspected by the HFEA. Consumables including straws, carriers, and cryoprotectant media must pass mouse embryo assay testing to confirm biological safety before use on human gametes. Veterinary applications operate under different regulatory frameworks and the MEA testing requirement does not apply in the same way. The scale difference is also significant: bovine semen is routinely processed in batches of thousands of straws simultaneously, requiring high-throughput controlled rate freezing equipment that would be unnecessarily large for a human IVF laboratory processing tens of embryos per cycle. We supply cryopreservation equipment and vitrification consumables for human IVF applications, with storage vessels suitable for both clinical and research use. Contact Cryolab to discuss equipment requirements for your specific application.
There is no single minimum room size prescribed in UK regulation for a cryogenic storage facility, but the ventilation requirement that flows from the volume of LN2 stored effectively sets a practical lower limit. The HSE’s guidance on working with cryogenic liquids requires that the ventilation arrangement for any room storing liquid nitrogen must be capable of preventing oxygen concentration from falling below 19.5 per cent in the event of a complete vessel failure releasing all stored LN2.
The calculation that determines whether a given room is adequate starts with the total LN2 volume stored at maximum capacity, converts this to the equivalent volume of gaseous nitrogen at room temperature (multiply litres of LN2 by 694), and then determines whether the room’s volume and ventilation rate can dilute this gas release sufficiently to prevent oxygen depletion below the threshold. A room storing 100 litres of LN2 across multiple vessels must be capable of safely managing 69,400 litres of nitrogen gas in a worst-case release scenario. For a 50 cubic metre room, this represents a complete atmosphere replacement requirement many times over, which in practice means either a very high-capacity mechanical ventilation system or a larger room. We supply cryogenic storage vessels for IVF cryogenic facilities of all sizes and can advise on the storage configuration that best fits your available space. Contact Cryolab for facility planning guidance.
Mechanical compressor systems reach practical lower limits of around -80°C to -100°C before the engineering challenges of achieving further temperature reduction become prohibitive. Below this range, the refrigerant gases used in mechanical systems approach their own boiling points and the compressor work required increases exponentially whilst cooling efficiency declines. Achieving -130°C or below with a mechanical system is possible but requires multi-stage cascade refrigeration with specialist refrigerants, the result being a complex, expensive, energy-intensive system with many potential failure points.
Liquid nitrogen cryogenic refrigeration reaches -195.8°C passively, with no moving parts, no electrical power requirement during normal operation, and no mechanical failure modes. The engineering challenge shifts from achieving the temperature to maintaining it efficiently over time, which is a vacuum insulation problem rather than a thermodynamic one. For biological storage applications in IVF where samples may remain in storage for years or decades, the reliability advantage of a passive LN2 system over a mechanical compressor system is significant. The absence of electrical dependency also means that a power cut does not immediately threaten stored biological material, provided LN2 levels are adequate. We supply storage dewars and dry shippers for passive cryogenic refrigeration in IVF and research applications. Contact Cryolab to discuss the right configuration for your laboratory.
Not always, but in the majority of cases a meaningful price difference between liquid nitrogen containers from reputable suppliers reflects genuine engineering differences rather than brand margin. The components of a liquid nitrogen container that drive legitimate price variation are the quality of the vacuum insulation system, the grade of stainless steel used for inner and outer vessel construction, the design and material of the neck plug and lid seal, and the quality assurance processes applied during manufacturing.
A container priced significantly below comparable vessels from established suppliers is most often cutting costs in one or more of these areas. The vacuum insulation is the most common point of compromise because its quality is invisible at the point of purchase and only becomes apparent over the first 2 to 3 years of use when the evaporation rate climbs above the rated specification. A vacuum that degrades within 2 years instead of lasting 5 to 10 years doubles or triples the effective cost of the vessel when LN2 consumption and early replacement are factored in. The 3-year vacuum warranty that Cryolab provides as standard on the storage vessel range is the clearest single indicator of vacuum build quality, because no manufacturer warrants a component it does not expect to last. Contact Cryolab for a specification and price comparison across the range or ask CryoGPT for guidance on which vessel suits your requirements.
Before cryogenic freezing equipment is used clinically in an IVF laboratory, a validation exercise should demonstrate that the equipment performs as specified and that the protocols used with it produce consistent results. For controlled rate freezers, validation typically includes temperature mapping of the cooling chamber to confirm that the probe reading reflects the actual temperature experienced by samples across the chamber volume, verification that the programmed cooling curve is achieved within the manufacturer’s tolerance at the rates specified in the clinic’s protocols, and a functional test of the LN2 solenoid valve and alarm systems.
For vitrification, which does not use a programmable freezer but relies on direct LN2 immersion, the validation focus shifts to the consumables and the technique rather than the equipment. Carrier performance should be validated by confirming that the warming protocol reliably recovers a test cell population above the threshold specified in the HFEA’s code of practice. Many UK IVF clinics use a mouse embryo assay on new consumable batches as part of their quality management system. HFEA expects to see validation records for cryogenic freezing equipment as part of the quality management documentation reviewed during inspection. We supply the CBS DigitCool controlled rate freezer and CBS High Security vitrification kits with technical documentation to support the validation process. Contact Cryolab for validation protocol guidance.
Vapour phase storage and liquid phase storage both use liquid nitrogen as the cooling medium, but samples are positioned at different heights within the vessel relative to the LN2 surface. In liquid phase storage, samples are submerged below the liquid nitrogen surface, where they are maintained at -195.8°C. In vapour phase storage, samples are held above the liquid surface in the nitrogen vapour that fills the vessel, where temperatures typically range from -140°C to -190°C depending on the height of the sample above the liquid and the vessel’s insulation characteristics.
The safety advantage of vapour phase storage is cross-contamination prevention. Liquid phase storage creates a theoretical risk that a microorganism or viral particle from a compromised sample straw could enter the liquid nitrogen and be carried to another sample during access events. Vapour phase storage eliminates this pathway because samples never share a liquid medium. The HFEA has highlighted this risk in its guidance and the majority of UK IVF clinics using vapour phase storage do so specifically to address it. The temperature in vapour phase is lower than the -130°C biological safety threshold in all properly functioning vessels, making it biologically equivalent to liquid phase for embryo viability. We supply storage vessels configured for both liquid phase and vapour phase storage, and cryocanes and visotubes compatible with vapour phase canister systems. Contact Cryolab to discuss the right configuration for your clinic’s protocol.
An open-neck biological storage dewar should never be under significant internal pressure during normal operation because the neck provides continuous venting of nitrogen vapour to atmosphere. If a storage vessel in an IVF laboratory shows signs of unexpected internal pressure, including a lid that is difficult to open, audible hissing from the neck area, or visible frost formation that does not correspond to normal evaporation patterns, the vessel should be treated as potentially unsafe and the surrounding area cleared of non-essential personnel immediately.
The most common cause of unexpected pressure in an open-neck storage vessel is ice formation in the neck that has partially or completely blocked the vapour vent path. This can occur when laboratory humidity is high and repeated lid openings allow moist air to enter and freeze inside the neck. In this scenario, the blockage should be cleared carefully with appropriate PPE and at a safe distance, never by inserting a probe that could dislodge a plug of ice explosively. The area should be well-ventilated before any intervention given the risk of localised nitrogen gas accumulation. Any vessel showing repeated evidence of neck icing should have its neck insulation and lid seal inspected. We supply storage vessels with neck and lid designs specified to minimise ice formation during normal laboratory use. Contact Cryolab immediately if you have a vessel showing unexpected pressure signs and require urgent guidance.
The most reliable indicators of a cryogenic supplier’s track record for an IVF clinic evaluating a first purchase are not the supplier’s own marketing claims but independently verifiable evidence of sustained supply to the regulated fertility sector. HFEA-licensed clinics operating in the UK are required to use equipment that meets defined standards, so a supplier’s established presence in the HFEA-regulated market is a meaningful signal. Asking a potential supplier for a reference list of HFEA-licensed clients it currently supplies, and verifying one or two of those references directly, takes 20 minutes and provides more reliable insight than any amount of marketing material.
Beyond references, the key assessments are: ISO 9001:2015 certification confirming the supplier’s quality management system is independently audited, UKCA and CE marking on the specific products being considered, the availability of material safety data sheets and technical documentation, and the supplier’s ability to confirm stock levels and delivery lead times for the products in question. A supplier that cannot readily produce any of these on request should not be approved for clinical supply. We have supplied cryogenic storage vessels, dry shippers, and IVF consumables to HFEA-licensed clinics and NHS fertility units for over 40 years. Contact Cryolab for supplier qualification documentation and references.
The maximum safe working pressure for a pressurised liquid nitrogen dewar varies by model but typically falls in the range of 1.7 to 2.5 bar gauge for supply and dispensing cylinders used in laboratory settings. Each vessel is fitted with a pressure relief valve calibrated to vent at a pressure below the vessel’s design burst pressure, providing a controlled release pathway that prevents catastrophic vessel failure. The relief valve is the last line of defence in the pressure management system, not the primary control.
If the relief valve itself fails to open when required, or if the vent path from the relief valve is blocked, pressure within the vessel can rise to the point of structural failure. At cryogenic temperatures the steel of the inner vessel becomes more brittle than at room temperature, which affects the failure mode under overpressure. A pressurised LN2 vessel that fails under overpressure does not simply split at the seam but can fail violently, projecting fragments and releasing a large volume of liquid nitrogen and cold gas simultaneously. This is why the relief valve on a pressurised liquid nitrogen dewar must be inspected at every service interval and the vent path confirmed clear of ice or particulate obstruction. We supply liquid nitrogen dispensing systems including pressurised supply vessels with calibrated pressure relief, and the cryogenic PPE required for safe operation. Contact Cryolab for technical documentation on pressure ratings for specific models.
A windowless room can be a safe location for a liquid nitrogen dewar provided the mechanical ventilation is adequate, but the absence of natural ventilation makes the engineering of the mechanical system more critical. The fundamental requirement is that the ventilation rate must be sufficient to prevent oxygen concentration from falling below 19.5 per cent in the event of a continuous LN2 release from the largest vessel in the room. A room with no windows and inadequate mechanical ventilation creates a confined space risk that is unacceptable under UK health and safety legislation for any location where liquid nitrogen is routinely stored.
The minimum acceptable ventilation for a windowless cryogenic storage room depends on the volume of LN2 stored, the room volume, and the rated ventilation air change rate. As a general principle, continuous mechanical ventilation providing a minimum of 10 air changes per hour is typically recommended for rooms storing more than a few litres of LN2, but this figure should be calculated specifically for the actual storage volume and room geometry rather than applied as a blanket standard. A fixed oxygen depletion monitor with an alarm that activates outside the room is also required, because a windowless room provides no visual indication to someone outside that conditions inside have changed. We supply cryogenic storage vessels and cryogenic safety equipment for facilities of all configurations. Contact Cryolab for storage room safety guidance specific to your facility layout.
The temperature threshold below which long-term biological viability is reliably maintained is -130°C. Above this point, the biological material transitions out of the fully glassy state and molecular mobility begins to return. At temperatures between -130°C and -80°C, ice recrystallisation can occur in vitrified samples over time, causing progressive cellular damage that may be cumulative rather than immediately apparent. A sample stored at -120°C for weeks or months may show no obvious signs of damage at the storage temperature but demonstrate significantly reduced viability at thaw compared with a sample maintained continuously below -130°C.
This is why nitrogen storage temperature is not simply a matter of keeping samples cold but of keeping them below a specific biological threshold. Dry shippers operating in vapour phase typically maintain temperatures between -150°C and -190°C, well below the -130°C boundary. Storage dewars in good vacuum condition maintain liquid phase temperature at -195.8°C. Problems arise during access events, transfers between vessels, and periods when LN2 levels have been allowed to fall below the sample level inside the vessel. Monitoring nitrogen storage temperature as an active quality control parameter rather than assuming all is well because the vessel contains LN2 is the standard that HFEA expects to find documented in clinic quality records. We supply storage vessels and dry shippers with temperature performance data for all models. Contact Cryolab to discuss temperature monitoring for your facility.
Working pressure is the maximum pressure at which a liquid nitrogen tank is designed to operate continuously in normal service. Test pressure is the higher pressure to which the vessel is hydrostatically tested during manufacture to confirm structural integrity before it leaves the factory. Test pressure is typically 1.5 times the working pressure, meaning a vessel with a 2.0 bar working pressure is tested to 3.0 bar during manufacture. The test pressure is not a safe operating pressure but a proof pressure that confirms the vessel has a safety margin above its intended working range.
When evaluating a liquid nitrogen tank for purchase, the relevant figure for operational planning is the working pressure, not the test pressure. A supplier quoting test pressure figures rather than working pressure figures is either poorly informed about their own products or presenting the more impressive number to avoid scrutiny of the actual operational specification. For open-neck biological storage dewars used in IVF laboratories, working pressure is atmospheric because the neck vents continuously. For pressurised supply and dispensing cylinders, the working pressure and the pressure relief valve setting are both important specifications that should be confirmed before purchase and checked against the intended application. We supply open-neck storage dewars and pressurised LN2 dispensing systems with full pressure specification documentation. Contact Cryolab for technical data on any vessel in the range.
A well-designed cryogenic system for biological storage in an IVF laboratory has no dependency on electrical power during normal operation. Liquid nitrogen storage dewars are passive vessels that maintain temperature through vacuum insulation alone, with no pumps, compressors, or electronic components required to keep samples cold. A power cut that lasts hours or even days does not directly threaten biological material stored in properly functioning LN2 vessels with adequate liquid nitrogen levels.
The components of a cryogenic system that do have electrical dependency and therefore require contingency planning are the oxygen depletion monitoring and alarm systems, the temperature and LN2 level alarm systems if installed, and any controlled rate freezer that is mid-programme at the time of the power cut. For oxygen and temperature alarms, battery backup or connection to a generator circuit ensures continuous monitoring. For a controlled rate freezer mid-programme, a power cut interrupts the LN2 solenoid valve operation and the cooling programme simultaneously, leaving the sample at whatever temperature it had reached. Most modern controlled rate freezers have internal battery backup sufficient to log the interruption and hold the last temperature for a short period, but a sample mid-programme during a power cut should be assessed before use. We supply passive LN2 storage vessels and dry shippers that require no electrical power to maintain cryogenic temperatures. Contact Cryolab for guidance on power resilience planning for your cryogenic system.
The most consistently reported source of error when a laboratory first introduces vitrification is timing. The two equilibration steps that precede loading onto the carrier involve exposing the embryo to increasing concentrations of cryoprotectant for defined time periods, typically 3 minutes in the first solution and 30 to 50 seconds in the second. The second equilibration step is the critical one. The high-concentration solution begins drawing water out of the cell rapidly, and if the embryo remains in it for longer than the specified time, osmotic damage occurs before the vitrification step. If it is removed too early, insufficient cryoprotectant has loaded and ice crystal formation occurs during cooling.
The second most common error is a delay between completing the carrier loading step and submerging the carrier into liquid nitrogen. The moment the embryo is on the carrier in the high-concentration solution, the clock for submersion is running. Any hesitation, including difficulty locating the correct storage position in the vessel, an interruption in the laboratory, or a stumble in the loading technique, extends the time in solution beyond what the protocol intends. Preparation before the vitrification step begins is not optional but essential: the storage vessel open, canister and cane position confirmed, and carrier submerged in LN2 ready to receive the loaded straw should all be in place before the embryo enters the first equilibration solution. We supply CBS High Security vitrification kits, storage vessels, and cryocanes and canisters for the complete vitrification workflow. Contact Cryolab for protocol support on first-time vitrification setup.
All liquid nitrogen storage vessels lose LN2 to evaporation continuously, even when the lid is firmly closed and no samples are being accessed. This happens because no insulation system is perfect. The vacuum layer between the inner and outer walls of a storage dewar slows heat ingress dramatically but cannot eliminate it entirely. Heat conducted through the neck of the vessel and radiated through the vacuum space causes a small but constant rate of surface boiling at the liquid nitrogen interface, producing nitrogen gas that vents through the neck.
The rated static evaporation figure on a dewar specification sheet quantifies exactly this loss. A vessel rated at 0.1 litres per day is losing that volume continuously regardless of whether the laboratory is open or closed. Over a bank holiday weekend, a vessel at that rate loses 0.3 litres. A vessel at 0.35 litres per day loses just over 1 litre across the same period. For IVF laboratories storing embryos across multiple vessels, understanding this baseline loss is essential for LN2 top-up scheduling and for identifying when a vessel’s evaporation rate has climbed above its rated specification, which typically indicates vacuum degradation.
We supply a storage dewar range specified with rated static evaporation figures for every model, and LN2 dispensing systems to make top-up operations safer and more controlled. Contact Cryolab to discuss vessel selection or ask CryoGPT for evaporation rate comparisons across the range.
Liquid nitrogen and dry ice are both used for low-temperature sample transport but they operate at fundamentally different temperatures and suit entirely different applications. Dry ice is solid carbon dioxide that sublimes at -78.5°C. Liquid nitrogen boils at -195.8°C. The 117°C gap between them is not a detail but a clinical distinction that determines whether vitrified biological material survives transport intact.
Dry ice is appropriate for transporting reagents, culture media, and samples that require only short-term cold storage above -80°C. It is entirely unsuitable for transporting vitrified embryos, oocytes, or sperm because the temperature it maintains is more than 100°C above the -130°C glassy state threshold below which recrystallisation cannot occur. A vitrified embryo transported on dry ice will almost certainly suffer irreversible cellular damage before it arrives. Liquid nitrogen in a vapour phase dry shipper maintains temperatures well below -130°C for 7 to 14 days in any orientation, making it the only appropriate medium for inter-facility transfer of cryopreserved reproductive material.
We supply the CryoStork dry shipper range for IVF specimen transport and vitrification consumables for the loading and preparation stage. Contact Cryolab to specify the right transport solution for your clinic’s requirements.
Technically yes, but in practice the manual transfer of liquid nitrogen between vessels without specialist dispensing equipment is one of the highest-risk routine tasks in an IVF laboratory. Flash vaporisation of LN2 on contact with a warmer vessel surface produces rapid localised nitrogen gas release that can cause LN2 to spit and splash unpredictably. A ladle or flexible hose transfer into a cold dewar that has not been pre-cooled can result in vigorous boiling that propels LN2 upward rather than into the vessel.
Beyond the immediate safety risk, uncontrolled manual transfer loses a significant proportion of the LN2 to vaporisation before it reaches the destination vessel. Losses of 10 to 20 per cent per transfer are common with ladle methods, which compounds into a meaningful annual cost across multiple vessels and daily top-up cycles. A controlled pressurised dispensing system eliminates the unpredictable splash phase, delivers LN2 at a controlled flow rate, and allows the operator to maintain a safe working distance during the fill.
We supply the CryoCrest LN2 dispensing range for safe controlled transfer between vessels of all sizes, alongside the cryogenic PPE required for any LN2 handling task. Contact Cryolab to specify the right dispensing solution for your laboratory.
Yes, and the service interval matters more than most laboratory managers realise until a controlled rate freezer fails mid-programme. The LN2 solenoid valve that controls nitrogen injection into the cooling chamber is the component most susceptible to wear and failure. A solenoid that sticks open or fails to open on command produces a cooling curve that deviates from the programmed profile without triggering an obvious alarm in all models, producing biological material that appears correctly processed but has in fact experienced uncontrolled temperature deviation during the critical nucleation phase.
Most manufacturers recommend annual servicing for controlled rate freezers under regular use, with more frequent checks on the solenoid valve, the temperature probe calibration, and the LN2 supply connection integrity. Laboratories running multiple freeze programmes per week should consider 6-monthly probe calibration checks as a minimum. The programme log stored by modern controlled rate freezers is a valuable quality record and should be archived for every run as part of the clinic’s HFEA quality management documentation.
We supply the CBS DigitCool controlled rate freezer for IVF and biobanking applications. Contact Cryolab for servicing guidance or to discuss a replacement programme for an ageing unit in your facility.
The earliest and most reliable indicator of vacuum failure in a cryogenic storage tank is frost or condensation forming on the outer wall of the vessel. Under normal operating conditions, the vacuum insulation between the inner and outer walls prevents the outer surface from cooling to the dew point of the surrounding air. When the vacuum degrades, the outer wall begins to conduct cold from the inner vessel, causing moisture in the laboratory air to condense or freeze on the outer surface as a band of frost or persistent condensation that does not clear when the vessel is moved to a warmer environment.
A secondary indicator is a sudden increase in LN2 consumption. If a vessel that previously required weekly top-up now needs topping up every 3 to 4 days with no change in access frequency, the vacuum is likely compromised. Once vacuum failure is confirmed, the vessel should be treated as approaching end of life. Biological material should be transferred to a replacement vessel as soon as possible rather than waiting for a complete failure event.
We supply replacement storage dewars across a range of capacities with a 3-year vacuum warranty as standard. Contact Cryolab if you suspect vacuum failure in a vessel currently holding biological material so we can advise on the fastest replacement route.
NHS fertility units applying their own supplier approval processes typically require a minimum set of documented qualifications before a cryogenic equipment supplier can be added to the approved vendor list. ISO 9001:2015 quality management system certification is the baseline requirement and covers the supplier’s manufacturing, procurement, and quality control processes. UKCA marking on individual products confirms that the equipment meets UK conformity requirements post-2021. CE marking remains valid in parallel and is required for any products supplied to European fertility clinics.
Beyond the certification baseline, NHS procurement teams typically require evidence of supply to other NHS or regulated healthcare facilities, access to safety data sheets and technical documentation for all products, a documented complaints and non-conformance handling process, and in some cases a site visit or quality audit. A supplier without its own ISO 9001:2015 certified quality management system cannot demonstrate the same level of documented process control as a specialist supplier with direct manufacturing relationships.
We hold ISO 9001:2015 certification and supply UKCA and CE marked cryogenic storage vessels, dry shippers, and vitrification consumables to NHS fertility units, private IVF clinics, and research institutions across the UK. Contact Cryolab for supplier qualification documentation to support your vendor approval process.
The time between an LN2 supply tank running empty and biological material reaching the critical -130°C threshold depends entirely on the static evaporation rate of the storage vessel holding the samples and how much LN2 remained in the vessel at the point the supply ran out. A storage dewar with a 20-litre capacity, a static evaporation rate of 0.1 litres per day, and a current fill level of 10 litres has approximately 100 days of passive holding time before the vessel runs completely dry, assuming no access events. A vessel at the same fill level but with a degraded vacuum and an effective evaporation rate of 0.5 litres per day has 20 days.
The immediate risk is not the supply tank running empty but the cascade of events that follows if the situation is not identified and resolved quickly. A vessel that continues to lose LN2 without replenishment will eventually drop below the level at which samples are submerged in liquid phase. Once vapour phase temperature rises above -130°C, vitrified material begins to transition out of the glassy state. This is why monitoring LN2 levels across all storage vessels, not just the supply tank, is an essential daily task.
We supply storage dewars with low evaporation rates that extend the passive holding window in a supply disruption, and LN2 dispensing systems that make emergency cross-filling faster and safer. Contact Cryolab or ask CryoGPT for guidance on LN2 supply contingency planning.
HFEA does not prescribe a specific job title for cryogenic equipment maintenance responsibility, but the licensed centre’s Person Responsible is ultimately accountable for ensuring that all equipment used in the storage of gametes and embryos is maintained in a condition fit for purpose. In practice, this responsibility is typically delegated to a senior embryologist or laboratory manager who is named in the quality management system as the equipment maintenance lead.
What HFEA expects to find during an inspection is a documented maintenance schedule for each piece of cryogenic equipment, records of maintenance activities actually carried out against that schedule, a process for identifying and escalating equipment that is no longer performing to specification, and evidence that staff carrying out maintenance tasks have received appropriate training. The maintenance schedule should cover LN2 level monitoring frequency, vessel evaporation rate checks, oxygen depletion monitor calibration intervals, dry shipper pre-charge verification, and PPE inspection and replacement criteria.
We supply storage vessels, dry shippers, and cryogenic safety equipment with full technical documentation suitable for inclusion in an HFEA maintenance register. Contact Cryolab for a maintenance schedule template or ask CryoGPT for an immediate HFEA equipment compliance checklist.
Emergency delivery lead times from UK liquid nitrogen suppliers vary significantly depending on the supplier, contract terms, geographic location, and the time of day the request is made. The majority of UK industrial gas suppliers offer next-day emergency delivery as a contracted option, but same-day delivery is rarely guaranteed outside major urban areas and typically attracts a significant premium charge. For laboratories in rural locations or those served by regional depots with limited delivery capacity, even next-day emergency delivery cannot always be relied upon.
The emergency delivery lead time from your specific supplier should be a known and documented figure, not something you find out for the first time when you actually need it. The contingency trigger point should be set conservatively enough that the total passive holding time across all storage vessels exceeds the worst-case emergency delivery lead time by a comfortable margin. For most IVF laboratories, a trigger point equivalent to 48 to 72 hours of passive consumption at normal rates is a reasonable minimum.
We can advise on the storage vessel specifications that maximise passive holding time in a supply disruption. Contact Cryolab to discuss LN2 supply resilience for your facility or ask CryoGPT for immediate guidance on contingency planning.
Switching from cylinder LN2 supply to bulk liquid nitrogen delivery requires on-site infrastructure that most fertility clinics do not have in place at the point they first consider the transition. The primary requirement is a bulk storage tank, typically a vacuum-insulated vessel of 500 litres or more installed externally or in a dedicated plant room, connected to the laboratory’s internal distribution pipework via insulated transfer lines. The tank must be sited on a concrete pad capable of supporting its loaded weight, with adequate clearance from building openings, ventilation inlets, and ignition sources as specified by the gas supplier’s site survey requirements.
The site survey carried out by the bulk LN2 supplier before installation is not optional. It assesses access for the delivery tanker, proximity to overhead power lines and drainage systems, ground conditions, and ventilation around the tank location. Planning permission is not typically required for a cryogenic storage tank below certain size thresholds in the UK, but listed buildings and conservation area sites may require prior approval. Total infrastructure cost including tank, pipework, and installation typically ranges from £3,000 to £8,000 depending on site complexity.
We supply LN2 dispensing systems that integrate with both cylinder and bulk supply arrangements, and storage dewars specified for the end-use biological storage stage of the supply chain. Contact Cryolab to discuss how your facility’s LN2 infrastructure should be configured.
There is no single piece of UK legislation that specifies exactly which oxygen monitoring equipment must be installed in a cryogenic laboratory. The legal framework is the Health and Safety at Work Act 1974 and the associated Management of Health and Safety at Work Regulations 1999, which require employers to identify and control significant risks. The HSE’s guidance on working with cryogenic liquids makes clear that a fixed oxygen depletion monitoring system with an audible alarm is expected in any room where liquid nitrogen is stored in quantities capable of reducing oxygen concentration below 19.5 per cent.
A cryogenic laboratory cannot rely on portable oxygen monitors that may be left in a different room, discharged, or switched off. A fixed system with a sensor positioned at breathing height, connected to an audible alarm that activates outside the monitored room as well as within it, is the minimum standard that HFEA and HSE inspectors expect to find. The alarm threshold should be set at 19.5 per cent oxygen concentration as specified by the HSE, because cognitive impairment can begin before the concentration drops significantly below this threshold.
We supply cryogenic safety equipment for IVF and research laboratories and can advise on the full safety infrastructure required for a compliant cryogenic lab. Contact Cryolab for a safety equipment specification for your facility or ask CryoGPT for immediate HSE compliance guidance.
Multi-site expansion is one of the most common scenarios where a cryogenic storage approach that worked well for a single clinic begins to create operational and compliance problems. The issues that typically emerge are not about the equipment itself but about consistency, traceability, and the logistics of moving biological material between locations. A clinic that has used a single dewar model at site A may find that site B has different vessels from a different supplier, creating a maintenance and documentation landscape that is harder to manage and harder to defend during an HFEA inspection covering multiple licensed premises.
The most effective approach is to standardise the vessel fleet across all locations at the point of expansion rather than inheriting whatever equipment each site previously used. This means specifying a single storage vessel model, a single dry shipper model for inter-site transfers, and a single consumables range across all sites, so that staff training, maintenance schedules, and documentation templates are identical everywhere. It also means establishing a clear chain of custody protocol for every sample transfer between sites, with pre-charge verification records for each dry shipper journey and temperature log review at the receiving site before samples are transferred into permanent storage.
We supply storage vessels, dry shippers, vitrification consumables, and cryogenic accessories to IVF clinic groups standardising their equipment fleet across multiple sites. Contact Cryolab to discuss a multi-site equipment specification.
A cryogenic storage vessel that has passed its vacuum warranty but continues to maintain temperature is operating in a zone of increasing uncertainty rather than confirmed reliability. The vacuum warranty exists because the manufacturer can guarantee vacuum integrity up to that point, based on materials testing and accelerated life cycle data. Beyond the warranty period, vacuum integrity depends on factors that cannot be assessed without specialist equipment, including the condition of the molecular sieve material inside the vacuum jacket and the integrity of the getter compounds used to maintain vacuum quality over time.
A vessel that appears to be functioning may have a partially degraded vacuum that is still sufficient to maintain temperature under current conditions but will fail prematurely if subjected to physical shock, unusual ambient temperature, or simply continued use. If a storage incident occurs and it emerges that the vessel involved had an expired vacuum warranty and no documented replacement plan, the consequences for the clinic’s HFEA licence and patient relationships are significant.
The practical approach is to treat the vacuum warranty expiry date as the trigger for a vessel replacement assessment rather than automatic replacement. A vessel showing no signs of degradation may warrant a further period of monitored use. A vessel showing any degradation indicators should be replaced without delay. We supply replacement storage dewars and dry shippers across all capacities with fast UK delivery. Contact Cryolab to discuss a planned replacement programme for your facility’s ageing cryo equipment.
The short answer is no, and waiting for price reductions in the cryogenic storage vessel market is unlikely to be a sound procurement strategy for an IVF laboratory. The cryogenic tanks market has grown steadily but the specialist biological storage segment that serves IVF clinics has not followed the same price trajectory as commodity industrial cryogenic products. The engineering requirements for biological storage vessels including low static evaporation rates, vapour phase canister configurations, UKCA and CE marking, and ISO 9001 certified manufacturing, impose cost floors that commodity market growth does not erode.
Where price competition has increased in the market it has tended to produce lower-cost vessels with compromised vacuum quality rather than equivalent vessels at lower price points. The practical consequence for a laboratory that buys on price is typically a vessel with a faster-than-rated evaporation rate within 2 to 3 years and a shortened service life, which means the apparent saving at purchase is absorbed by higher LN2 costs and earlier replacement. A laboratory with a current storage need should procure based on total cost of ownership over five years rather than purchase price alone. We supply cryogenic storage vessels for IVF applications with rated evaporation figures and a 3-year vacuum warranty. Contact Cryolab for a total cost of ownership comparison across the range.
Yes. Since January 2022, products placed on the UK market must carry UKCA marking to demonstrate conformity with UK product safety requirements. A European supplier selling cryogenic equipment that carries CE marking but not UKCA marking is supplying a product that does not formally meet UK market conformity requirements, even if the underlying product standard is identical. For HFEA-licensed IVF facilities, the ability to demonstrate that all equipment meets applicable UK conformity requirements is a quality management expectation rather than an optional consideration.
In practice, many reputable European cryogenic equipment manufacturers applied for and obtained UKCA marking alongside their CE marking during the transitional period, and their products carry both marks. The issue arises with smaller European suppliers who have not obtained UKCA marking for the UK market and are selling CE-only products. Before purchasing from any European cryogenic supplier, UK laboratories should confirm that the specific product being purchased carries current UKCA marking and request a copy of the UK Declaration of Conformity. Cryolab supplies UKCA and CE marked cryogenic storage vessels and dry shippers with full conformity documentation. Contact Cryolab for compliance documentation for any product in the range.
Vitrification technology is mature in the sense that the underlying physical chemistry is well understood, the consumable systems are validated, and clinical outcomes data from millions of cycles confirms its reliability when performed correctly. It is not mature in the sense of being tolerant of operator variability or procedural shortcuts. The technique remains acutely sensitive to timing, temperature, and cryoprotectant concentration at every stage of the loading sequence, and operator-to-operator variability in survival rates within the same clinic is a documented quality management challenge even in high-volume centres with experienced teams.
The most reliable indicator of whether a laboratory’s vitrification process is under control is not the equipment or consumable brand but the consistency of survival rates across all operators and all sessions. A clinic where one embryologist achieves 95 per cent vitrification survival and another achieves 75 per cent using identical equipment and consumables has a technique variability problem that better equipment will not resolve. The closed high security carrier systems supplied by Cryolab reduce one source of variability by controlling the cooling environment, but the loading technique and timing discipline remain operator-dependent. We supply the CBS High Security vitrification kit range and storage vessels for post-vitrification biological storage. Contact Cryolab for protocol support and consumable recommendations.
The upgradability of cryogenic tech in an IVF laboratory depends entirely on which component is underperforming and what the cause of the underperformance is. Storage vessels with degraded vacuum cannot be economically repaired in the field because restoring a vacuum requires factory-level equipment and the economic cost typically exceeds the replacement value of the vessel. A dewar with confirmed vacuum loss should be replaced, not upgraded.
Equipment that can be legitimately upgraded rather than replaced includes controlled rate freezers, where a software update or solenoid valve replacement can restore performance to specification without replacing the unit, and sample organisation systems within existing dewars, where replacing canisters, cryocanes, or visotubes with a better-specified alternative can improve sample density and retrieval efficiency without replacing the vessel itself. The decision rule is whether the core function of the equipment remains capable of being restored to rated specification. If not, replacement is the only appropriate action. We supply replacement storage vessels, upgraded canister and cane systems, and replacement safety equipment for IVF laboratories upgrading their cryogenic tech. Contact Cryolab to discuss upgrade versus replacement options for your facility.
The 30 days before an HFEA inspection is not the time to create maintenance records that do not exist but it is the right time to review, consolidate, and address any gaps in existing records before the inspection team arrives. The cryogenic service and maintenance documentation that HFEA inspectors most commonly request covers four areas: purchase and installation records for each vessel including the model, serial number, purchase date, and vacuum warranty expiry; maintenance logs showing the frequency and outcome of LN2 level checks, evaporation rate monitoring, and outer wall inspections; calibration records for oxygen depletion monitors and temperature probes; and service records for any controlled rate freezers including the programme logs for recent freeze cycles.
The most common gap inspectors find is not in vessel purchase records but in the continuity of maintenance logs. A clinic that has been diligent about daily LN2 level checks but has recorded them on paper logs that were discarded after six months cannot demonstrate compliance over the required period. Maintenance records should be retained for the duration of the associated equipment’s operational life plus a defined period after disposal. Cryolab provides purchase documentation, warranty certificates, and technical data sheets with every item in the storage vessel range and the dry shipper range that are suitable for inclusion in HFEA quality management files. Contact Cryolab for replacement documentation or ask CryoGPT for an HFEA inspection preparation checklist.
The practical difference between a specialist cryo storage supplier and a general scientific distributor becomes apparent not at the point of purchase but at the point of a problem. A general scientific distributor can sell a cryogenic storage vessel, process the order, and deliver the product. What it typically cannot do is advise on which specific vessel configuration is appropriate for vapour phase biological storage in an HFEA-licensed facility, provide the compliance documentation required for a vendor approval process, or give technical guidance on LN2 level management, evaporation rate monitoring, or vessel maintenance.
A specialist cryo storage supplier for the IVF sector understands that the vessel is not the end point but the infrastructure around which a clinical storage programme is built. The question is not just which dewar to buy but how many canisters at what configuration, which cryocane and sleeve system is compatible with the vitrification consumables in use, how to calculate the LN2 supply requirement based on the vessel configuration and access frequency, and what documentation is required for HFEA compliance. We have operated exclusively as a cryo storage specialist for the biological and clinical sector for over 40 years, supplying storage vessels, sample organisation systems, and vitrification consumables. Contact Cryolab to discuss your facility’s cryo storage requirements.
There is no single nationally prescribed training qualification for liquid nitrogen tank handling in a UK IVF laboratory, but the Health and Safety at Work Act 1974 and the Management of Health and Safety at Work Regulations 1999 require employers to ensure that staff are competent to carry out the tasks they are assigned. For liquid nitrogen handling, competence encompasses knowledge of the hazards involved, practical skill in the specific tasks required, and familiarity with the emergency procedures for the facility.
As a minimum, staff authorised to handle liquid nitrogen tanks should have received training covering the three primary hazards of LN2 (cryogenic contact injury, asphyxiation from nitrogen gas accumulation, and pressure risk from sealed containers), the correct selection and use of cryogenic PPE, the procedure for LN2 top-up using the dispensing system in use at the facility, the pre-use safety checks required before handling any liquid nitrogen tank, the location and operation of the oxygen depletion alarm and emergency ventilation controls, and the first aid response to cryogenic contact injury. This training should be documented, signed off by a competent supervisor, and repeated at intervals defined in the facility’s quality management system. Contact Cryolab for guidance or ask CryoGPT for an LN2 handling competency checklist.
A dewar showing frost on its outer wall should not be used as a primary biological storage vessel while a replacement is sourced. Outer wall frost confirms that vacuum integrity has been lost to a degree sufficient to allow the outer shell to cool below the dew point of the ambient air, which means the insulation is failing and LN2 consumption will be significantly above the rated evaporation figure. The rate of further degradation is unpredictable once frost is visible, because the mechanism of vacuum loss tends to accelerate rather than stabilise.
The safe course of action is to immediately transfer biological material from the affected vessel into a vessel with confirmed vacuum integrity, which may require temporary consolidation of samples into remaining vessels if a replacement is not immediately available. Before consolidating, confirm that the receiving vessels have adequate capacity and that the transfer can be completed without exposing samples to temperatures above -130°C for more than a brief period. The affected dewar should remain in service as a secondary LN2 reservoir only, not as a biological storage vessel, until it is replaced. Cryolab maintains stock of replacement storage dewars across a range of capacities for urgent supply situations. Contact Cryolab immediately if you have a vessel showing outer wall frost and biological material that requires urgent transfer.
LN2 prices in the UK are linked to energy costs through the air separation process that produces liquid nitrogen, and to distribution costs through the vehicle and fuel costs of cylinder and bulk delivery. When the cryogenic gas industries experience supply disruptions, whether from plant maintenance shutdowns, energy price spikes, or logistics constraints, the effect on IVF laboratories is felt through price increases, extended delivery lead times, and in some cases temporary supply rationing.
The most effective protections against supply disruption impact are structural rather than reactive. A storage vessel fleet with low static evaporation rates provides a longer passive holding window that buys time to respond to a delivery delay. An on-site LN2 inventory maintained at a level that covers at least two full delivery intervals provides a buffer against schedule disruption. A pre-approved second-source supplier who has been contacted and qualified before an emergency provides an alternative supply pathway that can be activated quickly. We supply storage vessels with the low evaporation rates that maximise supply disruption resilience, and LN2 dispensing systems that minimise wastage when supply is constrained. Contact Cryolab to discuss supply resilience planning for your facility.
When an IVF laboratory faces multiple equipment replacement needs against a constrained capital budget, the prioritisation framework should be based on clinical risk rather than cost, age, or convenience. The equipment whose failure would most directly and immediately threaten stored biological material should be replaced first, regardless of its position in any planned replacement schedule.
Using this framework, a storage vessel showing vacuum degradation signs takes priority over a controlled rate freezer that is still performing within specification but approaching its recommended service life. An oxygen depletion monitor with an expired calibration certificate takes priority over replacing a dispensing system that works but is inefficient. The replacement decision should be documented with the clinical risk rationale clearly stated, so that the prioritisation can be demonstrated to be clinically driven if an HFEA inspector reviews the equipment replacement log during an inspection. A laboratory that has deferred replacing a vessel with confirmed vacuum degradation in favour of purchasing newer ancillary equipment will face difficult questions about clinical risk management if that vessel subsequently fails. We supply replacement IVF lab storage vessels, dry shippers, and safety equipment for laboratories working through planned replacement programmes. Contact Cryolab to discuss prioritisation for your facility’s equipment renewal needs.
Liquid nitrogen keeps embryos viable through one mechanism: stopping time. At -195.8 degrees C, every biological process that would cause cellular degradation comes to a complete halt. Metabolism stops. Enzymatic activity ceases. DNA damage pathways cannot operate. The embryo enters a state of suspended animation that has no known biological time limit, provided the temperature holds.
The science sits in what researchers call the glassy state. Water inside a cell, if cooled slowly, forms ice crystals that puncture membranes and destroy the cellular architecture that makes an embryo viable. Vitrification prevents this by cooling at rates exceeding 10,000 degrees C per minute (ASRM guidance). At that speed, intracellular fluid transitions directly from liquid to a glass-like amorphous solid. No ice crystals. No structural damage. No biological activity of any kind.
An embryo stored correctly at -195.8 degrees C for ten years is biologically identical to the same embryo at the moment it was frozen. There is no accumulation of time inside a properly maintained cryogenic vessel.
The clinical record supports this. Successful pregnancies have been reported from embryos stored for over 27 years in liquid nitrogen. The limiting factor on storage duration is not biology – it is the reliability of the cold chain and the quality of the storage infrastructure maintaining it. The CryoNest storage vessels used across UK IVF laboratories are designed to maintain performance at -195.8 degrees C with hold times that provide a genuine safety margin against supply interruptions. For storage infrastructure advice, contact Cryolab or use CryoGPT.
For embryos, the debate between slow freezing and vitrification was settled over a decade ago – vitrification produces consistently better survival rates and is now standard in UK IVF laboratories. For sperm, the picture is more complicated, and the answer matters for how UK andrology laboratories specify their equipment.
Slow freezing for sperm uses a controlled rate freezer to cool the sample progressively – typically at one to three degrees C per minute through the critical temperature zone. A glycerol-based cryoprotectant is added before freezing to draw water out of sperm cells and reduce ice crystal formation. Post-thaw motility recovery typically falls in the range of 30 to 50 percent of pre-freeze motility, which is considered acceptable for clinical use and has decades of validated outcome data behind it.
Vitrification for sperm applies the same ultra-rapid cooling approach used for embryos – direct plunging into liquid nitrogen after loading onto a carrier device. Published evidence shows vitrification can produce post-thaw motility comparable to or better than slow freezing in good-quality samples.
The practical barrier to sperm vitrification in UK andrology laboratories is not the science. It is the absence of widely validated clinical protocols for routine use and the unfamiliarity of most UK andrology teams with the technique at scale.
Slow freezing for sperm remains the most widely used and clinically validated approach in UK practice. For equipment across both approaches, Cryolab supplies the CBS DigitCool controlled rate freezer range and the full range of liquid nitrogen storage vessels. Contact us for protocol-specific equipment advice.
A liquid nitrogen storage vessel that has lost vacuum is one of the most serious equipment failures an IVF laboratory can experience – and it rarely announces itself clearly. The vessel continues to look normal from the outside. The liquid nitrogen level reads at an acceptable level for a period. But the thermal performance has already collapsed, and the samples inside are on a countdown.
The vacuum between the inner and outer walls of a dewar provides the insulation that keeps liquid nitrogen cold. Without it, the vessel becomes a double-walled container with no meaningful insulating capacity. The first sign of vacuum loss is almost always accelerated liquid nitrogen consumption. A vessel that normally holds its charge for 100 days may suddenly require topping up every week, then every few days.
By the time frost forms on the outside of a liquid nitrogen storage vessel, the vacuum has already failed. Frost on the outer wall is a late-stage symptom, not an early warning. The early warning is increased liquid nitrogen consumption in a single vessel.
The correct response to suspected vacuum failure is to transfer samples to a backup vessel immediately while investigation continues – not to wait and see. This is why backup storage is not optional in a licensed UK IVF setting. A charged backup storage vessel kept ready at all times is the single most important infrastructure decision supporting effective response to vessel failure. Contact Cryolab for advice on vessel inspection protocols and emergency transfer procedures.
International embryo transport is a regulated clinical procedure in the UK, not simply a logistics exercise. Before a single embryo leaves a licensed fertility clinic for another country, a specific set of legal, consent and documentation requirements must be met.
The legal framework starts with the HFEA. Any UK-licensed clinic proposing to export embryos must comply with HFEA requirements for the movement of gametes and embryos – confirming valid consent exists for export, that the receiving facility in the destination country meets acceptable regulatory standards, and that the movement is fully documented for traceability. The Human Fertilisation and Embryology Act 1990 (as amended) governs embryos created in the UK.
On the physical transport side, embryos must travel in a dry shipper – a liquid nitrogen transport vessel containing no free liquid nitrogen, classified as non-hazardous under IATA Packing Instruction 650. The CryoStork range is designed with IATA compliance in mind and is suitable for international air freight of biological samples.
The dry shipper gets most of the attention in an international embryo transfer. The consent, documentation and regulatory compliance requirements are where UK clinics most often find unexpected complexity.
For long-haul international transfers, the CryoStork V10 provides the capacity and extended hold time that gives a meaningful safety margin on complex itineraries. For regulatory guidance, the HFEA website is the authoritative reference. For dry shipper specification, contact the Cryolab team.
Sample traceability in a UK IVF laboratory is built into every physical component of the storage system – the straw colour, the visotube configuration, the goblet assignment, the canister labelling, and the vessel inventory records. HFEA requires that every sample in storage can be positively identified at any point during its storage period, which under the Health and Care Act 2022 can now extend to 55 years.
The physical identification layer starts with the straw. CBS High Security Straws are available in multiple colours and carry patient identification information sealed within the straw itself. Straws sit inside visotubes, which provide a colour-coded grouping layer by patient or sample batch. Visotubes sit within goblets, which sit within canisters assigned to specific positions within a named storage vessel.
Traceability in cryogenic storage is not about having a record somewhere. It is about being able to walk into the storage room, identify a specific vessel, open a specific canister, retrieve a specific goblet, and confirm the identity of the sample inside it – correctly, every time, under time pressure.
The cryogenic markers used at every labelling step must be rated for cryogenic temperatures. Standard permanent markers fail in liquid nitrogen – the ink cracks or detaches under thermal cycling, creating a HFEA inspection finding. For consumable selection to support a robust traceability system, contact Cryolab or use CryoGPT.
Biobanking and IVF cryogenic storage share the same fundamental technology – liquid nitrogen at -195.8 degrees C, the glassy state, and the same categories of storage vessel and consumable. What separates them is the regulatory framework, the purpose of storage, and the scale at which samples are managed.
An IVF laboratory stores embryos, oocytes and gametes for a specific patient’s treatment. The samples have a defined clinical purpose, a named patient, documented consent, and a regulatory home in the HFEA’s licensing framework – now with storage up to 55 years under the Health and Care Act 2022. A biobank stores biological material – blood, tissue, DNA, cell lines, stem cells – for use in research, diagnostics or drug development that may not be fully defined at the point of collection. Non-reproductive biobanking sits under the Human Tissue Authority and the Human Tissue Act 2004.
The practical difference between a biobank and an IVF cryogenic store is not the equipment. It is the governance. A biobank operates under a quality management framework – typically ISO 20387 – that governs how samples are collected, processed, documented, stored and accessed over potentially very long timeframes.
From an equipment perspective, the CryoNest storage vessel range suits both IVF clinical storage and biobanking applications. The CryoStork dry shippers serve biobank sample transport as well as fertility clinic transfers. For guidance on storage specification for biobanking applications, contact Cryolab.
There is no single correct answer to this question, and any IVF laboratory operating on a fixed topping-up schedule without monitoring actual liquid nitrogen levels in each vessel is taking an unnecessary clinical risk.
Liquid nitrogen consumption in a storage vessel is determined by four variables: the vessel’s rated evaporation rate, the number of times the lid is opened per day, the ambient temperature of the storage room, and the condition of the vessel’s vacuum insulation. All four variables can change over the life of the vessel, which is why monitoring rather than scheduling is the correct approach.
The rule for liquid nitrogen level monitoring in a licensed UK IVF setting is simple: check every vessel, record the level, and top up when the level reaches the threshold specified in your standard operating procedure. Never assume a vessel is fine because it was topped up recently.
Best practice is daily visual inspection of liquid nitrogen levels in every active storage vessel, with levels recorded in a written log. Some laboratories use continuous electronic level monitors that provide real-time data and alarm when levels drop below a set threshold. The log also creates a consumption trend that allows you to spot changes in vessel performance before they become emergencies – a vessel consuming 5 litres per week that previously consumed 2 litres per week is telling you something. For storage vessel selection and alarm system specification, explore the CryoNest storage vessel range or contact Cryolab.
A cryoprotectant is a chemical agent that protects biological cells from damage during the freezing and thawing process. Without cryoprotectants, freezing an embryo or oocyte at any speed would result in catastrophic ice crystal formation inside the cell, destroying the membrane and organelle structures that determine viability.
The mechanism works through osmosis. Cryoprotectants – common examples include dimethyl sulphoxide (DMSO), ethylene glycol and glycerol – are small molecules able to cross the cell membrane. When the cell is placed in a cryoprotectant solution, water moves out by osmosis while cryoprotectant molecules move in. This dehydration reduces the intracellular water available to form ice crystals when temperature drops. In vitrification protocols, this happens in two steps: the equilibration solution begins the process gently, then the vitrification solution completes it rapidly – because high-concentration cryoprotectants are cytotoxic if the embryo is exposed to them too long at room temperature.
The 60 to 90 seconds an embryo spends in vitrification solution before plunging into liquid nitrogen is one of the most time-critical steps in the entire IVF cryopreservation workflow. Too long damages the cell chemically. Too short means insufficient dehydration and ice crystal risk.
The warming process reverses the procedure – warming solutions progressively dilute and remove cryoprotectant while rehydrating the cell. This is why warming solutions should always be matched to the same manufacturer’s vitrification system. The CBS High Security Vitrification Kits include equilibration, vitrification and warming solutions as a matched, validated system. For protocol compatibility questions, contact Cryolab or use CryoGPT.
A denudation pipette is used to remove the cumulus cells surrounding a freshly retrieved oocyte – a step that must happen before ICSI (intracytoplasmic sperm injection) can take place. The inner bore diameter is the specification that matters most, and getting it wrong creates clinical problems that cannot be corrected mid-procedure.
After egg retrieval, each oocyte is surrounded by cumulus granulosa cells that must be removed before the embryologist can assess oocyte maturity and proceed with ICSI. The oocyte is drawn in and out of the pipette bore repeatedly, with the shear force gently stripping cumulus cells away without damaging the oocyte itself. A bore too wide provides insufficient shear force – cumulus cells are not stripped cleanly. A bore too narrow risks damaging the zona pellucida or the oocyte itself.
Denudation pipette specification is one of those consumable decisions that gets made once during laboratory setup and then rarely revisited. It should be revisited when a new embryologist joins, when switching pipette suppliers, or when oocyte quality metrics change – because bore diameter tolerances vary between manufacturers even when the nominal specification is the same.
Standard denudation pipettes typically have inner bore diameters in the range of 140 to 170 micrometres, depending on local protocol preferences and microscope system. Cryolab’s pipette range covers the standard bore sizes used in UK IVF practice, in both straight-cut and fire-polished tip configurations. Before switching pipette format, confirm bore diameter compatibility with your current validated protocol. Contact the Cryolab team for specification advice.
A sperm bank has different operational requirements from a fertility clinic, and those differences should be reflected in how a cryogenic storage supplier is evaluated. The volumes are higher, the regulatory scrutiny is intense, the chain-of-custody requirements are demanding, and donor identification systems must function flawlessly over storage periods that can extend for decades.
The first thing a UK sperm bank should establish is whether the supplier genuinely understands the sector. A supplier who serves industrial cryogenic storage alongside sperm banking is a different proposition from a specialist with 40 years of working with licensed UK fertility and reproductive storage settings. HFEA compliance, donor code management, sample matching across extended storage periods, IATA transport for donor samples dispatched to receiving clinics – these questions require a supplier whose team can engage with them meaningfully.
The consumable supply relationship for a UK sperm bank is not a catalogue exercise. It is a clinical partnership. The right supplier should be able to advise on traceability configuration, not just provide a price list for straws and visotubes.
For storage, the CryoNest range suits high-volume sperm bank storage with canister organisation that makes donor sample retrieval efficient. For dispatch, the CryoStork V10 is preferred for multi-patient batch deliveries. The CBS High Security Straw system with coloured ID jackets provides donor identification at the individual straw level. Cryolab holds ISO 9001:2015 and has been supplying licensed UK sperm banks for over 40 years. Contact us to discuss your requirements.
Liquid nitrogen storage vessels maintain embryos, oocytes, and sperm at -195.8°C — the boiling point of liquid nitrogen at atmospheric pressure. At this temperature, all enzymatic activity and cellular metabolism ceases completely, meaning biological material can remain viable indefinitely provided the liquid nitrogen level is maintained.
Why -195.8°C matters in practice
The figure is not approximate. Embryologists working with cryogenic storage tanks need to understand that temperature uniformity within the vessel depends on where in the tank samples are stored. Samples held in the vapour phase above the liquid nitrogen surface sit at temperatures between -150°C and -190°C — warmer than the liquid phase, and subject to greater fluctuation during lid opening or LN2 refill cycles.
For vitrified oocytes and embryos, vapour-phase storage carries a measurable rewarming risk during access events. High-security tanks with narrow neck openings and automated LN2 replenishment systems reduce this risk by limiting temperature excursion during routine inventory checks.
How this affects equipment selection
Cryopreservation equipment for IVF use must be specified for liquid-phase storage of embryos, with vapour-phase use reserved for longer-term biobank archiving where access frequency is low. Tank capacity, neck diameter, static evaporation rate, and LN2 hold time all affect whether a vessel maintains -195.8°C consistently across its full sample inventory.
Cryolab Ltd supplies liquid nitrogen storage vessels to NHS fertility departments, private IVF clinics, and sperm banks across the UK. For equipment specifications or to discuss your lab’s storage configuration, visit cryolab.co.uk.
Vitrification flash-freezes biological material by plunging it directly into liquid nitrogen, achieving cooling rates exceeding 10,000°C per minute. Slow freezing uses a controlled-rate freezer to lower temperature gradually at 0.3°C to 1°C per minute. The critical difference is ice crystal formation: vitrification produces a glass-like solid state with no ice, while slow freezing — if not precisely controlled — risks intracellular ice that damages cell membranes.
Why vitrification became the clinical standard
ASRM data shows vitrified oocyte survival rates consistently above 80%, compared to 60-70% with slow cooling. The technique is now the dominant method in UK IVF laboratories for oocytes and blastocysts. For sperm, slow freezing with glycerol-based cryoprotectants remains common practice because sperm tolerate ice formation better than eggs and embryos.
The equipment requirements differ considerably. Vitrification requires high-concentration cryoprotectant solutions, specialised loading devices (Cryotop, Cryolock, CBS High Security Straw), and immediate immersion in liquid nitrogen. A controlled-rate freezer is required for slow freezing protocols.
Storage after freezing is identical
Once frozen, vitrified and slow-frozen samples both require storage in liquid nitrogen vessels at -195.8°C. The storage tank specification is the same regardless of the freezing method used.
Cryolab stocks cryopreservation equipment and consumables for both vitrification and slow-cooling protocols. Call the team on 01243 781 121 or visit cryolab.co.uk for a full product listing.
In the UK, sperm can be stored for up to 55 years under the Health and Care Act 2022, which came into force on 1 July 2022. This extended the previous 10-year maximum and applies to sperm, eggs, and embryos stored at licensed clinics. Storage beyond the initial consent period requires written renewal from the donor every 10 years up to the 55-year limit.
What this means for storage infrastructure
A 55-year storage liability requires robust, auditable cryogenic storage infrastructure. Clinics and sperm banks holding long-term specimens need tanks with documented service histories, reliable LN2 supply chains, and continuous temperature monitoring — not just because it is good laboratory practice, but because HFEA inspection will scrutinise storage records across the full duration of consent.
Physical viability at -195.8°C
The 55-year limit is a regulatory ceiling, not a biological one. Sperm stored at -195.8°C in sealed cryovials or straws show no measurable degradation over time when temperature is maintained consistently. Published case studies document successful pregnancies from sperm stored for over 20 years. The limiting factor is always equipment failure or LN2 loss, not the biology.
Biobank storage for longer-term archiving
Research institutions and biobanking facilities holding non-clinical specimens may store indefinitely under different regulatory frameworks. The 55-year limit applies specifically to specimens stored at HFEA-licensed premises.
Cryolab supplies semen storage tanks and cryogenic vessels to UK sperm banks and andrology units. Visit cryolab.co.uk or call 01243 781 121 for tank specifications and hold-time data.
A dry shipper is a cryogenic transport vessel pre-charged with liquid nitrogen absorbed into a porous internal matrix, typically an aluminium silicate or zeolite adsorbent. When the matrix is saturated, the vessel holds samples at cryogenic temperatures (below -150°C) during transport without any free liquid nitrogen present — which is why it can be shipped by air under IATA P650 regulations as a non-hazardous dangerous goods exemption.
The charging process
Before use, a dry shipper must be charged by filling it with liquid nitrogen and allowing the internal matrix to absorb fully — typically 4 to 8 hours depending on vessel size. Once charged, the free LN2 is tipped out. The vessel then holds temperature through slow release of absorbed nitrogen as it evaporates, giving a hold time of 7 to 14 days depending on ambient temperature and vessel model.
Clinical applications
Cryogenic dry shippers are used in IVF for inter-clinic embryo transfers, donor sperm transport from licensed banks, oocyte transport in donor programmes, and research sample courier between sites. They are the only compliant method for transporting viable cryopreserved reproductive material by air.
Key specification points
Dry shippers are not equivalent to storage dewars. They carry smaller inventories, have shorter hold times, and are not suitable as permanent storage vessels. For fixed laboratory storage, a conventional liquid nitrogen tank is required.
Cryolab stocks cryogenic dry shippers for inter-clinic and research transport applications. Call 01243 781 121 or visit cryolab.co.uk for current models and hold-time specifications.
Liquid nitrogen expands to approximately 700 times its volume when it vaporises at room temperature. In an enclosed laboratory, this expansion rapidly displaces oxygen. The HSE sets the safe minimum oxygen concentration in a working environment at 19.5%. Below this threshold, cognitive impairment begins. Below 16%, loss of consciousness can occur within minutes without warning.
Why IVF labs are particularly exposed
Cryopreservation equipment rooms in IVF units typically hold multiple large-capacity storage tanks, sometimes alongside LN2 top-up vessels and transport dewars. A single 35-litre tank failure or undetected slow leak in a poorly ventilated room can breach the 19.5% threshold before anyone working in the space notices any symptoms.
HSE compliance requirements
Under HSE guidance (EH40 and COSHH regulations), any room where liquid nitrogen is stored or used must have a fixed oxygen depletion monitor with audible and visual alarms set at 19.5% and 18% thresholds. Personal alarms are a secondary control, not a substitute for fixed monitors. Ventilation must be calculated to handle the worst-case LN2 evaporation scenario.
Practical risk reduction
Decanting LN2 should always be done with the door open and with two people present. Staff entering a storage room after any period of closure should check the oxygen monitor reading before entering. Annual inspection of tank integrity, valves, and safety relief devices reduces the probability of undetected leaks.
Cryolab supplies liquid nitrogen storage tanks with documented safety specifications to NHS fertility units and private IVF clinics. Visit cryolab.co.uk for equipment details or to speak to the team about safe storage configuration.
A cryovial is a small, screw-cap or push-cap plastic tube designed to store biological material at cryogenic temperatures, typically down to -196°C. In IVF and reproductive medicine, cryovials are used to store sperm samples, testicular tissue, ovarian cortex fragments, and research cell lines. Standard sizes are 1.2 ml (the most common in andrology), 1.8 ml, 2 ml, and 5 ml, with external-thread caps preferred in clinical settings to prevent contamination between stored specimens.
Cryovials versus straws in IVF
Embryos and oocytes in UK clinical IVF are almost exclusively stored in closed vitrification devices — CBS High Security Straws or equivalent — rather than cryovials, because straws allow faster cooling rates and tighter inventory control on embryo identity. Cryovials are the standard container for sperm, testicular biopsy material, and biobank cell lines, where volumes are larger and the vapour-phase storage risk is lower.
Compatibility with storage tanks
Cryovials are held in cryogenic canes inside standard goblets, which slot into the canisters of a liquid nitrogen storage vessel. Labelling with cryogenic-rated labels or direct embossing is essential — standard adhesive labels fail at -196°C and detach, creating an identification risk inside the tank.
Biobanking applications
Large-scale biobanking operations use barcoded cryovials with matrix tube racks and automated retrieval systems. In research settings, 2D barcoded cryovials are standard to support inventory management at scale.
Cryolab supplies cryovials and cryogenic consumables to UK fertility clinics, NHS andrology units, and research biobanks. Visit cryolab.co.uk or call 01243 781 121 for a full consumables catalogue.
Biobanking refers to the long-term, systematic storage of biological specimens — tissue samples, cell lines, blood derivatives, gametes, and genetic material — for research, future therapeutic use, or population-level studies. Clinical cryostorage in an IVF context is regulated by the HFEA, purpose-specific, and tied to individual patient consent cycles. Biobanking operates under broader governance frameworks including the Human Tissue Act 2004, Research Ethics Committee approval, and institutional biobank policies.
Scale and infrastructure differences
A clinical IVF storage room might hold 2 to 10 large liquid nitrogen tanks, each with a defined patient inventory. A biobank facility may hold hundreds of vessels, automated liquid handling systems, and real-time inventory management software tracking millions of individual samples. The cryopreservation equipment requirements at that scale are categorically different.
Temperature monitoring and audit trail
Both clinical and biobank settings require continuous temperature monitoring with data logging. For biobanking specifically, the audit trail — recording every access event, temperature excursion, and LN2 refill — must be maintained for the duration of sample storage, which in population cohort studies can exceed 30 years.
Where cryolab.co.uk fits
Cryolab supplies biobanking equipment to UK university research facilities and NHS-affiliated biorepositories, including high-capacity storage vessels, monitoring hardware, and cryogenic consumables suited to large-volume, long-duration storage programmes.
For biobanking equipment, vessel specifications, and consultancy on storage system design, visit cryolab.co.uk/biobanking/ or call the team on 01243 781 121.
When handling liquid nitrogen, the minimum PPE required under HSE COSHH guidelines is: cryogenic gloves rated for -196°C (not standard cold-store gloves), a full-face shield or safety goggles, a lab coat or long-sleeved protective clothing, and closed-toe shoes. If decanting from a large bulk supply into smaller dewars, an apron rated for cryogenic splash is also required.
Why standard gloves are insufficient
Household or catering cold-store gloves give no protection against cryogenic temperatures or liquid nitrogen splash. Cryogenic gloves for laboratory use must meet EN 511 standards and be long enough to cover the wrist and lower forearm. In the event of a splash, the glove should be removed immediately — do not try to shake liquid nitrogen off, as it will pool in the fabric and cause a contact burn.
Eye protection priority
Liquid nitrogen splashing into unprotected eyes causes immediate freeze injury. A full-face shield gives more protection than goggles alone during decanting operations. Goggles without ventilation can fog during cold work; indirect-vent chemical splash goggles are the practical compromise for routine laboratory use.
Integration with tank safety design
Well-designed liquid nitrogen storage vessels with narrow necks and low static evaporation rates reduce the frequency and volume of LN2 handling required. Fewer fill events means reduced PPE exposure per working week.
Cryolab supplies cryogenic storage equipment designed to minimise LN2 handling frequency. Visit cryolab.co.uk for tank specifications or call 01243 781 121 to speak to the technical team.
Hold time is the number of days a liquid nitrogen storage tank can maintain its contents at or below -195.8°C from a full LN2 fill without any further replenishment. It is determined by the vessel’s static evaporation rate — measured in litres of LN2 lost per day — relative to the tank’s total LN2 capacity. A well-insulated 35-litre tank with a static evaporation rate of 0.08 L/day has a theoretical hold time of approximately 437 days.
Why hold time matters operationally
For an IVF clinic or sperm bank without automated LN2 replenishment, hold time determines the maximum safe interval between manual top-ups. A tank approaching its hold time limit without LN2 replenishment will begin warming, first in the vapour phase, then in the liquid phase. For vitrified embryos stored in the vapour phase, temperature excursions above -130°C (the glass transition temperature) may cause devitrification — a return to an ice-containing state — with potential damage to cellular structures.
Comparing tank specifications
When selecting cryogenic storage tanks, hold time should be evaluated alongside neck diameter, working capacity (the volume available for sample storage after LN2 fill), and canister configuration. A tank with a long hold time but a wide neck may lose more LN2 per access event than the static evaporation data suggests.
Automated monitoring and top-up systems
High-security cryopreservation equipment installations use continuous LN2 level sensors with automated supply from a bulk tank, removing hold time as a risk variable entirely. This is the standard configuration in purpose-built embryology suites.
Cryolab supplies liquid nitrogen vessels across a range of capacities and static evaporation rates. Contact the team on 01243 781 121 or visit cryolab.co.uk for full specifications and hold-time data.
A liquid nitrogen storage tank is a fixed-position dewar vessel designed to store biological specimens at -195.8°C for months or years. It holds free liquid nitrogen that samples are submerged in or suspended above. A cryogenic dry shipper is a transport vessel where liquid nitrogen is absorbed into a porous internal matrix — no free liquid is present — allowing it to be shipped by air under IATA P650 regulations. The two serve different functions and are not interchangeable.
Key operational differences
Storage tanks are rated for static performance over long periods. Specifications that matter are capacity, static evaporation rate, neck diameter, and canister count. Dry shippers are rated for transport performance: hold time in hours or days, temperature maintenance under movement and orientation change, and IATA compliance documentation.
A storage tank can hold several thousand specimens across multiple canisters. A dry shipper holds a much smaller working inventory — typically enough for a single patient transfer or a courier consignment — and must be recharged after each use.
Regulatory classification
Dry shippers are classified under IATA Dangerous Goods Regulations Section II of Packing Instruction P650 as a non-restricted cryogenic article when no free liquid is present. Standard liquid nitrogen dewars cannot be shipped by air in this way.
Choosing the right vessel
For in-house cryogenic storage in an IVF clinic or sperm bank, a fixed storage dewar is correct. For inter-clinic embryo transport, donor sperm courier, or any air shipment, a validated dry shipper is required. Some biobanking operations use both — bulk storage on-site, dry shippers for outbound distribution.
Cryolab stocks both cryogenic storage tanks and dry shippers for IVF, andrology, and research applications. Visit cryolab.co.uk or call 01243 781 121 for model comparisons and pricing.
A controlled rate freezer is a programmable cryogenic instrument that lowers the temperature of biological material at a precise, pre-set rate — typically 0.3°C to 1°C per minute — under microprocessor control. In IVF, it is used for slow-protocol sperm cryopreservation, testicular tissue freezing, and some embryological research applications where vitrification is not the appropriate method.
How a controlled rate freezer works
The sample is placed in a sealed chamber, and liquid nitrogen vapour is introduced in controlled pulses to drive the cooling curve. The instrument monitors temperature via a thermocouple and adjusts LN2 delivery to hold the programmed rate. Seeding — the deliberate induction of ice crystal formation at a defined temperature — is performed manually or automatically to prevent supercooling.
Controlled rate freezing versus vitrification
For oocytes and blastocysts, vitrification has largely replaced slow cooling in UK clinical IVF because of superior post-thaw survival rates. Controlled rate freezers remain the standard for sperm, where the larger volume and different cell structure make slow cooling more practical. For ovarian cortex and testicular tissue, controlled rate protocols are still widely used because the tissue architecture requires a gentler thermal gradient.
Storage after controlled rate freezing
Once the slow-freeze cycle is complete, samples are transferred to liquid nitrogen storage vessels at -195.8°C for long-term holding. The controlled rate freezer is a processing instrument, not a storage device.
Cryolab supplies cryopreservation equipment and consumables to UK IVF laboratories and andrology units. Visit cryolab.co.uk or call 01243 781 121 for equipment advice.
Ovarian tissue cryopreservation is the surgical removal, freezing, and long-term storage of ovarian cortex strips for future reimplantation. It is used primarily for fertility preservation in patients facing gonadotoxic cancer treatments — chemotherapy or radiotherapy — where there is insufficient time for a full oocyte stimulation cycle before treatment begins. Unlike egg or embryo freezing, it does not require a partner or a stimulation protocol.
The cryopreservation process
Ovarian cortex tissue is dissected into thin strips (typically 1mm thick) in the operating theatre or embryology laboratory, loaded into cryovials or cryogenic straws with a cryoprotectant solution, and either vitrified or slow-frozen using a controlled rate protocol. The choice of method depends on the laboratory’s established validated protocol.
Storage requirements
Stored tissue is held in liquid nitrogen vessels at -195.8°C. Because ovarian tissue is stored for extended periods — sometimes 10 to 20 years in oncofertility cases — the storage vessel specification, LN2 monitoring, and access security are critical. UK storage is governed by the Human Tissue Act 2004 for research material and by HFEA licence where the tissue is stored for reproductive use.
Reimplantation outcomes
Live birth rates following ovarian tissue reimplantation are reported at 30-40% per reimplantation attempt in specialist centres. More than 200 live births have been documented globally from reimplanted cryopreserved ovarian tissue. The technique is now considered established rather than experimental by ESHRE and ASRM.
Cryolab supplies cryogenic storage vessels and consumables for oncofertility and specialist fertility preservation programmes. Visit cryolab.co.uk/cryopreservation/ or call 01243 781 121.
Liquid nitrogen level in a cryogenic storage tank is monitored using one of three methods: a dipstick (a calibrated rod inserted into the neck to measure LN2 depth), a continuous electronic level sensor using a resistive or capacitive probe, or an automated monitoring system linked to a remote alarm and top-up supply. For clinical IVF use, continuous electronic monitoring with remote alarm capability is the standard recommended by HFEA inspection teams.
Why manual dipstick checks are not sufficient alone
A weekly manual dipstick check will not catch a sudden tank failure or an accelerated evaporation event between checks. For cryogenic storage vessels holding patient embryos or sperm, the HFEA expects 24-hour monitoring with audible and remote alarms triggered before LN2 falls to a critical level.
Alarm threshold setting
Alarms should be set at two levels: a warning threshold (typically 30-40% of normal working LN2 depth) giving time for corrective action, and a critical threshold (15-20% depth) triggering immediate response. Both thresholds must be tested and documented as part of the laboratory’s quality management system under ISO 9001 or equivalent.
Integration with automated top-up
High-security cryopreservation equipment installations link level sensors to an automated LN2 supply valve from a bulk storage tank, maintaining level within a defined band without manual intervention. This removes LN2 exhaustion as a failure mode entirely.
Cryolab supplies liquid nitrogen storage tanks and monitoring equipment to NHS fertility units and private IVF clinics across the UK. Visit cryolab.co.uk or call 01243 781 121.
Fertility preservation for cancer patients involves freezing sperm, oocytes, embryos, or gonadal tissue before gonadotoxic cancer treatment begins, with the intention of using the stored material for future reproduction. It is offered as standard of care in UK oncology pathways for patients of reproductive age. The process requires the full range of cryopreservation equipment used in clinical IVF, plus specialist protocols for urgent cases where treatment cannot be delayed.
Sperm banking for male cancer patients
Sperm banking is the fastest and least invasive option for male patients. A semen sample is produced, analysed, cryopreserved using a slow-freeze protocol, and loaded into cryovials or straws for storage in a semen storage tank. The entire process takes 2 to 4 hours, making it compatible with urgent treatment timelines.
Oocyte and embryo freezing for female patients
Female patients require a 10 to 14 day ovarian stimulation cycle before oocyte retrieval, which may delay cancer treatment. Where this is not possible, ovarian tissue cryopreservation can be performed surgically within 24 to 48 hours. Vitrified oocytes are stored using vitrification protocols in liquid nitrogen vessels at -195.8°C.
Long-term storage implications
Cancer patients may store material for 10 to 20 years or longer, particularly those treated in childhood or adolescence. Under the Health and Care Act 2022, storage up to 55 years is permitted at HFEA-licensed premises with consent renewal. Biobanking-grade storage infrastructure is appropriate for these long-duration cases.
Cryolab supplies cryogenic storage equipment and consumables to UK fertility preservation and oncofertility programmes. Visit cryolab.co.uk or call 01243 781 121.
Testicular tissue cryopreservation is the surgical removal and freezing of testicular tissue containing spermatogonial stem cells, used for boys who have not yet reached puberty and face gonadotoxic cancer treatment. Unlike adult sperm banking, prepubertal boys cannot produce ejaculated sperm, so tissue biopsy is the only available fertility preservation option. The technique remains investigational in terms of reimplantation outcomes but is offered at specialist centres in the UK.
The biopsy and cryopreservation process
A small testicular biopsy is taken under general anaesthetic, divided into fragments, loaded into cryovials with a cryoprotectant, and slow-frozen using a controlled rate freezer protocol. Samples are then transferred to liquid nitrogen storage tanks at -195.8°C for indefinite holding pending future use.
Storage duration and regulatory framework
Testicular tissue for reproductive use stored at an HFEA-licensed clinic falls under the Health and Care Act 2022 consent framework and can be stored for up to 55 years with renewal. For research-only tissue held under Human Tissue Act 2004 licence, storage duration is governed by the research ethics approval rather than the 55-year reproductive consent limit.
Future use options
Current research focuses on spermatogonial stem cell transplantation back into the testes and in vitro maturation of sperm from the stored tissue. Neither technique has yet resulted in a live birth in humans, though animal models show proof of concept. Boys whose tissue is stored today may be able to use it once these techniques are validated.
Cryolab supplies cryogenic equipment and consumables to UK specialist fertility preservation and paediatric oncofertility units. Visit cryolab.co.uk/cryopreservation/ or call 01243 781 121.
Embryo grading is the visual assessment of embryo quality by an embryologist, used to select the best embryo for transfer and to decide which embryos are suitable for cryopreservation. At the blastocyst stage (day 5 or 6 of development), embryos are graded using the Gardner grading system, which assesses expansion (1-6), inner cell mass quality (A, B, or C), and trophectoderm quality (A, B, or C). A 4AA blastocyst, for example, is a fully expanded blastocyst with excellent inner cell mass and trophectoderm.
Which embryos are frozen
Embryos assessed as suitable for cryopreservation — typically grade 3BB or above at blastocyst stage — are vitrified using vitrification protocols and loaded into closed carriers (CBS High Security Straws or equivalent) for storage in liquid nitrogen vessels at -195.8°C. Lower-grade embryos may be cultured further or discarded according to the clinic’s protocol and patient consent.
Does grade affect storage outcome?
Embryo grade does not affect storage outcome — once vitrified at -195.8°C, all embryos are equally stable. Grade affects post-thaw survival and implantation probability, but the cryopreservation process itself does not distinguish between grades. A lower-grade embryo stored correctly is as physically intact after thawing as a higher-grade one.
Inventory management implications
Clinics storing embryos of mixed grades need clear inventory management within the storage tank — canisters, goblets, and straws must be labelled to identify patient, embryo ID, grade, and date of freeze. This is a biobanking discipline as much as a clinical one.
Cryolab supplies liquid nitrogen storage vessels, vitrification consumables, and cryogenic accessories to UK IVF clinics. Visit cryolab.co.uk or call 01243 781 121.
Frozen embryo transfer (FET) success rates in UK IVF average 27% live birth per transfer for patients under 35, falling to around 17% for patients aged 38-39 and 8% for patients over 42, based on HFEA data for 2021 cycles. These figures reflect transfers using the patient’s own frozen embryos. Donor embryo transfers show higher rates because donor selection filters for embryo quality.
Why frozen transfers now rival fresh transfers
Advances in vitrification have brought post-thaw survival rates above 90% in well-run IVF laboratories, meaning the embryo that goes back in a frozen cycle is almost always the same quality as it was at the point of freezing. Some studies show FET outcomes exceeding fresh transfer outcomes, because the uterine environment in a frozen cycle (without the hormonal effects of stimulation) may be more receptive.
Factors that affect FET success
Patient age at the time of freezing is the dominant factor — the eggs used to create the embryo determine genetic quality, and age at freeze is what matters, not age at transfer. Embryo grade, endometrial preparation protocol, and the number of previous failed transfers also influence outcome.
The role of storage quality
Post-thaw survival — and therefore transfer success — depends partly on storage quality. Temperature excursions in the storage vessel, caused by LN2 loss or repeated access events without adequate neck insulation, can degrade vitrified embryos before the thaw cycle even begins.
Cryolab supplies cryopreservation equipment and storage vessels to UK fertility clinics. Visit cryolab.co.uk or call 01243 781 121.
A semen analysis is a laboratory test that assesses sperm quality across five core parameters: volume (normal range 1.4-7.6 ml per ejaculate), concentration (16 million sperm per ml or above), total motility (42% or above), progressive motility (30% or above), and morphology (4% normal forms or above by Kruger strict criteria). These reference ranges are set by the World Health Organisation (WHO 2021 sixth edition) and are used by UK andrology laboratories as the standard for clinical reporting.
How semen analysis is performed
A fresh ejaculate sample is produced at the clinic or transported within 60 minutes at body temperature. After liquefaction (typically 15-30 minutes at room temperature), the sample is assessed using a haemocytometer or CASA (Computer-Assisted Sperm Analysis) system. Morphology is assessed on a fixed, stained slide under oil immersion microscopy.
Connection to cryopreservation decisions
Semen analysis results directly inform whether a sample is suitable for banking and which cryopreservation protocol to use. Severely oligospermic samples (below 1 million sperm per ml) may require density gradient preparation before freezing. Samples are stored in cryovials or straws in semen storage tanks at -195.8°C after cryoprotectant addition.
Repeat testing before cryopreservation
Andrology guidelines recommend at least two semen analyses before drawing conclusions about baseline sperm quality, as significant intra-individual variation is normal. For fertility preservation banking, the first analysis informs how many vials to freeze; the result does not prevent banking even if parameters are below reference range.
Cryolab supplies andrology laboratory equipment, cryovials, and semen storage tanks to UK NHS and private andrology units. Visit cryolab.co.uk or call 01243 781 121.
A sperm bank is a facility licensed by the HFEA specifically to recruit, screen, process, store, and distribute donor sperm. Its primary function is holding a donor inventory for use by fertility clinics. A fertility clinic is licensed to perform IVF, IUI, and other assisted reproductive treatments using patients’ own gametes or donor material sourced from a licensed sperm bank. The two are distinct HFEA licence categories, though some fertility clinics operate an in-house donor sperm programme under a combined licence.
Storage infrastructure differences
A dedicated sperm bank holds large volumes of donor inventory across many semen storage tanks, with each donor’s samples held separately and tracked by unique donor ID. Fertility clinics hold patient-specific samples in cryogenic storage vessels alongside embryos and oocytes. A sperm bank needs rapid retrieval and dispatch logistics; a fertility clinic needs patient-level sample security and audit trails for HFEA inspection.
Regulatory requirements
Both sperm banks and fertility clinics operate under HFEA licence and are subject to the Human Fertilisation and Embryology Act 1990 (as amended). Donor sperm must pass a minimum 6-month quarantine period with repeat donor STI and genetic screening before release for use. All storage must meet HFEA Code of Practice requirements for cryopreservation standards.
Cryolab supplies cryogenic storage equipment to UK sperm banks and fertility clinics. Visit cryolab.co.uk or call 01243 781 121 for storage vessel specifications and pricing.
A liquid nitrogen storage tank should be inspected annually as a minimum, covering: vacuum integrity (checked by measuring static evaporation rate against the manufacturer’s specification), neck condition (checking for ice build-up, cracks, or deformation), canister and withdrawal rod integrity, pressure relief valve function, and LN2 level sensor calibration. Any tank showing a static evaporation rate more than 20% above its specification should be flagged for replacement.
Vacuum degradation over time
The insulation performance of a cryogenic storage vessel depends on the vacuum maintained between its inner and outer walls. Over years of use, outgassing from internal materials can degrade this vacuum, increasing heat ingress and LN2 consumption. A tank that requires noticeably more frequent top-ups than when new is likely losing vacuum. Once vacuum is lost, the tank cannot be economically repaired and must be replaced.
Cleaning and decontamination
Tanks should be emptied and warmed to room temperature periodically — typically every 2-5 years, or when changing sample inventory — for inspection and cleaning. Any biological contamination on internal surfaces should be decontaminated following HFEA and HSE guidance before the tank is returned to service. This process requires a quarantine plan for the displaced samples.
Documentation for HFEA inspection
Service records, temperature logs, LN2 consumption data, and alarm test records must all be maintained as part of the quality management system. HFEA inspectors will review storage maintenance records as part of the licence inspection. Cryolab holds ISO 9001:2015 certification and provides equipment with full technical documentation to support this audit trail.
Cryolab holds ISO 9001:2015 certification and supplies liquid nitrogen storage tanks with full technical documentation to UK fertility clinics and sperm banks. Visit cryolab.co.uk or call 01243 781 121.
Preimplantation genetic testing (PGT) is the biopsy and chromosomal or genetic analysis of an embryo at the blastocyst stage before transfer. It is used to identify chromosomally normal embryos (PGT-A), embryos free from a specific inherited condition (PGT-M), or embryos without structural chromosomal rearrangements (PGT-SR). In the UK, PGT-M and PGT-SR require HFEA licence approval for the specific condition being tested.
How PGT affects the cryopreservation workflow
After biopsy on day 5 or 6, embryos cannot be transferred immediately — the biopsy sample must be sent to a genetics laboratory, which takes 2 to 4 weeks for results. All biopsied embryos are therefore vitrified using vitrification protocols and held in liquid nitrogen storage at -195.8°C while awaiting results. Only embryos reported as suitable are warmed for transfer.
Storage implications for PGT cycles
PGT cycles generate a larger cohort of vitrified embryos held simultaneously than standard IVF cycles, because all embryos are frozen before any transfer occurs. This increases the storage inventory per patient and places greater demand on tank capacity, canister organisation, and sample tracking within the cryopreservation system.
Embryos awaiting results
Embryos biopsied but not yet reported are held in a quarantine section of the storage tank until results are received. Those reported as unsuitable are discarded with patient consent. Suitable embryos remain in storage until the patient is ready for transfer, which may be months or years later.
Cryolab supplies liquid nitrogen storage vessels and cryopreservation consumables to UK IVF clinics running PGT programmes. Visit cryolab.co.uk or call 01243 781 121.
Egg freezing — formally oocyte cryopreservation — is the collection, vitrification, and storage of unfertilised eggs for future use. It allows women to preserve their reproductive potential before age-related decline, before cancer treatment, or before social circumstances are right for family building. In the UK, frozen eggs can be stored for up to 55 years under the Health and Care Act 2022 at an HFEA-licensed clinic, with consent renewed every 10 years.
Success rates by age
The most important factor in egg freezing success is the age at which eggs are frozen. HFEA data shows live birth rates per egg frozen of approximately 5-7% for women under 35, falling to 2-3% per egg for women over 38. Most clinics recommend freezing at least 10 to 15 mature eggs to achieve a reasonable cumulative live birth probability, which typically requires one or two stimulation cycles.
The vitrification process
Retrieved oocytes are loaded into high-security closed carriers and plunged directly into liquid nitrogen using vitrification protocols that achieve cooling rates exceeding 10,000°C per minute. Post-thaw survival rates in experienced laboratories exceed 80%. Eggs are stored in liquid nitrogen vessels at -195.8°C alongside the clinic’s embryo inventory.
Elective versus medical egg freezing
Medical egg freezing (before cancer treatment or other gonadotoxic therapy) is funded by some NHS trusts. Elective social egg freezing is self-funded. Both use identical cryopreservation protocols and storage infrastructure.
Cryolab supplies vitrification consumables and liquid nitrogen storage equipment to UK fertility clinics offering egg freezing programmes. Visit cryolab.co.uk or call 01243 781 121.
The terms liquid nitrogen dewar and cryogenic tank are often used interchangeably, but they refer to the same category of vessel — a double-walled, vacuum-insulated container designed to hold liquid nitrogen at -195.8°C. The word dewar comes from Sir James Dewar, who developed the vacuum flask principle in 1892. In laboratory and clinical use, both terms describe vessels ranging from small 2-litre bench dewars to large 35-litre or 50-litre storage tanks holding thousands of cryopreserved specimens.
Functional distinctions within the category
Open dewars (wide-neck, no lid) are used for bench work and short-term LN2 dispensing. Closed storage dewars with narrow necks and canisters are designed for long-term cryopreservation of biological material. Dry shippers are dewars with an absorbent matrix for transport. Each has a different specification for neck diameter, hold time, and working capacity.
Choosing the right vessel
For IVF embryo and sperm storage, a narrow-neck closed storage dewar with canister organisation is the correct choice. For LN2 dispensing, a small open dewar is appropriate. For inter-clinic sample transport, a dry shipper is required. None of these is a substitute for the others.
Capacity and specification range
Cryolab supplies liquid nitrogen storage tanks across a range of capacities from small clinic vessels to high-capacity biobanking units.
Cryolab stocks a full range of liquid nitrogen dewars and storage vessels for IVF, andrology, and research use. Visit cryolab.co.uk or call 01243 781 121 for model comparisons.
The most widely used cryoprotectant in sperm freezing is glycerol, typically in a ready-to-use extender solution such as Test-Yolk Buffer (TYB) or BioXcell. These extenders combine glycerol (usually at 6-15% final concentration) with egg yolk or plant-derived proteins, buffers, and antibiotics to protect sperm during the slow-freeze process. Glycerol acts as a penetrating cryoprotectant, entering the sperm cell and preventing intracellular ice formation during freezing and thawing.
How the cryoprotectant is applied
Semen is mixed with the cryoprotectant extender at a defined ratio (typically 1:1 v/v), incubated briefly to allow equilibration, then loaded into cryovials or 0.25 ml or 0.5 ml straws before the slow-freeze protocol, and stored at -195.8°C in a semen storage tank.
Cryoprotectant toxicity
Glycerol is toxic to sperm at room temperature over time, so equilibration steps are kept short (5 to 10 minutes) and samples are frozen promptly after mixing. Higher glycerol concentrations improve cryoprotection but increase toxicity risk.
Oocyte vitrification uses different cryoprotectants
For oocyte and embryo vitrification, ethylene glycol and dimethyl sulphoxide (DMSO) are used at much higher concentrations (15-30% combined). Glycerol is not appropriate for oocyte vitrification because it does not penetrate the zona pellucida effectively.
Cryolab supplies sperm cryopreservation consumables, cryovials, and semen storage tanks to UK andrology units. Visit cryolab.co.uk or call 01243 781 121.
The Human Fertilisation and Embryology Act 1990 (as amended by the Human Fertilisation and Embryology Act 2008 and the Health and Care Act 2022) is the primary legislation governing IVF, embryo research, and the storage of human gametes and embryos in the UK. It established the HFEA as the independent regulator, with powers to licence, inspect, and close fertility clinics and research centres.
What the Act requires for cryostorage
Under the HFE Act, no person may store human gametes or embryos without an HFEA licence. Licensed premises must maintain cryopreservation standards meeting the HFEA Code of Practice, specifying requirements for storage vessel quality, temperature monitoring, consent management, and traceability of every stored specimen.
Consent framework
Written consent is required from all gamete providers before storage begins. Under the Health and Care Act 2022, the maximum storage period is 55 years, with consent renewal required every 10 years.
Implications for storage infrastructure
HFEA inspection teams review whether storage vessels are fit for purpose, whether monitoring and alarm systems are in place and tested, and whether access to stored material is controlled and documented. Suppliers holding ISO 9001:2015 certification — such as Cryolab — provide equipment with the technical documentation that supports HFEA audit trails.
Cryolab holds ISO 9001:2015 certification and supplies cryogenic storage equipment to HFEA-licensed fertility clinics and sperm banks across the UK. Visit cryolab.co.uk or call 01243 781 121.
Intrauterine insemination (IUI) is a fertility treatment in which prepared sperm are inserted directly into the uterus around the time of ovulation, bypassing the cervix. Unlike IVF, fertilisation occurs naturally inside the body rather than in a laboratory dish. IUI is used for unexplained infertility, mild male factor infertility, single women using donor sperm, and same-sex female couples. Success rates per cycle average 10-15% for women under 35 using fresh or thawed donor sperm.
Sperm preparation for IUI versus IVF
For IUI, sperm must be washed and concentrated using density gradient centrifugation or swim-up preparation to remove seminal plasma, dead cells, and debris. The prepared sample — typically 0.3 to 1 ml of concentrated motile sperm — is loaded into a thin catheter for uterine insertion. For IVF, sperm preparation is similar but the volume and concentration requirements differ.
Donor sperm storage for IUI
Donor sperm for IUI arrives from an HFEA-licensed sperm bank in pre-prepared, cryopreserved straws or cryovials, stored in semen storage tanks at -195.8°C until the day of use.
IUI versus IVF success comparison
IVF success rates are approximately twice those of IUI per cycle, but IUI is less invasive, less expensive, and appropriate as a first-line treatment in many cases. NICE guidelines recommend up to 6 cycles of IUI before moving to IVF for eligible patients.
Cryolab supplies semen storage tanks, cryovials, and andrology consumables to UK fertility clinics and sperm banks. Visit cryolab.co.uk or call 01243 781 121.
Cryogenic vapour phase storage refers to holding biological specimens in the space above the liquid nitrogen surface inside a storage vessel, rather than submerged directly in the liquid. In vapour phase, samples are exposed to temperatures between -130°C and -190°C depending on their height above the LN2 surface. Liquid phase storage (submerged at -195.8°C) is colder, more stable, and the standard for most clinical IVF applications.
Why vapour phase is used
The primary reason to use vapour phase storage is biosafety. Liquid nitrogen can harbour and transmit pathogens if contaminated samples leak into the shared LN2 pool. For high-risk specimens, vapour phase storage in sealed containers prevents cross-contamination between patients’ material stored in the same cryogenic tank.
Temperature stability concerns
The critical risk in vapour phase storage is temperature excursion during access events. Every time the lid is opened, the vapour phase temperature rises — potentially above -130°C, the glass transition temperature of vitrified material, at which point devitrification can occur. High-security vessels with narrow necks and insulated lids significantly reduce this risk.
Vapour phase in biobanking
Large-scale biobanking operations often use vapour phase tanks for long-term archiving where cross-contamination risk management is a priority. For clinical IVF embryo storage, liquid phase in sealed, individually identified straws remains the standard in the majority of UK clinics.
Cryolab supplies both liquid phase and vapour phase cryogenic storage vessels to UK fertility clinics and research biobanks. Visit cryolab.co.uk or call 01243 781 121 for specifications.
The European Society of Human Reproduction and Embryology (ESHRE) is the principal professional and scientific organisation for reproductive medicine in Europe, with over 9,000 members across more than 100 countries. It publishes clinical practice guidelines, organises the largest annual reproductive medicine congress in the world, and coordinates the European IVF Monitoring (EIM) consortium, which collects outcome data from fertility clinics across 41 European countries.
ESHRE guidelines and cryopreservation
ESHRE publishes evidence-based guidelines on vitrification, ovarian stimulation, embryo transfer, and fertility preservation that are widely adopted by UK IVF clinics alongside HFEA Code of Practice requirements. These guidelines specify best practice for cryopreservation protocols, warming procedures, and quality indicators including post-thaw survival rates.
EIM data and UK IVF benchmarking
ESHRE’s EIM consortium allows UK clinics to benchmark their outcomes — including frozen embryo transfer success rates and cryosurvival rates — against European averages, using this data to assess whether storage and laboratory protocols are performing to international standards.
Cryolab and ESHRE
Cryolab’s founder Paul Hague has attended 42 consecutive ESHRE annual congresses, giving Cryolab one of the longest continuous presences of any UK supplier at the world’s leading IVF conference. This depth of engagement informs the equipment and consumable recommendations Cryolab makes to its clinic customers.
Cryolab supplies cryopreservation equipment and consumables aligned with ESHRE and HFEA standards to UK fertility clinics. Visit cryolab.co.uk or call 01243 781 121.
In a fresh embryo transfer, an embryo created during an IVF cycle is transferred to the uterus 3 to 5 days after egg collection, without any freezing step. In a frozen embryo transfer (FET), embryos are vitrified after creation and stored in liquid nitrogen, then warmed and transferred in a subsequent cycle. The majority of UK IVF cycles now include at least one frozen transfer, and freeze-all strategies are increasingly common.
Clinical advantages of frozen transfer
The uterine environment during an ovarian stimulation cycle is hormonally abnormal. A frozen cycle allows the uterus to return to its natural state before transfer, which some studies show improves implantation rates. For patients at risk of ovarian hyperstimulation syndrome (OHSS), a freeze-all strategy avoids the risk of exacerbating OHSS with a fresh transfer.
The role of vitrification quality
The success of a frozen transfer depends on the quality of the initial vitrification, the stability of the storage vessel over the storage period, and the warming protocol. Post-thaw survival above 90% is achievable in well-run laboratories using validated protocols and properly maintained equipment.
Cumulative success across fresh and frozen transfers
Modern IVF reporting focuses on cumulative live birth rate — the total probability across all fresh and frozen transfers from a single egg collection. This depends heavily on how many good-quality embryos are available for cryopreservation and storage.
Cryolab supplies vitrification consumables and liquid nitrogen storage tanks to UK IVF clinics. Visit cryolab.co.uk or call 01243 781 121.
A cryogenic canister is a cylindrical metal container — typically aluminium — that hangs inside a liquid nitrogen storage tank from a central withdrawal rod or rack system. Each canister holds goblets, which hold cryogenic canes. Straws, cryovials, and vitrification devices are loaded onto the canes. This hierarchical organisation — tank, canister, goblet, cane, straw — gives every stored specimen a unique location address within the inventory.
Standard canister configurations
A typical 35-litre cryogenic storage tank holds 6 canisters. Each canister holds 5 goblets, each goblet holds 5 canes, and each cane holds 10 straws — giving a theoretical maximum of 1,500 straws per tank in a standard configuration.
Inventory management within the tank
Every specimen must be traceable to its canister, goblet, and cane position. In clinical IVF, this is documented in a paper or electronic tank inventory system, updated every time a specimen is added or removed. HFEA inspection teams review inventory records to confirm that no specimen is stored without a corresponding consent form.
Biobanking at scale
Large biobanking operations replace manual canister organisation with automated storage and retrieval systems, using robotics and 2D barcoded cryovials to manage inventories of millions of samples across hundreds of tanks.
Cryolab supplies liquid nitrogen storage tanks, canisters, goblets, canes, and cryogenic consumables to UK fertility clinics and research biobanks. Visit cryolab.co.uk or call 01243 781 121.
Preimplantation genetic testing (PGT) is the biopsy and chromosomal analysis of an embryo at blastocyst stage before transfer. All biopsied embryos are vitrified using vitrification protocols and held in liquid nitrogen storage at -195.8°C while awaiting results — typically 2 to 4 weeks. Only embryos reported as suitable are warmed for transfer.
Storage implications
PGT cycles freeze all embryos before any transfer occurs, increasing inventory demands on the cryopreservation system. Unsuitable embryos are discarded with patient consent; suitable ones remain stored until the patient is ready.
Cryolab supplies LN2 storage vessels and cryopreservation consumables to UK IVF clinics. Visit cryolab.co.uk or call 01243 781 121.
Egg freezing (oocyte cryopreservation) is the collection, vitrification, and storage of unfertilised eggs for future use. In the UK, frozen eggs can be stored for up to 55 years under the Health and Care Act 2022. HFEA data shows live birth rates per egg frozen of approximately 5-7% for women under 35, falling to 2-3% for women over 38.
Storage and process
Retrieved oocytes are vitrified at cooling rates exceeding 10,000°C per minute and stored in liquid nitrogen vessels at -195.8°C. Post-thaw survival rates in experienced laboratories exceed 80%. Both medical and elective social egg freezing use identical cryopreservation protocols.
Cryolab supplies vitrification consumables and LN2 storage equipment to UK fertility clinics. Visit cryolab.co.uk or call 01243 781 121.
The most widely used cryoprotectant in sperm freezing is glycerol, combined in ready-to-use extender solutions such as Test-Yolk Buffer (TYB) or BioXcell at 6-15% final concentration. Glycerol enters the sperm cell and prevents intracellular ice formation during the slow-freeze process. Samples are loaded into cryovials or straws and stored at -195.8°C in a semen storage tank.
Oocyte vitrification differs
For oocyte and embryo vitrification, ethylene glycol and DMSO are used at 15-30% combined concentration. Glycerol is not appropriate for oocytes as it does not penetrate the zona pellucida effectively.
Cryolab supplies sperm cryopreservation consumables and semen storage tanks to UK andrology units. Visit cryolab.co.uk or call 01243 781 121.
The Human Fertilisation and Embryology Act 1990 (as amended by the HFE Act 2008 and Health and Care Act 2022) is the primary UK legislation governing IVF and the storage of human gametes and embryos. It established the HFEA as the independent regulator with powers to licence and inspect fertility clinics. No person may store human gametes or embryos without an HFEA licence.
Consent and storage limits
Written consent is required before storage begins. Under the Health and Care Act 2022, the maximum storage period is 55 years with consent renewal every 10 years. HFEA inspectors review whether storage vessels meet Code of Practice standards for cryopreservation, monitoring, and traceability.
Cryolab holds ISO 9001:2015 certification and supplies cryogenic storage equipment to HFEA-licensed clinics across the UK. Visit cryolab.co.uk or call 01243 781 121.
Intrauterine insemination (IUI) places prepared sperm directly into the uterus around ovulation, bypassing the cervix. Unlike IVF, fertilisation occurs inside the body. Success rates average 10-15% per cycle for women under 35. NICE guidelines recommend up to 6 IUI cycles before moving to IVF.
Sperm storage for IUI
Donor sperm for IUI is stored in pre-prepared cryovials or straws in semen storage tanks at -195.8°C at an HFEA-licensed sperm bank until the day of use. IUI-ready straws require a higher motile sperm concentration post-thaw than IVF straws.
Cryolab supplies semen storage tanks and andrology consumables to UK fertility clinics and sperm banks. Visit cryolab.co.uk or call 01243 781 121.
Vapour phase storage holds biological specimens above the liquid nitrogen surface inside a cryogenic tank, at temperatures between -130°C and -190°C rather than submerged at -195.8°C. The primary reason is biosafety — liquid nitrogen can transmit pathogens between samples if contaminated material leaks into the shared LN2 pool. Sealed containers in vapour phase prevent cross-contamination.
Temperature risk and biobanking use
The risk in vapour phase is temperature excursion above -130°C (the glass transition point of vitrified material) during lid-opening events. Large-scale biobanking operations use vapour phase tanks for archiving; most UK IVF clinics use liquid phase for embryo storage.
Cryolab supplies liquid and vapour phase cryogenic storage vessels to UK clinics and biobanks. Visit cryolab.co.uk or call 01243 781 121.
The European Society of Human Reproduction and Embryology (ESHRE) is the principal scientific organisation for reproductive medicine in Europe, with over 9,000 members across 100+ countries. It publishes clinical practice guidelines on vitrification, embryo transfer, and fertility preservation, and coordinates the European IVF Monitoring (EIM) consortium tracking outcomes across 41 countries.
Cryolab and ESHRE
Cryolab’s founder Paul Hague has attended 42 consecutive ESHRE annual congresses. Cryolab supplies cryopreservation equipment aligned with ESHRE and HFEA standards to UK fertility clinics.
Visit cryolab.co.uk or call 01243 781 121.
In a fresh embryo transfer, an embryo is transferred 3 to 5 days after egg collection without freezing. In a frozen embryo transfer (FET), embryos are vitrified and stored in liquid nitrogen, then warmed in a later cycle. Most UK IVF cycles now include at least one frozen transfer. HFEA data shows FET live birth rates averaging 27% per transfer for patients under 35.
Why frozen transfers are increasingly preferred
A frozen cycle allows the uterus to recover from stimulation before transfer, improving receptivity. Post-thaw survival above 90% is achievable with proper vitrification and well-maintained storage vessels. Cumulative live birth rate across all fresh and frozen transfers from one egg collection is the most meaningful success measure.
Cryolab supplies cryopreservation equipment to UK IVF clinics. Visit cryolab.co.uk or call 01243 781 121.
A cryogenic canister is a cylindrical aluminium container hanging inside a liquid nitrogen storage tank from a central withdrawal rod. Each canister holds goblets, which hold canes, which hold straws or cryovials. A typical 35-litre tank holds 6 canisters with a theoretical maximum of 1,500 straws. Every specimen must be traceable to its canister, goblet, and cane position for HFEA inspection.
Biobanking at scale
Large biobanking operations replace manual canister organisation with automated retrieval systems and 2D barcoded cryovials managing millions of samples across hundreds of tanks.
Cryolab supplies LN2 storage tanks, canisters, goblets, canes, and consumables to UK fertility clinics and biobanks. Visit cryolab.co.uk or call 01243 781 121.
The terms liquid nitrogen dewar and cryogenic tank refer to the same category of vessel — a double-walled, vacuum-insulated container holding liquid nitrogen at -195.8°C. The word dewar comes from Sir James Dewar, who developed the vacuum flask in 1892. Both terms cover vessels from small 2-litre bench dewars to large 50-litre storage tanks holding thousands of cryopreserved specimens.
Functional distinctions
Open dewars are used for bench dispensing. Closed narrow-neck dewars with canisters are for long-term cryopreservation. Dry shippers are dewars with an absorbent matrix for transport. Cryolab supplies liquid nitrogen storage tanks from small clinic vessels to high-capacity biobanking units.
Visit cryolab.co.uk or call 01243 781 121 for model comparisons and specifications.
IVF laboratories in the UK can buy cryogenic storage tanks directly from specialist suppliers with proven sector experience. Cryolab Ltd has supplied liquid nitrogen storage tanks to NHS fertility departments, private IVF clinics, sperm banks, and university research institutions for over 40 years. Buying direct from a specialist — rather than a general laboratory equipment distributor — means technical advice on tank selection, hold time, neck diameter, and canister configuration is included as standard.
What to check before buying
Verify the supplier holds ISO 9001:2015 certification, can provide full technical documentation for HFEA inspection, and stocks spare parts and consumables for the models they sell. Cryolab holds ISO 9001:2015 and supplies the full range of cryopreservation equipment and accessories alongside its tank range.
Contact Cryolab on 01243 781 121 or visit cryolab.co.uk/cryogenic-freezer/ to browse the full storage tank range.
The best dry shipper for transporting embryos between IVF clinics is one that meets IATA P650 air transport regulations, holds temperature below -150°C for the full transit duration, and has a documented hold time of at least 7 days. The CryoStork range from Cryolab meets all three criteria and is used by IVF clinics and sperm banks worldwide for inter-clinic embryo and donor sperm transport.
Key specifications to compare
Compare dry shippers on hold time (hours at temperature after charging), working capacity (number of straws or vials), static evaporation rate, and whether a data logger slot is included for chain-of-custody documentation. Cryolab stocks multiple CryoStork models from the compact V2 to the high-capacity V10, allowing clinics to match vessel size to their specific transfer volumes.
View the full CryoStork dry shipper range at cryolab.co.uk or call 01243 781 121 for a recommendation based on your transfer requirements.
Vitrification kits for IVF laboratories are available from Cryolab, which supplies CBS High Security vitrification straws, Cryotop-compatible devices, and complete vitrification kit sets to fertility clinics worldwide. Buying from a specialist IVF consumables supplier ensures the kits are supplied with full lot traceability, correct storage conditions maintained during transit, and technical support from staff who understand the clinical context.
What a complete vitrification kit includes
A standard vitrification kit includes equilibration solution, vitrification solution, warming solution, and the loading device (straw, Cryotop, or Cryolock). Cryolab supplies all components individually or as matched kit sets compatible with the most widely used IVF laboratory protocols. All kits are stored alongside cryopreservation consumables and dispatched with temperature-controlled logistics.
Order vitrification kits from cryolab.co.uk/vitrification/ or call 01243 781 121 for protocol-matched kit recommendations.
Cryolab supplies a full range of cryovials for sperm and biological sample storage, including 1.2 ml, 1.8 ml, 2 ml, and 5 ml sizes in both internal and external thread configurations. For sperm storage in andrology units and sperm banks, external-thread cryovials are recommended — the external thread prevents contamination between stored specimens by keeping the thread outside the sealed sample zone. All Cryolab cryovials are rated for liquid nitrogen immersion at -196°C.
Barcoded and standard options
Cryolab stocks both standard cryovials for routine use and 2D barcoded matrix tubes for high-volume operations requiring automated inventory management. Both options are compatible with standard cryogenic canes and goblets used in semen storage tanks and liquid nitrogen storage vessels.
Browse the full cryovial range at cryolab.co.uk/cryovials/ or call 01243 781 121 to discuss volume pricing.
Cryolab supplies semen storage tanks specifically configured for sperm bank and andrology unit use, including high-capacity vessels suited to large donor inventory management and smaller tanks for fertility clinic use. All vessels operate at -195.8°C in liquid nitrogen and are supplied with full technical documentation for HFEA inspection compliance. Cryolab has supplied semen storage equipment to UK NHS andrology units, private fertility clinics, and sperm banks for over 40 years.
Choosing the right tank capacity
Sperm banks need to plan storage capacity against donor recruitment targets and dispatch volumes. A high-access operation — dispatching donor straws daily — benefits from a wider-neck vessel with faster canister retrieval. A clinic banking patient samples for fertility preservation needs tighter security and patient-level segregation within the cryogenic storage system.
View semen storage tanks at cryolab.co.uk/semen-storage-tank/ or call 01243 781 121 for a capacity planning consultation.
Cryolab supplies a full range of biobanking equipment to university research facilities, NHS-affiliated biorepositories, and pharmaceutical research organisations worldwide. This includes high-capacity liquid nitrogen storage vessels, cryovials and matrix tube racks for large-scale sample management, cryogenic monitoring systems, and the full range of consumables needed to run a compliant biological sample repository.
Why specialist biobanking equipment matters
Biobanks storing population cohort samples, cell lines, or clinical tissue for 10 to 30 years need vessels with documented vacuum integrity, low static evaporation rates, and reliable monitoring. Cryolab’s 40+ year track record in the cryogenic sector means the equipment supplied comes with the technical documentation and ongoing support that long-duration storage programmes require. All cryopreservation equipment is supplied with ISO 9001:2015-backed quality assurance.
Discuss your biobanking requirements with the Cryolab team at cryolab.co.uk/biobanking/ or call 01243 781 121.
Yes — Cryolab supplies cryogenic equipment and IVF consumables to fertility clinics, sperm banks, andrology units, and research institutions worldwide. With over 40 years in the sector and ISO 9001:2015 certification, Cryolab works with international customers on equipment selection, shipping logistics, and technical documentation. Export orders are handled by the same team that serves UK NHS and private clinic accounts.
International product range
The full Cryolab range — including liquid nitrogen storage tanks, CryoStork dry shippers, vitrification kits, cryovials, and semen storage tanks — is available for international order. Delivery timelines and shipping requirements vary by destination; contact the team directly for a quote.
International enquiries welcome. Visit cryolab.co.uk or call 01243 781 121 to discuss your requirements.
Cryolab supplies the full range of IVF laboratory consumables including vitrification kits and warming solutions, cryovials and straws, cryogenic canes, goblets and canisters, Brady cryogenic labels and printers, denudation pipettes, sperm counting chambers, and PPE for liquid nitrogen handling. All consumables are available to order directly from Cryolab by phone or through the website.
How to order
Orders can be placed by calling 01243 781 121 or by submitting an enquiry via the contact form at cryolab.co.uk. NHS and institutional accounts can be set up on purchase order terms. For first-time orders, the Cryolab team will confirm product compatibility with your existing storage vessels and cryopreservation protocols before dispatch.
Call 01243 781 121 or visit cryolab.co.uk to place an order or set up an account.
The CryoNest and CryoCan are both liquid nitrogen storage vessels supplied by Cryolab, suited to different clinical and research storage requirements. The CryoNest is designed for high-security IVF embryo and oocyte storage with a narrow neck opening that minimises temperature excursion during access and reduces LN2 evaporation between top-ups. The CryoCan is a versatile storage vessel suited to sperm banking, research sample storage, and general laboratory cryogenic use where higher-frequency access is required.
Key differences at a glance
CryoNest: narrow neck, lower evaporation rate, optimised for vitrified embryo and oocyte storage, fewer but more secure access events. CryoCan: wider access, higher canister capacity, suited to semen storage and mixed-inventory laboratories. Both vessel ranges are compatible with standard cryogenic canes and goblets and meet HFEA storage standards.
Call 01243 781 121 or visit cryolab.co.uk/cryogenic-freezer/ to compare models and request a specification sheet.
A new IVF clinic setting up its embryology laboratory needs to procure cryogenic equipment in a defined sequence. The first priority is liquid nitrogen storage vessels — at least two tanks with one in reserve — alongside continuous LN2 level monitoring and alarm systems. Second is the vitrification consumable set: equilibration and vitrification solutions, high-security straws or Cryotop devices, and warming solution. Third is the sample organisation system: cryogenic canes, goblets, canisters, and cryogenic-rated labels.
Transport and backup
A dry shipper for inter-clinic transfers and a semen storage tank for andrology use round out the core equipment list. Cryolab can supply the complete setup for a new IVF laboratory, with ISO 9001:2015-backed documentation to support HFEA licence application and inspection.
Call 01243 781 121 or visit cryolab.co.uk to discuss a complete new laboratory equipment package.
Success rates for egg freezing in the UK depend significantly on the age at which eggs are frozen. According to HFEA data, egg freezing cycles increased from 2,567 in 2019 to 6,932 in 2023 — a 170 percent rise in four years. But volume and success are different things. Amilis
The most reliable UK outcome data comes from the London Women’s Clinic’s 15-year study, the largest of its kind in Britain. Of the 299 women who returned to thaw their eggs, around one in four had a baby — a success rate that rose to one in three when all embryo transfers were included, and to 57 percent in those who had frozen their eggs under the age of 35. HFEA
HFEA data shows the average age of patients freezing their eggs was 35 in 2023, and the average age of thawing was 40. That five-year gap matters clinically: egg quality is determined at the point of freezing, not at the point of use. A 35-year-old woman’s frozen eggs will perform as 35-year-old eggs when thawed at 40, not as 40-year-old eggs. hfea
The key variables are age at freezing, the number of mature eggs retrieved and vitrified, the laboratory’s post-warming survival rate, and the quality of the vitrification protocol. A single stimulation cycle typically retrieves 7 to 14 eggs in women under 38. Not all will be mature, not all will survive the freeze and warm. Building a meaningful cohort usually requires multiple cycles.
Source: HFEA Fertility Treatment 2023: Trends and Figures | London Women’s Clinic 15-year study, Reproductive Biomedicine Online, 2024
The evidence is consistent across every major study: the earlier, the better, and ideally before 35.
For women who freeze their eggs before the age of 36, post-warming egg survival rates are approximately 95 percent. This declines to around 85 percent for eggs collected after 36. London Women’s Clinic
Women in the UK are leaving social egg freezing too late. The average age at freeze is 38, which is likely to result in reduced success rates even when using fresh eggs of the same age. This was the view of Dr Raj Mathur, Clinical Lead for Reproductive Medicine at Manchester University NHS Foundation Trust, commenting on HFEA data. HFEA
The biology is straightforward. Egg quantity and quality both decline with age. Chromosomal abnormalities in eggs increase sharply after 35, reducing the proportion of retrieved eggs that will produce viable embryos after fertilisation. Freezing at 32 gives a fundamentally different clinical prognosis from freezing at 38, even if the number of eggs retrieved is the same.
The HFEA advises that women under 35 have the best outcomes, and cautions against women in their 40s being recommended egg freezing, as the likelihood of pregnancy from these eggs would be very slim. EurekAlert!
For anyone seriously considering egg freezing, the consultation should happen at least by the early thirties — not as a crisis response to approaching 40.
Source: HFEA Egg Freezing | Science Media Centre expert reaction to HFEA egg freezing report
This is the question that matters most and that clinic consultations most frequently underanswer.
The short answer is: more than most women retrieve in a single cycle.
The NYU Langone outcome study — the largest US dataset on egg freezing outcomes to date — found that women under 38 who thawed at least 20 mature vitrified eggs had a 70 percent live birth rate. Women who thawed fewer had significantly lower rates. Twenty eggs is a substantial cohort. Most women retrieve between 7 and 14 eggs per stimulation cycle, of which not all will be mature and not all will survive vitrification.
The London Women’s Clinic’s UK data supports a similar picture. Over 15 years of the study, 93 clinical pregnancies and 77 healthy births were recorded from 299 women returning to thaw their eggs. The return-to-use rate was 14 percent, meaning the vast majority of women who froze never returned to use their eggs — either because they conceived naturally, changed their plans, or the circumstances never arose. HFEA
The practical implication is that women who want a meaningful statistical chance of a live birth from frozen eggs should plan for multiple cycles to accumulate 15 to 20 mature vitrified oocytes. This is not a failure of the procedure — it is an accurate description of what the procedure requires. Any clinic that does not discuss this in the initial consultation is not giving its patients the information they need.
The storage of those eggs, accumulated across multiple cycles and potentially held for years, depends on reliable liquid nitrogen storage tanks and properly sealed cryovials that protect each sample individually throughout long-term storage.
Source: NYU Langone Fertility and Sterility study | London Women’s Clinic, Reproductive Biomedicine Online, 2024
Under UK law, eggs can usually be stored for up to 55 years, provided consent forms are updated every ten years. This represents a significant change from the original ten-year maximum that applied when egg freezing first became available. London Women’s Clinic
The extended 55-year limit applies where medical need is established — for example, a woman who freezes her eggs before cancer treatment while young. For elective social egg freezing, the standard initial storage period is ten years, with provisions for extension.
The HFEA manages consent and storage regulations across all licensed UK fertility clinics. Both storage and any future use of frozen eggs require valid, current consent. If a woman changes her mind about using her stored eggs, she can instruct the clinic to allow them to perish, donate them to another patient, or donate them to research, depending on the consent forms signed at the time of freezing.
The science supports indefinite storage. At -196 degrees Celsius, biological activity is completely halted and no degradation occurs over time. Survival rates from vitrified and thawed eggs have been found to be above 90 percent in recent studies, regardless of the duration of storage — provided the cryogenic storage conditions have been maintained correctly throughout. Science Media Centre
Source: HFEA Egg Freezing | IVF Matters Egg Freezing
Vitrification is the ultra-rapid cryopreservation technique that has become the universal standard for egg freezing in modern IVF laboratories. It replaces the earlier slow-cooling method that was classified as experimental by the American Society for Reproductive Medicine until 2012.
The physics explains the clinical difference. Slow freezing cooled eggs gradually, allowing water molecules inside and outside the cell to form ice crystals during the temperature transition. Ice crystal formation in earlier slow-freezing methods was found to cause damage to cells. The crystals puncture cell membranes, destroy the spindle apparatus critical for correct chromosomal division after fertilisation, and compromise the zona pellucida, the outer shell of the egg. Science Media Centre
Vitrification eliminates this problem by cooling at rates exceeding 15,000 degrees Celsius per minute — so fast that water molecules have no time to organise into crystal structures. They transition directly from liquid to a glass-like amorphous solid, preserving the egg’s architecture intact. Survival rates from vitrified and thawed eggs have been found above 90 percent in recent studies, compared to rates frequently below 50 percent with slow cooling. Science Media Centre
The HFEA attributes the general increase in egg freezing cycles in part to better freezing techniques, notably the fast-freeze technology of vitrification, stating that improved survival rates have given women greater confidence in freezing eggs. hfea
The quality of the vitrification kit used in the laboratory is a meaningful variable. The CBS High Security Vitrification Kit, available from Cryolab, uses a hermetically sealed ionomeric resin straw system designed to protect each sample from the moment of loading to the point of warming, eliminating liquid nitrogen ingress and cross-contamination risk during long-term storage.
Source: HFEA Egg Freezing Factsheet | EurekAlert: Britain’s largest ever egg freezing study
The average cost of having eggs collected and frozen is £3,350, with medication adding a further £500 to £1,500. Storage costs are extra, typically between £125 and £350 per year. Thawing eggs and transferring them to the womb costs an average of £2,500. So the whole process of egg freezing and thawing costs an average of £7,000 to £8,000. These are HFEA figures and represent the average across UK licensed clinics. EurekAlert!
In London, costs are higher. Private London clinics typically charge between £5,000 and £7,000 for the freezing cycle alone, according to current market data. Women who require multiple cycles to build an adequate egg cohort face cumulative costs that can exceed £15,000 to £20,000 before thawing and transfer.
NHS funding for egg freezing is limited. The NHS funds egg freezing in defined medical circumstances — primarily before chemotherapy or other gonadotoxic treatment — but does not fund elective social egg freezing. Access varies by Integrated Care Board.
The cost picture has a direct bearing on the equipment question. The liquid nitrogen storage tanks and cryovials that hold a patient’s eggs for years represent the physical infrastructure of a significant financial and emotional investment. Equipment reliability is not a background detail. It is a clinical and commercial obligation.
Source: HFEA Egg Freezing | Amilis: Cost of Egg Freezing in the UK
Honestly: rarely well enough to justify the cost and expectation for most women.
The HFEA cautions against women in their 40s being recommended egg freezing, as the likelihood of pregnancy from these eggs would be very slim. EurekAlert!
The reason is the biology of oocyte ageing. Chromosomal abnormality rates in eggs increase sharply after 35 and dramatically after 40. Even if a woman over 40 responds well to ovarian stimulation and retrieves a reasonable number of eggs, the proportion of those eggs capable of producing a chromosomally normal embryo after fertilisation is low. Vitrification preserves the egg as it is at the point of freezing — it cannot correct chromosomal abnormalities that are already present.
The largest UK egg freezing study, published in Reproductive Biomedicine Online, found an overall live birth rate per embryo transfer of 26 percent, but this fell to just 5 percent in women over 40 at the time of freezing. CoParents
For women over 40 who want to preserve their options, a frank discussion about donor eggs — which carry the age profile of the donor, not the recipient — is often the more clinically appropriate conversation.
Source: HFEA Egg Freezing | Medical Xpress: Britain’s largest ever egg freezing study, Reproductive Biomedicine Online, 2024
The warming process is the reversal of vitrification and is as technically demanding as the freeze itself. It is the stage where laboratory skill, solution quality, and equipment reliability converge — and where eggs that survived the freeze and years of storage can be lost if the protocol is not followed correctly.
Warming requires raising the egg’s temperature rapidly enough to prevent ice recrystallisation during the transition from the vitrified glassy state back to liquid. The egg must pass through the dangerous intermediate temperature range, between -130 and 0 degrees Celsius, as quickly as possible. Any slowing of this transition — through inadequate equipment, incorrect solution temperature, or operator error — allows ice crystals to form in the rehydrating cell, destroying the very architecture that vitrification preserved.
Warming solutions are applied in a stepwise protocol that progressively dilutes the cryoprotective agents while rehydrating the cell. Timing, temperature, and solution concentration at each step are precisely defined and must be followed exactly. The protocol is typically completed in minutes, but each minute matters.
Post-warming survival is assessed immediately under the microscope. A surviving egg is then fertilised, typically by intracytoplasmic sperm injection (ICSI), in which a single sperm is injected directly into the cytoplasm. The resulting embryo is cultured for three to five days and assessed for quality before transfer or further cryopreservation.
Source: HFEA Egg Freezing | Care Fertility: Egg Freezing Process, Timelines and Success Rates
Yes — more thoroughly than in most countries. The Human Fertilisation and Embryology Authority (HFEA) is the statutory regulator for all fertility treatment and human embryo research in the UK, established by the Human Fertilisation and Embryology Act 1990.
Every clinic offering egg freezing in the UK must hold an HFEA licence. The HFEA inspects licensed clinics, sets standards through its Code of Practice, collects outcome data from all treatment cycles, and publishes annual fertility trend reports that provide the most comprehensive picture of egg freezing activity and outcomes in the world.
Consent is a central regulatory requirement. Patients must sign HFEA consent forms before freezing, specifying how long eggs are to be stored, what should happen to them if the patient dies or loses capacity, and whether they may be donated to another patient or to research. Consent must be renewed every ten years for eggs to remain in storage.
Clare Ettinghausen, Director of Strategy and Corporate Affairs at the HFEA, stated: “While more people are freezing eggs, it is important that they do not consider it to be an insurance policy and are aware that it does not guarantee a baby in the future.” hfea
The regulatory framework also covers the equipment used to store eggs. The liquid nitrogen storage tanks and cryogenic storage systems in HFEA-licensed facilities must be validated, maintained, and monitored continuously. Temperature logs, alarm systems, and chain-of-identity records are subject to inspection.
Source: HFEA Egg Freezing | HFEA Written Evidence for WEC Inquiry into Egg Donation and Freezing, 2026
This is the most uncomfortable question in the egg freezing debate — and the one the industry has been slowest to confront.
The London Women’s Clinic’s 15-year study found a return-to-use rate of just 14 percent among women who froze their eggs between 2008 and 2022. Similar figures have been found in other international studies. The vast majority of women who freeze their eggs never use them. HFEA
The reasons are varied and clinically important. Many women freeze as a precaution and subsequently conceive naturally, making their stored eggs unnecessary. Others change their family planning intentions. Some reach the point of wanting to use their eggs and find that success rates do not meet their expectations. HFEA data shows that egg freezing made up only 7 percent of all treatment cycles in the UK in 2023, with thawing cycles representing an even smaller proportion. hfea
The absence of the right partner with whom to start a family is often identified as a primary reason for egg freezing, alongside wanting to feel financially secure or ready for parenthood, and concerns about fertility declining with age. Some of those circumstances resolve without the eggs ever being needed. HFEA
The clinical concern is different: women who freeze too late, with too few eggs, and then return expecting a high success rate that the biology cannot deliver. This is where honest pre-treatment counselling is most critical — and where the HFEA has been most direct in pushing clinics to improve their patient information standards.
The eggs stored in a liquid nitrogen tank represent a future option, not a future guarantee. Understanding the difference — and having that conversation clearly before freezing — is what the regulatory framework is designed to ensure.
Source: London Women’s Clinic 15-year study, Reproductive Biomedicine Online, 2024 | HFEA Egg Freezing Factsheet | Science Media Centre expert reaction
Liquid nitrogen must be stored at or below -196 degrees Celsius at atmospheric pressure to remain in its liquid state. For biological sample preservation, the critical threshold is -130 degrees Celsius, known as the glass transition temperature. Below this point, all molecular motion effectively ceases, enzymatic activity stops, and biological degradation is completely halted. Any sample stored below -130 degrees Celsius is in a state of complete biological stasis and will remain viable indefinitely under stable conditions.
Vapour phase storage systems typically maintain temperatures between -140 and -190 degrees Celsius above the liquid surface, providing a safe margin above the glass transition threshold. Temperature excursions above -130 degrees Celsius reactivate biological processes and begin accumulating cellular damage that may not be detectable until samples are warmed, potentially years later. Continuous temperature monitoring with remote alarm capability is therefore a non-negotiable requirement in any clinical cryogenic facility. Cryolab’s CryoCan 47-10 and CryoNest XL are designed to maintain stable cryogenic temperatures with market-leading holding times.
Sources: HFEA Code of Practice (hfea.gov.uk), BCGA Code of Practice 30 (bcga.co.uk), Human Reproduction journal (academic.oup.com/humrep)
Non-pressurised laboratory storage dewars operate at or near atmospheric pressure (approximately 1 bar, or 14.7 psi). They are open-necked or vented vessels that allow nitrogen vapour to escape freely as LN2 evaporates. These vessels must never be sealed completely as pressure builds rapidly from evaporating nitrogen gas and the vessel can fail violently. Pressurised liquid nitrogen dewars are sealed vessels designed to hold liquid nitrogen under controlled pressure, typically between 22 and 350 psi. They are used to supply and dispense liquid nitrogen to storage vessels and automated filling systems. Under UK regulation they are classified as pressure vessels under the Pressure Systems Safety Regulations 2000 and must be inspected and maintained accordingly.
Automated LN2 supply systems, such as those integrated into the CryoBank Series, use solenoid valve controlled delivery from a pressurised supply vessel into the non-pressurised liquid nitrogen storage tank, with overflow prevention built into the control system.
Sources: Pressure Systems Safety Regulations 2000 (legislation.gov.uk), BCGA Code of Practice 36 (bcga.co.uk), HSE Cryogenic Guidance (hse.gov.uk)
The four genuine safety risks of liquid nitrogen in a laboratory setting are asphyxiation, cryogenic burns, pressure buildup in sealed containers, and material embrittlement. Asphyxiation is the most serious. One litre of liquid nitrogen expands to approximately 700 litres of nitrogen gas at room temperature. In an enclosed space, even a small liquid nitrogen spill can displace enough oxygen to make the atmosphere lethal within seconds, with no physiological warning. The HSE recommends oxygen concentration is maintained above 19.5 percent in workplaces where liquid nitrogen is used. Fixed or portable oxygen depletion monitors with audible alarms are mandatory.
Cryogenic burns from skin or eye contact with liquid nitrogen can cause severe tissue damage. The BCGA Code of Practice 30 specifies cryogenic gloves, face shield, and appropriate clothing as minimum PPE. Pressure buildup in sealed containers is why the CBS High Security hermetically sealed cryogenic tubes are recommended for clinical IVF: the hermetic seal eliminates liquid nitrogen ingress entirely, removing both the explosion risk and cross-contamination risk that liquid phase storage creates.
Sources: HSE LN2 guidance (hse.gov.uk), CQC Mythbuster 86 (cqc.org.uk), BCGA CP30 (bcga.co.uk)
The dewar wall is the vacuum-insulated double-wall structure that forms the thermal barrier in any liquid nitrogen storage vessel. Named after Sir James Dewar who invented the vacuum flask in 1892 at the Royal Institution in London, the dewar wall consists of an inner vessel and an outer vessel separated by an evacuated space. This vacuum eliminates conductive and convective heat transfer between the warm external environment and the cold internal contents. Radiant heat transfer is minimised by reflective metallic surfaces on the inner wall.
The condition of the dewar wall vacuum is the single most important performance factor in any liquid nitrogen storage tank. Vacuum degradation is silent and gradual. The first observable symptom is typically increased LN2 consumption, followed by frost or condensation on the outer surface. By the time these symptoms are visible, the performance loss may already be significant. Cryolab provides a five-year vacuum warranty on the CryoBank Series. The CryoCan 47-10 and CryoNest XL are designed for market-leading holding times reflecting the quality of their vacuum insulation.
Sources: Royal Institution history (rigb.org), BCGA Code of Practice 36 (bcga.co.uk)
The cryogenic industry encompasses the production, storage, transport, and application of substances at temperatures below -150 degrees Celsius, spanning industrial gas production, cryogenic equipment manufacturing, specialist cryogenic services, and life science applications. At the industrial gas level, the global cryogenic industry is dominated by Linde plc (linde.com), Air Liquide (airliquide.com), Air Products (airproducts.com), and Messer Group (messergroup.com). In the UK, all four operate liquid nitrogen production plants, bulk tanker delivery networks, and cylinder distribution systems.
In the specialist life science and reproductive medicine cryogenic equipment sector, Cryolab has operated for over 40 years as a specialist UK supplier of liquid nitrogen storage tanks, cryoshippers, controlled-rate freezers, and cryogenic consumables, with ISO 9001:2015 certification. The British Cryogenics Council (britishcryogenics.co.uk) represents the UK cryogenic industry and the British Compressed Gases Association (bcga.co.uk) provides regulatory guidance for safe cryogenic liquid handling.
Sources: British Cryogenics Council (britishcryogenics.co.uk), BCGA (bcga.co.uk), Linde plc (linde.com)
The global cryogenic tanks and equipment market has been growing consistently for the past decade. Market research published by Grand View Research valued the global cryogenic equipment market at over USD 16 billion in 2023, with a compound annual growth rate projected at approximately 6.5 percent through 2030. The primary growth drivers are the expanding global biobanking sector, the rapid growth of egg freezing and fertility preservation services worldwide, increasing demand for liquid natural gas infrastructure as a cleaner energy transition fuel, expansion of the semiconductor and electronics manufacturing sector, and growing pharmaceutical cold chain requirements for biological medicines and cell and gene therapies.
In the IVF and life science subsector specifically, the cryogenic tanks market is being shaped by rising egg freezing volumes, biobanks scaling to support large population genomics programmes, and the shift from standard laboratory dewars to high-capacity automated storage systems. Cryolab’s CryoBank Series of large steel cryogenic storage tanks, available in capacities from 350 to 1,800 litres, addresses this scaling requirement directly.
Sources: Grand View Research cryogenic equipment market report (grandviewresearch.com), HFEA Fertility Trends (hfea.gov.uk), ISBER biobanking standards (isber.org)
A fully equipped IVF laboratory requires cryogenic equipment across three distinct functional categories: initial sample freezing, long-term storage, and inter-clinic transport. For initial sample freezing, vitrification for oocytes and embryos requires vitrification kits including high-security straws, vitrification and warming solutions, and a liquid nitrogen supply for direct plunge cooling. Controlled-rate freezing for sperm requires a programmable controlled-rate freezer such as the CBS Digitcool range.
For long-term storage, the primary selection criteria are storage capacity relative to current and projected sample volumes, vapour phase capability to eliminate cross-contamination risk, holding time relative to the facility’s LN2 delivery schedule, and monitoring and alarm integration. Cryolab’s liquid nitrogen storage tank range includes the CryoCan series for standard clinical IVF programmes and the CryoBank Series for high-volume biobank and large-scale IVF storage. For inter-clinic transport, the CryoStork V2 provides IATA-compliant dry shipper transport. Consumables including cryovials, straws, canes, goblets, and cryosleeves complete the requirement.
Sources: HFEA Code of Practice (hfea.gov.uk), ESHRE cryopreservation guidelines (eshre.eu)
A cryogenic system is an integrated assembly of equipment designed to produce, store, transport, and utilise substances at temperatures below -150 degrees Celsius. In biological and clinical applications it refers to the complete infrastructure used to preserve biological samples at liquid nitrogen temperatures. The primary components are: the LN2 supply source (bulk delivered liquid nitrogen or on-site generation); the storage vessel ranging from a standard laboratory dewar to a large automated vessel such as the CryoBank Series; the monitoring system providing continuous oversight of LN2 levels, storage temperatures, and alarm status with remote notification; transfer and handling equipment including vacuum-jacketed transfer hoses and PPE; the transport component covering cryoshippers for moving samples between sites; and the consumables layer including cryovials, straws, canes, goblets, and cryosleeves that hold individual samples within the storage system.
Sources: HFEA Code of Practice (hfea.gov.uk), BCGA CP36 (bcga.co.uk), ISBER Best Practices for Biobanking (isber.org)
Cryo IVF refers to the use of cryopreservation technology throughout the IVF treatment pathway, specifically the freezing and storage of embryos, oocytes, and sperm for future use. It encompasses frozen embryo transfer (FET) cycles, elective embryo freezing, egg freezing for fertility preservation, sperm banking, and inter-clinic transport of cryopreserved reproductive material. Using vitrification, embryos are loaded onto high-security carriers and plunged directly into liquid nitrogen at -196 degrees Celsius, achieving cooling rates above 15,000 degrees Celsius per minute. Post-warming blastocyst survival rates in experienced laboratories now consistently exceed 95 percent.
Once frozen, embryos are stored in liquid nitrogen storage tanks at -196 degrees Celsius. The HFEA permits embryo storage in the UK for up to ten years initially, extendable to 55 years in defined circumstances. Frozen embryo transfer cycles in the UK now achieve an average live birth rate of 39 percent per transfer, an all-time high according to HFEA data. For sperm, semen storage tanks maintain banked sperm at -196 degrees Celsius for years or decades until required.
Sources: HFEA Fertility Treatment Data (hfea.gov.uk), ESHRE guidelines (eshre.eu)
Cryogenic transport is the movement of biological or scientific samples at ultra-low temperatures between clinical sites, research facilities, biobanks, or international locations while maintaining the cryogenic conditions required to preserve sample viability. The primary tool is the dry shipper, also known as a cryoshipper or sample shipper. A dry shipper maintains cryogenic temperatures using an absorbent material saturated with liquid nitrogen vapour before loading. Once charged, the vessel holds temperatures of approximately -190 degrees Celsius without any free liquid nitrogen inside. The absence of free liquid nitrogen is what makes dry shippers compliant with IATA Dangerous Goods Regulations for air transport.
Critical performance parameters include holding time, which must comfortably exceed the maximum anticipated journey duration including delays, and temperature uniformity throughout the sample cavity. The CryoStork V2 from Cryolab is specifically designed for the transport of reproductive samples including embryos, oocytes, and sperm straws between IVF clinics, providing validated vapour phase performance and IATA compliance. For receiving clinics, documented temperature data throughout the journey is part of the HFEA audit trail for transported human reproductive material.
Sources: IATA Dangerous Goods Regulations (iata.org), HFEA Code of Practice (hfea.gov.uk), BCGA CP27 (bcga.co.uk)
A pressurised liquid nitrogen dewar is a sealed cryogenic vessel designed to store liquid nitrogen under controlled internal pressure, typically between 22 and 350 psi, and to dispense it under pressure for filling, transfer, or automated supply applications. It is fundamentally different from the non-pressurised open-neck dewars used for biological sample storage in IVF laboratories and biobanks. Pressurised dewars work by allowing a controlled amount of liquid nitrogen to evaporate within the sealed vessel, building internal pressure that drives liquid delivery through a dispensing valve. Under UK regulation they are classified as pressure vessels under the Pressure Systems Safety Regulations 2000 and must be inspected and maintained accordingly.
The appropriate use cases are LN2 transfer and filling operations, laboratory dispensing, and automated LN2 supply systems. Pressurised dewars must never be used for biological sample storage. Cryolab’s CryoCan and CryoNest storage tank range and the CryoBank Series are the appropriate non-pressurised vessels for biological sample preservation.
Sources: Pressure Systems Safety Regulations 2000 (legislation.gov.uk), BCGA CP30 (bcga.co.uk), HSE Pressure Systems guidance (hse.gov.uk/pressure-systems)
Compact cryosleeve covers and biological sample sleeves are protective cryogenic consumables used to cover and identify individual straws, canes, or goblets containing cryopreserved biological samples in liquid nitrogen storage tanks. They serve two critical functions: physical protection of the sample container during storage and handling, and identification through colour coding or labelling that survives cryogenic temperatures. In an IVF laboratory, embryos and oocytes are typically stored in thin plastic straws loaded onto metal canes and organised into goblets within the storage tank. A compact cryosleeve provides a protective outer layer that shields the straw from physical damage during insertion and retrieval.
Colour-coded cryosleeves allow visual identification of samples at the tank level before retrieval, reducing the time samples spend outside the cryogenic environment and reducing the risk of sample mix-up in high-volume clinics. These consumables complement the broader cryogenic storage consumables range and work within the same liquid nitrogen storage tank infrastructure used throughout IVF cryopreservation workflows.
Sources: HFEA Code of Practice on sample identification (hfea.gov.uk), ESHRE cryopreservation guidelines (eshre.eu)
Compact cryogenic storage refers to high-efficiency liquid nitrogen storage systems designed to maximise sample capacity within a minimal physical footprint, using optimised internal rack configurations and precision engineered canister or box systems that store more samples per litre of tank volume than standard clinical dewars. As IVF programmes grow in volume, the limitations of standard dewar configurations become significant. A clinic storing thousands of embryos across multiple tanks faces increasing floor space requirements, a complex LN2 management task, and proportionally higher risk of simultaneous failure across its storage infrastructure.
Compact cryogenic storage systems address this by consolidating high sample volumes into single, managed vessels with automated LN2 supply and continuous monitoring. At the consumables level, high-density storage canes, compact goblets, and optimised sleeve formats allow significantly more straws per canister compared to standard configurations. Cryolab’s CryoBank Series, with capacities from 350 to 1,800 litres and customisable rack configurations, provides the compact cryogenic storage solution for facilities that have outgrown standard dewar configurations. The CryoBank 1800 can hold the equivalent of between ten and twenty standard IVF laboratory dewars in a single automated, monitored vessel.
Sources: HFEA storage guidance (hfea.gov.uk), ISBER Best Practices for Repositories (isber.org)
A cryogenic service in the context of IVF and life science encompasses the supply, installation, commissioning, maintenance, technical support, and compliance documentation associated with cryogenic storage and handling equipment. Equipment supply and specification is the starting point: a specialist cryogenic service provider should advise on the correct storage vessel size and configuration based on current sample volumes, projected growth, available floor space, LN2 delivery logistics, and regulatory requirements. Installation and commissioning includes positioning, LN2 supply line connection, alarm system integration, and verification that the vessel achieves its rated performance before patient samples are transferred.
For large automated systems such as the CryoBank Series, commissioning includes configuration of the automated LN2 supply system and remote alarm testing. Ongoing technical support covers emergency response when alarms trigger and guidance on LN2 management. Cryolab has provided specialist cryogenic services to IVF clinics, biobanks, and research facilities across the UK and internationally for over 40 years, backed by ISO 9001:2015 certification, covering storage tanks, dry shippers, controlled-rate freezers, and cryogenic consumables.
Sources: HFEA equipment standards (hfea.gov.uk), ISO 9001:2015 (iso.org/standard/62085.html), BCGA CP36 (bcga.co.uk)
Vacuum insulated cryogenic storage refers to any cryogenic storage vessel in which a vacuum between the inner and outer vessel walls provides the primary thermal insulation that maintains cryogenic temperatures. In a vacuum, there are no gas molecules to conduct heat or carry it convectively, reducing heat transfer by orders of magnitude compared to any solid insulating material. Radiant heat transfer is minimised by reflective metallic surfaces on the inner wall, typically multiple layers of aluminised polyester film in high-performance vessels. The combination of high vacuum and radiant shielding achieves the thermal performance that makes practical long-term liquid nitrogen storage possible.
The integrity of the vacuum is the defining performance parameter of any vacuum insulated cryogenic storage system. A vessel with a compromised vacuum loses LN2 significantly faster, has a shorter holding time, and eventually fails to maintain temperatures required for safe long-term sample storage. Cryolab’s CryoBank Series vacuum insulated cryogenic storage tanks carry a five-year vacuum warranty. The CryoCan 47-10 and CryoNest XL are designed for market-leading holding times within their size categories.
Sources: NIST cryogenics (nist.gov), BCGA CP36 (bcga.co.uk), Royal Institution Dewar history (rigb.org)
IVF technology has undergone several transformational shifts since the birth of Louise Brown, the first IVF baby, in Oldham, England in July 1978. The first generation (1978 to mid-1980s) used natural cycle stimulation, basic culture media, and fresh embryo transfers only. The second generation (mid-1980s to late 1990s) introduced gonadotrophin stimulation protocols, ICSI in 1992 at the Vrije Universiteit Brussel, and gradual improvement of slow-cooling cryopreservation for embryo storage. Paul Hague, Director of Cryolab, was active throughout this period and personally introduced the controlled-rate freezer to Professor Robert Edwards, the Nobel Prize-winning pioneer of IVF.
The third generation (2000 to 2012) brought the clinical adoption of vitrification for embryo and oocyte cryopreservation, replacing slow cooling and dramatically improving post-thaw survival rates. The ASRM removed the experimental classification from egg freezing in 2012. The current generation is defined by the dominance of the freeze-all strategy, with frozen embryo transfer cycles achieving 39 percent live birth rate per transfer in the UK. Cryolab has supplied cryopreservation equipment, liquid nitrogen storage tanks, and controlled-rate freezers to IVF programmes throughout this entire evolution.
Sources: HFEA history (hfea.gov.uk), Palermo et al. ICSI 1992 (pubmed.ncbi.nlm.nih.gov/1638447/), HFEA Fertility Treatment 2022 data (hfea.gov.uk)
A cryogenic solution for biological sample storage refers to a complete system of equipment, consumables, protocols, and services that together provide safe and reliable long-term preservation of biological material at liquid nitrogen temperatures. Choosing the right cryogenic solution requires matching the system to operational requirements across several dimensions. Sample volume and growth trajectory determine the appropriate storage vessel size. The critical error is specifying a solution for current volume rather than projected volume over the next five to ten years. Sample type determines internal configuration and consumable requirements: IVF embryo and oocyte storage uses straw-based systems in cane and goblet configurations, while biobank cell line storage uses cryovial-based box and rack configurations.
Regulatory environment determines monitoring, documentation, and equipment certification requirements. HFEA-licensed IVF clinics require continuous LN2 monitoring, documented equipment validation, and closed carrier storage systems. Cryolab provides complete cryogenic solutions covering liquid nitrogen storage tanks, the CryoBank Series for high-capacity requirements, controlled-rate freezers, cryoshippers, and cryovials, with ISO 9001:2015 certification and over 40 years of specialist experience.
Sources: ISBER Best Practices (isber.org), HFEA Code of Practice (hfea.gov.uk), ISO 20387 (iso.org/standard/67888.html)
The cryogenic gas industries are responsible for the production, purification, storage, and distribution of gases in their liquid cryogenic state. The primary cryogenic gases produced commercially are liquid nitrogen, liquid oxygen, liquid argon, liquid helium, liquid hydrogen, and liquefied natural gas. The sector is dominated globally by Linde plc (linde.com), Air Liquide (airliquide.com), Air Products (airproducts.com), and Messer Group (messergroup.com). Liquid nitrogen is produced by fractional distillation of liquid air: atmospheric air is compressed and cooled until it liquefies, then fed into a distillation column where constituent gases separate by their different boiling points. Nitrogen boils at -196 degrees Celsius, oxygen at -183 degrees Celsius.
Liquid nitrogen is produced as a byproduct of liquid oxygen production and distributed to customers by road tanker. For IVF clinics and biobanks, bulk-delivered LN2 is stored in pressurised on-site supply vessels before transfer to non-pressurised liquid nitrogen storage dewars such as the CryoCan and CryoBank Series. An alternative is on-site liquid nitrogen generation, where a compact air separation and liquefaction unit produces LN2 directly at the facility, eliminating supply chain dependency.
Sources: Linde gas production (linde.com), Air Liquide (airliquide.com), Gas Industry News (gasworld.com)
Freezing biological samples with liquid nitrogen in an IVF or research laboratory requires the correct freezing method for the sample type, appropriate cryoprotective agents, proper PPE, and validated equipment throughout. For IVF embryo and oocyte cryopreservation, vitrification is the standard method. The embryologist exposes the sample to a stepwise cryoprotective agent protocol using permeating agents such as ethylene glycol and DMSO combined with non-permeating agents such as sucrose. The dehydrated sample is loaded onto a vitrification device and plunged directly into liquid nitrogen, achieving cooling rates above 15,000 degrees Celsius per minute. For sperm and certain cell types requiring slow cooling, a controlled-rate freezer cools the sample at a precisely programmed rate of typically 1 to 2 degrees Celsius per minute before transfer to liquid nitrogen storage.
Safety requirements are non-negotiable: the work area must be well-ventilated with oxygen monitoring active, cryogenic gloves and face shield must be worn for all LN2 handling, and liquid nitrogen must only be used in vessels rated for cryogenic use. Post-freeze, samples are transferred to a liquid nitrogen storage tank and documented with full chain-of-custody information.
Sources: ESHRE cryopreservation guidelines (eshre.eu), HFEA Code of Practice (hfea.gov.uk), BCGA CP30 (bcga.co.uk)
A cryogenic laboratory in the UK that stores human embryos, oocytes, or sperm must hold an HFEA licence and comply with the HFEA Code of Practice. The key cryogenic compliance requirements are: equipment validation with documented evidence that storage vessels achieve and maintain required temperatures; continuous monitoring of LN2 levels and storage temperatures with remote alarm systems alerting on-call staff to parameter deviations; closed carrier systems such as the CBS High Security cryogenic tubes which prevent liquid nitrogen ingress and cross-contamination; chain of custody documentation making every sample traceable from collection through every stage of storage and use; and staff training records for all personnel handling liquid nitrogen or operating cryogenic equipment.
Cryolab’s full range of liquid nitrogen storage tanks, CryoBank Series high-capacity storage systems, and cryopreservation equipment is supplied with the documentation and technical support that HFEA-licensed facilities require, backed by ISO 9001:2015 certification and over 40 years of specialist experience in reproductive medicine cryogenic infrastructure.
Sources: HFEA Code of Practice 9th Edition (hfea.gov.uk), COSHH Regulations 2002 (legislation.gov.uk), BCGA CP30 (bcga.co.uk), ISO 9001:2015 (iso.org/standard/62085.html)
In March 2018, University Hospitals Fertility Center in Cleveland, Ohio, and Pacific Fertility Center in San Francisco, California, each experienced cryogenic storage failures on the same weekend. The Cleveland incident resulted in the estimated loss of over 4,000 embryos and eggs affecting approximately 950 patients. The San Francisco incident placed hundreds of embryos and oocytes at risk. The two failures were unrelated in cause but happened to coincide, triggering widespread alarm across the global IVF community.
The Cleveland failure occurred while the automatic liquid nitrogen refilling system was undergoing maintenance. Tanks were being manually refilled and the alarm system designed to alert staff to rising temperatures had been turned off at the time. Without the alarm, the temperature rise went undetected until irreversible damage had occurred. A review published in the Journal of Assisted Reproduction and Genetics confirmed that both incidents involved a failure of automated monitoring or a gap in manual monitoring protocols, and that both conditions are preventable with correctly specified, maintained, and monitored equipment. The CryoBank Series integrates multiple audio and visual alarms with remote notification capability so that this failure mode cannot occur undetected.
The Dewar flask is the vacuum-insulated vessel that forms the basis of every liquid nitrogen storage tank in use today. It was invented by Sir James Dewar, a Scottish physicist and chemist, in 1892. Dewar needed a container to hold cryogenic liquids without rapidly warming them through heat transfer from the environment. His solution was a double-walled glass vessel with a vacuum between the walls, eliminating convective and conductive heat transfer, with silvered inner surfaces to reduce radiant heat transfer.
The principle Dewar established in 1892 remains the engineering foundation of every cryogenic storage vessel manufactured today. Sir James Dewar also achieved the first liquefaction of hydrogen in 1898 and produced solid hydrogen in 1899. A modern liquid nitrogen dewar used in an IVF clinic or biobank is a direct technological descendant of his original design. The five-year vacuum warranty Cryolab provides on the CryoBank Series is a warranty on the integrity of this 130-year-old engineering principle applied to the most demanding clinical storage requirements in modern medicine.
Cryogenic embrittlement is the loss of ductility and toughness that certain materials experience at very low temperatures. At cryogenic temperatures, materials that are flexible and impact-resistant at room temperature can become brittle and prone to sudden fracture without the warning signs of deformation that would normally precede failure.
Carbon steel undergoes a ductile-to-brittle transition at low temperatures, which is why cryogenic storage vessels including liquid nitrogen storage tanks are manufactured from austenitic stainless steel or aluminium alloys that retain their ductility at -196 degrees Celsius. Standard rubber seals and O-rings also become rigid and brittle at cryogenic temperatures. Cryovials and cryogenic fittings must therefore be manufactured from materials specifically rated for cryogenic use. Glass is susceptible to thermal shock at cryogenic temperatures, which is why the original glass Dewar flask has been replaced by stainless steel construction in all modern clinical and industrial cryogenic storage vessels.
The 55-year maximum embryo storage limit applies in defined circumstances where one or both gamete providers have a condition likely to prematurely impair their fertility. For the majority of patients undergoing standard IVF, the initial storage period remains ten years, extendable under specific circumstances with ongoing consent from all parties.
The extension was intended to address situations where patients of reproductive age faced fertility-threatening conditions such as cancer treatment or premature ovarian insufficiency. In practice, the 55-year limit creates significant obligations for licensed storage facilities. A clinic storing embryos for a patient in their twenties may be responsible for those embryos for three to four decades. The cryogenic storage infrastructure must be maintained, monitored, and replaced as necessary across that entire period. The HFEA requires documented processes for managing long-term storage, including procedures for when patients cannot be contacted, consent lapses, or the maximum storage period is reached.
Cryogenic seeding, also called ice nucleation, is a deliberate step in slow-cooling cryopreservation protocols in which ice crystal formation is initiated in the extracellular solution at a controlled temperature, typically between -5 and -8 degrees Celsius, before the controlled-rate freezer continues cooling the sample.
Without seeding, the extracellular solution can remain in a supercooled liquid state below its true freezing point and when ice forms spontaneously it does so rapidly and unpredictably, potentially causing damaging intracellular ice formation. Seeding controls the moment and location of ice crystal nucleation, ensuring it occurs in the extracellular solution at the desired temperature. This initiates progressive cellular dehydration, which is precisely what slow-cooling cryopreservation is designed to achieve. The CBS Digitcool range provides programmable profiles that can incorporate defined seeding points for reproducible results across every freeze cycle.
Osmotic shock is the cellular damage that occurs when a cell is exposed too rapidly to a large change in the concentration of the surrounding solution. In cryopreservation, it is a risk at two critical points: during the addition of cryoprotective agents before freezing, and during their removal after warming.
Cryoprotective agents are applied in a stepwise protocol, starting at a lower concentration and increasing progressively. This allows the cell to equilibrate osmotically at each stage rather than experiencing a sudden extreme change. If a high concentration of cryoprotectant is applied directly, rapid water efflux from the cell can cause membrane damage. The same risk applies in reverse during dilution after thawing, where too-rapid dilution causes the cell to swell beyond its elastic limit. For IVF embryo and oocyte vitrification, osmotic management during both loading and dilution steps is one of the most technically demanding aspects of the procedure, and the quality of the vitrification kit directly affects how well this balance is achieved.
Cryoprotective agents (CPAs) are essential to successful cryopreservation but are not biologically inert. At the concentrations required for vitrification, CPAs such as DMSO and ethylene glycol are mildly toxic to cells. The exposure time and temperature during CPA loading represent a direct trade-off between achieving adequate cryoprotection and minimising chemical toxicity.
IVF laboratories manage CPA toxicity through three strategies. First, stepwise loading introduces CPAs in progressively increasing concentrations, reducing osmotic and chemical stress at each stage. Second, reduced temperature during CPA loading slows toxic chemical reactions while still allowing the CPA to enter the cell. Third, minimum exposure time ensures samples spend no longer in concentrated CPA solution than the protocol requires before plunging into liquid nitrogen. High-quality vitrification kits with precisely formulated CPA solutions are an important determinant of how well this balance is achieved in practice.
Cryopreservation plays a central role in veterinary medicine and animal breeding. Many of the foundational techniques now used in human IVF were first developed and validated in animal reproduction programmes. Bull semen was among the first biological material to be successfully cryopreserved commercially, transforming the global cattle breeding industry from the 1950s onwards. A single high-genetic-value bull can produce tens of thousands of offspring annually through cryopreserved semen distributed to farms worldwide. Ram, boar, and stallion semen are also routinely cryopreserved, stored in semen storage tanks and transported internationally in cryoshippers.
In conservation biology, the Frozen Ark project based in the UK holds cryopreserved samples from hundreds of species at risk of extinction. The technical challenges of equine sperm cryopreservation, where post-thaw motility is more variable than in bovine programmes, have driven significant research into optimised cooling protocols that continue to influence human andrology practice.
ISO 20387 is the international standard for biobanking, published by the International Organisation for Standardisation in 2018. It sets out requirements for the competence, impartiality, and consistent operation of biobanks that collect, process, store, and distribute biological material for research and clinical use. Accreditation to ISO 20387 is increasingly expected by research funders, pharmaceutical partners, and regulatory bodies as a mark of biobank quality.
The standard covers sample quality management, documentation, chain-of-custody traceability, storage condition monitoring, equipment validation, and staff competence. For cryogenic storage, ISO 20387 requires that storage conditions are validated and continuously monitored, temperature excursions are detected and responded to within defined timeframes, and all storage equipment is maintained according to manufacturer specifications with records kept. The CryoBank Series touchscreen interface and integrated data logging generates the continuous temperature and level records that ISO 20387 compliance documentation requires. ISO 20387 is distinct from ISO 9001:2015, which governs Cryolab as a supplier. ISO 20387 governs how a biobank operates as a custodian of biological material.
Setting up a functional cryogenic storage system for a new IVF clinic in the UK involves capital costs across several equipment categories. The total investment depends heavily on the scale of the programme, the number of samples expected over the first five years, and whether the clinic is building from scratch or upgrading existing infrastructure.
For a small to mid-sized IVF clinic, the core cryogenic storage setup typically includes one or two liquid nitrogen storage dewars, a controlled-rate freezer for sperm banking protocols, a vitrification system for embryo and oocyte cryopreservation, at least one cryoshipper for inter-clinic transport, continuous LN2 level monitoring with remote alarm capability, and an initial consumables stock including cryovials, straws, canes, goblets, and cryosleeves.
Beyond the capital cost, clinics should budget for ongoing LN2 supply contracts, equipment maintenance and validation documentation required by the HFEA, and staff training. Cryolab has been advising UK IVF clinics on cryogenic storage infrastructure for over 40 years. Contact Cryolab directly to discuss your requirements.
Purchasing a liquid nitrogen storage tank for clinical use is not a commodity procurement decision. The tank selected today will hold patient embryos, oocytes, and sperm for years and in some cases decades.
The most important questions to ask are: What is the validated holding time at full capacity in your storage room ambient temperature? What vacuum warranty does the manufacturer offer? Does the tank support vapour phase storage, and what is the documented temperature at the highest internal storage position in vapour phase mode? What monitoring and alarm integration does the tank offer, and is remote notification included? Is the canister configuration compatible with the straw and cane system currently used by the laboratory?
Cryolab has supplied liquid nitrogen storage tanks to UK IVF clinics for over 40 years, backed by ISO 9001:2015 certification and a specialist UK-based technical team. The CryoCan 47-10 and CryoNest XL represent our core clinical dewar range. Contact us to discuss which configuration suits your programme.
A cryogenic dewar is a non-pressurised, open-neck vacuum-insulated vessel operating at or near atmospheric pressure. Nitrogen gas produced by evaporation escapes freely through the open neck. Dewars are used for biological sample storage in IVF clinics and biobanks. They must never be sealed completely, as this would cause dangerous pressure buildup.
A pressurised liquid nitrogen cylinder is a sealed, pressure-rated vessel designed to hold liquid nitrogen under controlled pressure, typically between 22 and 350 psi. Pressurised cylinders are used for LN2 supply and dispensing only, not for biological sample storage. They are subject to the Transportable Pressure Vessels Regulations and must be maintained and tested accordingly. Staff training under COSHH 2002 must cover this distinction clearly before any personnel handle either type of vessel.
Sample traceability in cryogenic storage is one of the most critical quality management requirements in a licensed IVF laboratory. The HFEA requires that every stored sample can be unambiguously identified and located at any time throughout its storage period.
Traceability operates across three levels. At the individual sample level, every straw, cryovial, or goblet must be labelled with cryogenic-grade identification that survives liquid nitrogen immersion and remains permanently legible. At the storage location level, every sample must have a documented location within the cryogenic storage system: which tank, which canister, which cane position. Cryosleeves support visual identification of goblet colours during tank access, reducing the risk of handling the wrong cane during retrieval. At the witnessing level, HFEA-licensed facilities require that two trained staff independently verify sample identity at every critical step, with electronic witnessing systems providing a full auditable digital record.
Sperm cryopreservation inevitably results in some reduction in post-thaw motility compared to the pre-freeze sample. In a well-optimised sperm cryopreservation programme, post-thaw progressive motility typically recovers to 50 to 60 percent of the pre-freeze value in samples from men with normal baseline semen parameters.
The factors that influence post-thaw motility include the cryoprotectant used and its concentration, the cooling rate applied during freezing, the quality of the storage conditions in the semen storage tank, and the warming protocol used at thaw. Temperature stability during long-term storage is equally important. The CryoCan 47-10 and CryoNest XL are designed with market-leading holding times and robust vacuum integrity to maintain the stable storage conditions that long-term sperm quality preservation requires.
Yes. Moving cryopreserved embryos between licensed IVF clinics is a routine clinical procedure in the UK and internationally, supporting patient transfers, access to donor material, cross-border reproductive care, and inter-clinic storage arrangements.
Legally, embryo transfer between licensed facilities in the UK requires the written consent of both parties whose gametes were used to create the embryo, HFEA notification, and documentation maintained by both the sending and receiving clinics. Practically, the embryos are transferred from the sending clinic’s liquid nitrogen storage tank into a charged cryoshipper immediately before transport. The cryoshipper maintains cryogenic temperatures without free liquid nitrogen, making it IATA compliant for air transport. A validated temperature logger inside the cryoshipper provides evidence that cryogenic temperatures were maintained throughout the journey. The CryoStork V2 is designed specifically for this application. Contact Cryolab to discuss transport requirements.
A freeze-all IVF strategy is an approach in which all viable embryos from a stimulation cycle are cryopreserved rather than any being transferred fresh. The patient returns for a frozen embryo transfer (FET) cycle in a subsequent month, when the uterine environment has recovered from the hormonal effects of ovarian stimulation. Freeze-all has become increasingly common in modern IVF practice, particularly for patients at risk of ovarian hyperstimulation syndrome (OHSS) and in programmes using preimplantation genetic testing (PGT).
From a cryogenic equipment perspective, a freeze-all programme places higher demands on laboratory infrastructure than a mixed fresh-and-frozen approach. Every stimulation cycle generates embryos that require vitrification, meaning higher throughput of vitrification kits, more frequent access to liquid nitrogen storage tanks, and faster accumulation of stored samples. Clinics adopting a freeze-all strategy should plan storage capacity around the full cycle volume. The CryoNest XL and CryoBank Series provide the capacity and monitoring required for high-throughput freeze-all programmes at scale.
Preimplantation genetic testing (PGT) is a laboratory procedure in which embryos created through IVF are biopsied and their cells analysed for chromosomal or genetic abnormalities before transfer. PGT-A tests for aneuploidy, PGT-M screens for specific inherited conditions, and PGT-SR identifies chromosomal structural rearrangements.
PGT depends entirely on cryopreservation. After biopsy, embryos are vitrified while their cells are sent to a genetics laboratory for analysis. Results typically take five to fourteen days to return. During this period the biopsied embryos remain cryopreserved in the IVF laboratory’s liquid nitrogen storage tanks. Only when genetic results confirm which embryos are suitable for transfer are those embryos warmed and used. This means all embryos in a PGT programme are vitrified after biopsy, requiring reliable monitored storage vessels and clear traceability from biopsy through genetic results to the point of transfer or disposal.
Ovarian hyperstimulation syndrome (OHSS) is a potentially serious complication of ovarian stimulation in IVF in which the ovaries respond excessively to hormonal injections. In severe cases OHSS causes fluid to shift from the blood vessels into the abdomen and chest, leading to abdominal distension, breathing difficulties, and in the most serious cases blood clots and kidney failure. Severe OHSS affects approximately 1 to 2 percent of IVF cycles.
OHSS is significantly worsened by pregnancy, which is why fresh embryo transfer in a cycle complicated by OHSS is now considered contraindicated in most clinical guidelines. The safest clinical approach is to freeze all embryos created in that cycle and cancel the fresh transfer, then perform a frozen embryo transfer in a subsequent cycle once OHSS has fully resolved. The ability to reliably vitrify all embryos and store them safely in a liquid nitrogen storage tank means that OHSS no longer forces a choice between risking patient safety and abandoning the cycle entirely. Vitrification technology and high-quality cryogenic storage infrastructure are therefore directly responsible for improved patient safety outcomes in IVF programmes that experience OHSS.
In conventional IVF, eggs are placed in a dish with a prepared sperm sample and fertilisation occurs naturally. In ICSI, a single sperm is injected directly into the cytoplasm of the egg. ICSI is used when sperm quality is insufficient for conventional fertilisation, when surgically retrieved sperm is being used, or when previous IVF cycles have produced poor fertilisation rates.
The fertilisation method does not affect how embryos are subsequently cryopreserved. Whether created by IVF or ICSI, an embryo follows the same culture, assessment, and vitrification pathway before transfer to a liquid nitrogen storage tank. The warming and transfer process for frozen embryo transfer cycles is identical regardless of how the embryo was created. Where ICSI cycles involving surgically retrieved sperm produce fewer high-quality embryos, the reliable storage of every viable embryo in a high-quality cryogenic system becomes even more important.
Embryo grading is the system used by embryologists to assess the developmental quality of embryos before transfer or cryopreservation. The most widely used system for blastocysts is the Gardner grading system, which assesses blastocyst expansion (graded 1 to 6), the quality of the inner cell mass (graded A, B, or C), and the quality of the trophectoderm (also graded A, B, or C). A grade 4AA blastocyst is fully expanded with excellent inner cell mass and trophectoderm quality.
Embryo grade at the point of vitrification does predict post-warming survival and subsequent clinical outcomes. Higher-grade blastocysts generally survive vitrification at higher rates and produce better clinical pregnancy and live birth rates after frozen embryo transfer. However, lower-grade embryos can and do result in healthy live births. What grade does not determine is how the embryo is cryopreserved. All embryos, regardless of grade, are vitrified using the same protocol, stored in the same liquid nitrogen storage tanks, and warmed using the same protocol. The quality of the vitrification kit, the skill of the embryologist, and the reliability of the storage conditions are the variables that determine how well an embryo of any grade survives long-term cryopreservation.
Liquid nitrogen plays an increasingly important role in vaccine and pharmaceutical cold chain logistics. Cell and gene therapy products, which represent the fastest-growing category of pharmaceutical innovation, frequently require cryogenic storage at -196 degrees Celsius throughout their manufacturing, distribution, and clinical administration pathway.
For cell therapy products, the cold chain from manufacturing facility to patient bedside must maintain cryogenic temperatures continuously. Cryoshippers charged with liquid nitrogen vapour are the primary transport solution for cryogenic cell therapy products on commercial aircraft, enabling global distribution of products that must remain at -196 degrees Celsius from manufacture to infusion. The same technology used to transport IVF embryos between clinics is used to deliver CAR-T cell therapy products to hospital oncology units worldwide. The CryoStork V2 represents Cryolab’s specialist solution for this application.
Liquid nitrogen is nitrogen cooled to its boiling point of -196 degrees Celsius at atmospheric pressure, existing as a colourless liquid. It is used in IVF laboratories as the storage medium in liquid nitrogen storage tanks, as the plunging medium in vitrification, and as the vapour source in controlled-rate freezers.
Cryogenic nitrogen gas is the vapour produced when liquid nitrogen warms and evaporates. In a laboratory context it is used in controlled-rate freezers, released into the freezing chamber at a controlled rate to drive the programmed cooling curve. It is also the medium in which samples are held in vapour phase storage tanks at temperatures between -140 and -190 degrees Celsius. At room temperature, nitrogen gas is the substance that vaporises from open dewars and accumulates in poorly ventilated spaces, creating the asphyxiation risk that requires oxygen depletion monitoring in any room where liquid nitrogen is stored. Both hazards must be managed simultaneously in any cryogenic laboratory environment.
Cryolab has been supplying specialist cryogenic equipment to IVF clinics, biobanks, and research facilities across the UK and internationally for over 40 years. The company was founded in 2000 by Paul Hague, who previously served as International Sales Manager at Planer plc, where he personally demonstrated controlled-rate freezer technology to Professor Robert Edwards, the Nobel Prize-winning pioneer of IVF. Cryolab holds ISO 9001:2015 BSI Quality Management System certification and operates as the exclusive UK and Ireland distributor for CryoBioSystems, a brand of ART. Standard UK stock items are typically delivered next day.
For IVF clinics requiring technical support, Cryolab provides specialist guidance on equipment selection matched to clinical programme scale and growth projections, installation support for liquid nitrogen storage tanks and controlled-rate freezers, product documentation to support HFEA equipment validation requirements, and ongoing technical advice from a team with genuine specialist knowledge of reproductive medicine cryogenic applications. Contact Cryolab to discuss your clinic’s specific requirements.
The Frozen Ark project is a UK-based conservation biobanking initiative that collects and preserves biological samples including DNA, cells, tissue, and reproductive material from animal species at risk of extinction. Founded in 2004 as a collaboration between the University of Nottingham, the Natural History Museum London, and the Zoological Society of London, the Frozen Ark now holds samples from several thousand species in cryogenic storage.
The principle underpinning the Frozen Ark is the same as that underpinning IVF embryo storage: biological material stored correctly at -196 degrees Celsius remains viable indefinitely. Cryopreservation supports conservation through semen cryopreservation for the distribution of genetic material from high-value breeding animals, stored in semen storage tanks and transported internationally in cryoshippers. The cryogenic equipment and principles used in human reproductive medicine are directly applicable to wildlife conservation, and the two fields share both technology and scientific knowledge.
Reciprocal IVF, also called co-IVF, partner IVF, or shared motherhood IVF, is a form of assisted reproduction used by female same-sex couples in which one partner provides the eggs and the other partner carries the pregnancy. The eggs are retrieved from the first partner, fertilised with donor sperm, and the resulting embryo is transferred to the uterus of the second partner. Both partners are biologically involved: one as the genetic mother and one as the gestational mother.
Reciprocal IVF depends on cryopreservation because it is rarely possible to synchronise the egg retrieval cycle of the first partner with the optimal endometrial preparation cycle of the second partner for a fresh transfer. Vitrifying the embryos after fertilisation and transferring them in a subsequent cycle resolves this timing challenge. In the UK, reciprocal IVF is permitted in HFEA-licensed facilities. Cryolab supplies vitrification equipment, liquid nitrogen storage tanks, and cryoshippers to IVF clinics offering reciprocal IVF programmes across the UK.
Mitochondrial donation, also called mitochondrial replacement therapy (MRT), is a specialist IVF technique used to prevent the transmission of serious mitochondrial diseases from mother to child. It involves creating an embryo in which the nuclear DNA comes from the intended parents but the mitochondrial DNA comes from a healthy donor. Two techniques have been developed: pronuclear transfer (PNT) and spindle transfer.
The UK was the first country in the world to legalise mitochondrial donation, under regulations passed in 2015. The first UK babies born following mitochondrial donation treatment were reported in 2023. The technique is subject to specific HFEA licensing and case-by-case approval. Cryopreservation is involved where embryos created through mitochondrial donation are vitrified for future use, following the same protocols and using the same liquid nitrogen storage infrastructure as standard IVF embryo cryopreservation.
Liquid nitrogen boils at -196 degrees Celsius at standard atmospheric pressure at sea level. As altitude increases, atmospheric pressure decreases and the rate of evaporation from an open dewar increases. For most laboratory applications at altitudes up to 2,000 metres this effect is minor, but at very high altitudes it becomes more significant and must be accounted for in storage management.
For air transport, commercial passenger aircraft maintain cargo hold pressure typically at the equivalent of 2,000 to 2,500 metres altitude. Cryoshippers used for air transport must be designed and validated to perform correctly at this reduced pressure. The CryoStork V2 is designed and validated for air transport, maintaining cryogenic temperatures in the cargo hold pressure environment of commercial aircraft. IATA regulations require that dry shippers with no free liquid nitrogen can vent without creating pressure buildup, which is one of the reasons that free liquid nitrogen is prohibited on commercial aircraft while correctly charged dry shippers are permitted.
The environmental footprint of liquid nitrogen production and cryogenic storage is a question that laboratory and clinical sustainability leads are increasingly asked to address as healthcare organisations set net-zero targets. Liquid nitrogen is produced by fractional distillation of liquid air, a process that requires significant electrical energy. The carbon intensity of liquid nitrogen production therefore depends directly on the carbon intensity of the electricity used. As the UK electricity grid decarbonises through increasing renewable generation, the embodied carbon of liquid nitrogen produced and used in the UK will fall accordingly.
Within the laboratory, cryogenic liquid nitrogen storage tanks have a significant sustainability advantage over mechanical refrigeration alternatives: they have no moving parts, no compressors, and no refrigerant circuits. They consume no electricity for cooling. A well-maintained vacuum-insulated dewar holds -196 degrees Celsius passively, using only the vacuum insulation to maintain temperature. This compares favourably with -80 degree ULT freezers, which consume substantial continuous electrical power. For the deepest storage temperatures required in biological preservation, liquid nitrogen storage is not only the scientifically correct choice but frequently the most energy-efficient one as well.
A liquid nitrogen supply disruption is a foreseeable operational risk for any IVF clinic or biobank that depends on LN2 for biological sample storage. Industrial gas supply chains can be affected by manufacturing plant outages, transport disruptions, demand surges, or weather events.
The first line of defence is holding time. A liquid nitrogen storage tank with a long holding time, such as the CryoCan 47-10 or CryoNest XL, provides a substantial buffer between a missed delivery and a temperature excursion. The second line of defence is a documented emergency supply arrangement with a secondary LN2 supplier, tested periodically. The third element is a sample transfer protocol: if a tank’s LN2 level falls to a pre-defined alarm threshold, there must be a documented procedure for transferring samples to a backup vessel before the temperature rises above -130 degrees Celsius. The HFEA requires that licensed clinics have documented contingency plans for storage equipment failure, which encompasses LN2 supply disruption. Contact Cryolab to discuss contingency planning for your clinic’s cryogenic storage operations.
The vacuum is maintained, not permanent
Most people assume a stainless steel vessel with no moving parts should last indefinitely. It does not. The insulation is the evacuated annulus between the inner and outer shells, and that vacuum degrades over time because materials inside the annulus outgas slowly for years and because hydrogen and helium migrate through steel. That migration is a property of the metal rather than a defect in the welding.
What the getter does, and why it runs out
Manufacturers fit a getter, a chemically active material that absorbs stray gas molecules as they appear, sometimes paired with an adsorbent doing the same job at cryogenic temperature. Its capacity is finite. When it saturates, annulus pressure creeps up and thermal performance follows it down.
Why you will not see it happen
No component fails, there is no alarm state and nothing visibly breaks, so the failure is inferred from rising nitrogen consumption rather than observed. Our guide to vacuum insulated cryogenic storage tanks covers the full sequence, and our cryogenic storage vessels are listed with their specifications.
Static evaporation rate is the honest comparator
Capacity and purchase price dominate most procurement conversations, and neither tells you what the vessel will cost to run. Ask instead for the static evaporation rate, sometimes called the normal evaporation rate or NER, expressed as litres lost per day or as a percentage of capacity per day, measured with the vessel closed and undisturbed under defined conditions.
A larger vessel with a poor rate can cost more to run than a smaller one with a good rate, so comparing capacities alone hides the difference that matters across ten years of ownership.
Three questions that rarely get asked
What does the warranty cover specifically in respect of the vacuum, since that is the component that determines service life. What is the end of life position, because a saturated getter is not a repair job on most designs. And what neck diameter is offered, since a wide neck eases retrieval while increasing heat ingress.
Where to start
Our cryogenic storage vessels are listed with specifications, and the reasoning behind each question is set out in the cryopreservation equipment procurement guide.
What the published figure actually measures
The static evaporation rate is measured with the vessel closed and undisturbed. It is a laboratory baseline under defined conditions, not a prediction for a working store room.
What your store adds to it
Your vessel gets opened. Every lid lift, every cane retrieval and every warm object introduced adds heat that the measurement never accounted for. A busy IVF store running at several multiples of its static rate is behaving normally rather than indicating a fault.
What to monitor instead
The absolute number stops being useful the day the vessel arrives. Establish your own baseline in litres per week, in your own room, at your own workload, and watch the trend. A steady rise at unchanged workload is a vacuum question, and it is the earliest warning this failure mode gives you.
A daily dipped level using a 100 cm dipstick alongside a logged fill record will tell you more than any single reading. Further detail in our article on vacuum insulated cryogenic storage tanks.
The early signal
Consumption rising steadily across months at unchanged workload, and hold time falling below what the same vessel achieved the previous year. Neither is dramatic, which is why both are usually missed until somebody plots the fill log.
The visible signal
Frost or condensation on the outer shell where there was none before, typically appearing first near the base or around a support point. Any cold spot on an outer surface that should be at room temperature means heat is conducting straight through the annulus. By this stage the vessel is well into failure.
The signal nobody logs
A vessel that has been dropped, struck or transported roughly and has behaved differently since. A knock can crack a weld or fracture an internal support without leaving any visible mark.
What to do about it
A degrading vacuum does not recover and the rate of deterioration accelerates once it begins. Transfer the contents and take the vessel out of service rather than monitoring it in place. The full sequence is set out in our guide to vacuum insulated cryogenic storage tanks.
Vacuum alone does not stop radiation
Heat reaches liquid nitrogen by conduction, convection and radiation. Evacuating the annulus largely removes convection and conduction is limited to what the neck, supports and pipework must structurally carry. Radiation needs its own answer.
How multilayer insulation works
Superinsulation wraps the inner vessel in many alternating layers of reflective film and low conductivity spacer. Each reflective layer returns radiant heat. The spacers exist to stop those reflective layers touching one another, because two foils in contact form a conduction bridge and undo the benefit entirely.
Why bulk tanks are different
Larger bulk vessels commonly use perlite in the annulus instead, a fine expanded volcanic glass powder, also under vacuum. The distinction matters at service time, because a perlite filled annulus cannot simply be opened, re-wrapped and pumped down on site the way some smaller vessels can.
More on the construction in our article on vacuum insulated cryogenic storage tanks.
Design and construction
Static vacuum insulated vessels are covered by the BS EN 13458 series, which runs to three parts covering fundamental requirements, design and fabrication with inspection and testing, and operational requirements.
Storage at your premises
BCGA Code of Practice 36 addresses cryogenic liquid storage at users premises. It sets out the safety device arrangement, including the requirement for the inner vessel to carry at least two independent safety devices, typically a pressure relief valve and a separate bursting disc, and for the outer jacket to have its own relief device set to open at not more than 0.5 bar.
Where pressure law applies
Vessels operating above 0.5 bar gauge fall within the Pressure Systems Safety Regulations 2000, which require a written scheme of examination drawn up by a competent person. Open neck storage dewars vented to atmosphere generally sit outside that regime, but remain vacuum insulated vessels in every other respect.
Our article on liquid nitrogen tank pressure covers the pressure side in detail.
It cuts both ways
A wide neck makes retrieval easier and faster, which reduces the time samples spend in warm vapour during access. It also increases heat ingress, because the neck is one of the few remaining conduction paths into an otherwise evacuated vessel.
How to decide
The right compromise depends on how often you go into the vessel. A store accessed several times a day benefits from the wider neck, because repeated slow retrievals through a narrow opening carry their own risk to the samples. A long term archive accessed rarely should favour the narrower neck and the lower evaporation rate that comes with it.
What this means in practice
This is a workload decision rather than a specification default, and it should be settled before the order rather than discovered afterwards. Ask for the static evaporation rate against the neck option you are actually buying, not the best case in the range. Our cryogenic storage vessels are listed by capacity and configuration.
The current position
Since 1 July 2022, UK patients can store eggs, sperm and embryos for up to 55 years, provided they reconsent every ten years. This replaced the previous ten year limit.
Why this is an equipment question, not just a paperwork one
Most laboratories updated their consent documentation within weeks of the change. Far fewer revisited their storage estate. A vessel specified against a ten year horizon is now expected to hold samples for a period longer than most of the staff handling them will work in the sector.
What it changes
Capacity planning stops being a rolling problem and becomes a cumulative one, vessel replacement becomes a recurring documented operation rather than a rare event, and consent status has to be tracked against a ten year reconsent cycle for every stored sample.
We have set out the operational consequences in full in our article on embryo cryopreservation under the 55 year limit.
The old behaviour
Under the previous ten year limit, storage was substantially self clearing. Samples left at a rate that roughly matched intake, so capacity planning was a rolling exercise conducted against a broadly stable inventory.
The new behaviour
Under the current limit, outflow reduces to a trickle and inventory accumulates. The store grows and keeps growing, which is a different shape of problem entirely.
Why models carried over from before 2022 fail
A capacity model calibrated on the old regime systematically underestimates. Sizing a vessel against current inventory rather than projected accumulation is the most common route to a vessel reaching capacity within two years of installation, and the remedy at that point is another vessel.
Model intake against withdrawal honestly and most units find they need capacity sooner than their vessel count suggests. Our cryopreservation equipment procurement guide works through the sizing questions.
No, and the gap is large
Samples may be retained for up to 55 years. A vacuum insulated vessel does not last anything like that, because the getter maintaining the annulus vacuum has a finite capacity and performance declines once it saturates.
What that means operationally
Stored samples will outlive several generations of vessel. Transfer between vessels therefore becomes a planned, repeated and documented operation rather than an exceptional event associated with equipment failure.
Why that matters more than it sounds
Every transfer is a warming exposure. Repeated exposures are cumulative, and the damage they cause is not visible at the time. This argues for treating transfer as a defined procedure with its own standard operating procedure, timing discipline and audit trail, rather than as an ad hoc job performed when a vessel is replaced.
The reasoning is set out in our articles on the 55 year storage limit and on vacuum insulated cryogenic storage tanks.
Not room temperature
The assumption is that the risk is a sample reaching ambient. It is not. Below roughly -130°C biological material sits in the glassy state, where molecular motion has effectively stopped and degradative reactions have ceased.
The band that matters
The risk lies between approximately -130°C and -80°C. Molecular motion has resumed while the sample still appears frozen. Ice recrystallisation occurs in this band, and it is both cumulative across exposures and undetectable at the time.
Why it goes unrecorded
A sample spending thirty seconds longer than intended in warm vapour during a routine retrieval gives no indication of the fact. The damage is written into the sample and not into the laboratory record, which makes retrieval and transfer technique a storage variable rather than purely a handling matter.
More on this in our article on embryo cryopreservation under the 55 year limit.
Two different methods
Slow controlled rate freezing lowers temperature at a programmed rate, typically a fraction of a degree per minute, allowing water to leave the cell gradually under a relatively low concentration of cryoprotectant. Vitrification uses a very high cryoprotectant concentration in minimal volume, cooling fast enough that the solution passes through the crystallisation range without forming ice at all.
Where the risk sits in each
Slow freezing was equipment dependent and comparatively tolerant of operator variation. Vitrification is the reverse. Loading volume, exposure time in the cryoprotectant and the interval between removing the carrier from the media and plunging it are all operator controlled, and all of them are measured in seconds.
The practical consequence
Vitrification has largely displaced slow freezing for oocytes and embryos in routine practice, but it relocated risk rather than removing it, moving it from the equipment to the operator and shortening the window in which an error occurs. Training and timing discipline matter more than they did.
Yes, and it is not a small one
Vitrification has largely displaced slow freezing for oocytes and embryos in routine IVF practice. It has not displaced controlled rate freezing across the wider field.
Where slow freezing remains the method of choice
Sperm freezing, and a substantial proportion of tissue and cell banking work, continue to use slow programmable freezing, largely because sample volume makes vitrification impractical. A programmable freezer is the only route to a controlled cooling profile at those volumes.
What this means for equipment planning
A laboratory performing both needs both. That is worth stating explicitly in a business case, because to anyone reviewing line items without clinical context two freezing methods read as duplication and one of them gets removed.
Match chamber size to batch size rather than to available budget. Our CBS Digitcool controlled rate freezers run across a range of chamber sizes for exactly this reason.
The two options
Open carriers place the sample in direct contact with liquid nitrogen and achieve the highest cooling rate. Closed carriers seal the sample inside a straw or device before cooling, accepting a slightly slower rate in exchange for eliminating contact.
What the argument is actually about
Cross contamination. Liquid nitrogen is not sterile and can carry viable organisms between samples held in a shared vessel. Against that, documented transmission in clinical practice is vanishingly rare, so closed systems trade a measurable reduction in cooling rate against a largely theoretical risk.
Why a documented position matters
Both positions are defensible on the evidence. What is not defensible is having no decision recorded, no rationale written down and no justification available when an inspector asks.
It is also worth revisiting a position adopted under the previous storage regime, because the arithmetic of low probability events across a fifty year store differs from that across a ten year one. Closed system consumables are available in our storage accessories range.
What good practice asks for
ESHRE’s 2026 good practice recommendations for the IVF laboratory state that cryostorage tanks should be continuously monitored with alarm systems that detect and log any out of range temperature or LN2 level. There are two requirements in that sentence, detection and logging, and a number of systems satisfy only the first.
Which probe to specify
ASRM’s 2020 cryostorage opinion recommends level probes in the liquid rather than temperature probes in the vapour, on the basis that level falls first. Vapour phase temperature is a lagging indicator. If you are specifying monitoring, specify the measurement that moves first.
The part that gets cut
The relay to a building management system or an autodialler, and a named responder who can be reached outside working hours. A tank alarm sounding in an empty laboratory at two in the morning has told nobody anything.
Larger vessels such as our CryoBank Series are listed with level, temperature and power alarms and a remote alarm output.
The failure is slow and silent
In March 2018 two unrelated fertility clinics in the United States suffered cryogenic storage failures on the same weekend, and thousands of eggs and embryos were lost. The conclusion drawn across the sector was not about equipment brands. It was that failures of this class develop gradually and produce no signal until they are well advanced.
Why nothing announces it
A vessel losing vacuum does not stop working. It becomes progressively worse at its job while looking identical from the outside. There is no fault state to read and no component that has failed, so a store without continuous monitoring is relying on somebody happening to walk past it and notice frost.
What closes the gap
Continuous level and temperature monitoring, alarms that reach a person outside working hours, oxygen depletion monitoring for the people in the room, and a written escalation procedure that has been tested rather than filed. Those four things are the difference between a maintenance job and an incident.
The requirement has changed
Under a ten year storage limit, labelling had to survive a decade. Under the current 55 year limit it has to remain legible far longer, and it has to survive staff turnover, changes of laboratory information system, relocation of the store and several transfers between vessels.
What that rules out
Anything that relies on adhesive performing at cryogenic temperature over long periods, and any identification scheme that only makes sense to the person who devised it. Handwritten marking that was legible on day one is frequently not legible after repeated frosting and handling.
What to specify
A label printer and label stock rated for cryogenic exposure, cryomarkers, and colour coded identification tabs so a cane can be located visually before it is lifted. Every straw format in the laboratory should have a documented path to a specific canister position, and that path needs to be readable by somebody who did not set it up.
Labelling and identification options are listed under storage accessories.
The vessel can travel, the person should not
A lift is a small, sealed, unventilated volume with a door that does not open on demand. Liquid nitrogen boils off continuously, and one litre of liquid becomes roughly 683 litres of gas at room temperature, a figure published in BCGA Code of Practice 30.
Why there is no warning
Nitrogen is inert, colourless and odourless and already makes up most of the air. The body has no sensor for it and none for falling oxygen. CP30 states that asphyxia due to oxygen deficiency is often rapid with no prior warning to the victim.
The rule to write down
Vessels travel in lifts alone. Send it up, take the stairs, and meet it at the other end. It costs nothing and removes the scenario entirely.
More on room and handling controls in our article on liquid nitrogen tank safety, and personal protection is covered in our cryogenic workwear range.
The published thresholds
HSE recommends that workplace oxygen remains above 19.5 per cent. The University of St Andrews applies two trigger points in its own procedure, 19.5 per cent for urgent investigation and 18 per cent for immediate evacuation.
Why to use published values
At an inspection you will be asked where your numbers came from. Adopting figures that are already published and defensible is considerably easier than justifying locally derived ones.
Where the alarm indicator belongs
On the outside of the door. A monitor alarming inside the room warns somebody who is already in it and already breathing whatever is there. Moving the indicator to the outside face of the door changes who receives the warning and when, and it costs almost nothing.
Ventilation should be sized for every litre of liquid in the room, including delivery dewars parked there temporarily. A room that was adequately ventilated for one vessel is not automatically adequate for three. Full detail in our article on liquid nitrogen tank safety.
The sequence most purchase orders get wrong
The vessel is the largest line, carries the longest lead time and needs the highest approval, so it reaches procurement first. It is also the item most constrained by decisions that have not yet been made.
The dependency chain
Straw format determines which goblets are compatible. Goblet selection determines canister layout. Canister layout determines the rack configuration and neck required in a vessel. The vessel is therefore the last decision in the chain rather than the first.
The test to apply before signing
Every straw format intended for use in the laboratory should have a documented path to a specific canister position. Where that path cannot be written down, the specification is incomplete however finished the purchase order looks.
The common failure is a straw format chosen months later, after goblets and canes have been purchased, that does not fit the organisation system already in place. Nothing is faulty and nothing is under warranty, and the tank furniture is simply reordered. Our cryopreservation equipment procurement guide sets out the full order of decisions.
The published figure
Static evaporation rate is quoted as litres per day or a percentage of capacity per day, measured with the vessel closed and undisturbed. It is a comparison figure between vessels rather than a prediction for your room.
What your store adds
Every lid lift, retrieval and warm object introduced adds heat the measurement excluded. A busy IVF store commonly runs at several multiples of its static rate without anything being wrong. Establish your own litres per week baseline and watch the trend rather than the absolute number, because a sustained rise at unchanged workload is the earliest sign of vacuum degradation. See choosing a liquid nitrogen storage tank.
What it is
A double walled container with the space between the walls evacuated and sealed. That vacuum is the insulation. There is no foam or fibre in the wall, and the steel is a way of holding the vacuum in place.
What distinguishes one from another
Neck diameter, static evaporation rate, rack and canister configuration, and the quality of the vacuum itself. Capacity is the least informative figure on the datasheet, because it tells you nothing about running cost or daily usability. Ranges are listed under storage vessels, with the mechanism explained in vacuum insulated cryogenic storage tanks.
Open neck dewars
A storage dewar is not a pressure vessel. The lid is a loose insulating plug and the neck vents to atmosphere, which is why the boil off escapes as the plume you see at the neck.
Pressurised supply vessels
These are built to hold pressure and carry relief valves and bursting discs for the purpose. BCGA Code of Practice 36 requires at least two independent safety devices on the inner vessel, with the outer jacket relief set to open at not more than 0.5 bar.
The distinction matters because the two fail differently and are regulated differently. More in liquid nitrogen tank pressure explained.
What to establish first
Sample format and organisation system, access frequency, liquid or vapour phase preference, and the floor space and door widths on the route in. Those five determine the specification more than capacity does.
What to ask any supplier
Static evaporation rate and what it converts to as a weekly nitrogen order. Whether monitoring is included. Whether racks and canisters are matched to your straw format or to a reference format. Cryolab supplies dewars and storage vessels to IVF clinics, NHS trusts, biobanks and research facilities in the UK and internationally, and you can speak to us with those five answers.
Ventilation sized for the room today
Extract ventilation must be sized for every litre of liquid present, including delivery dewars parked temporarily. Cryo stores drift rather than fail: a room commissioned around one vessel acquires a second and a third, and nothing announces the change.
Monitoring and access
Fixed oxygen monitoring with the alarm indicator on the outside of the door, so it warns the person who has not yet entered. A route in that the vessel actually fits, checked at door widths rather than assumed. And a standing rule that vessels travel in lifts alone. Full detail in liquid nitrogen tank safety.
The short answer
No. Liquid phase is colder and more stable, because the sample is immersed in liquid at its boiling point rather than held in vapour above it.
The gradient that follows
In vapour phase, the top of a canister sits warmer than the bottom. That matters because the damage band is between roughly minus 130 and minus 80 degrees, where molecular motion has resumed while the sample still looks frozen, and where ice recrystallisation is cumulative and invisible.
Vapour phase is chosen for contamination control rather than for temperature, and it raises the importance of level monitoring accordingly. Options under storage vessels.
Access comes first
Embryo storage is typically a working store rather than an archive, which argues for a neck and rack configuration that makes retrieval quick and safe, accepting the higher heat ingress that comes with it.
Monitoring that logs
The ESHRE recommendations on Good Practice in the IVF laboratory, published in Human Reproduction (41(8), 1245), state that cryostorage tanks should be continuously monitored with alarm systems that detect and log any out of range temperature or LN2 level. Detection alone meets half the requirement.
Size against accumulation rather than current inventory, since storage no longer self clears. See choosing a liquid nitrogen storage tank.
What happens to the sample
Below roughly minus 130 degrees, biological material enters the glassy state. Molecular motion effectively stops and degradative reactions cease. A sample warmed after twenty years carries the biological age it had on the day it was frozen.
What actually limits storage
Two things, and neither is the sample. The regulatory limit, which the Human Fertilisation and Embryology Authority confirms is up to 55 years in the UK with reconsent every ten years. And the vessel, which does not last that long, so transfers are inevitable. See embryo cryopreservation under the 55 year limit.
More than the container
The vessel holds the liquid nitrogen and the samples, but it does not work alone. It needs racking and canisters matched to your sample format, a refill routine and the dispensing equipment to support it, monitoring with an alarm path that reaches somebody, and PPE for the people using it.
Why that matters at purchase
Budgets built from a single line item run short, because the surrounding items arrive as surprises after the order is placed. The full set is listed in the cryopreservation equipment procurement guide, with ranges under storage vessels.
Layout and access
Vessels need clear space around them for lid removal and canister lifting, a route wide enough for a trolley, and positioning that does not block the door or the ventilation. Roller bases matter more than they sound, because a vessel being dragged is a vessel about to be dropped.
Records and identification
A sample map that survives staff turnover, colour coded identification at cane level, and a fill log recording date, vessel and litres. The log does a second job as an early warning of vacuum degradation. Identification components are under storage accessories.
The recurring half
Nitrogen consumption, set by static evaporation rate and by how often the store is opened. Across a decade the gap between a good rate and a poor one routinely exceeds the purchase price difference between two vessels.
The other lines
Monitoring and its relay off site. Where a vessel operates above 0.5 bar gauge, the written scheme of examination required under the Pressure Systems Safety Regulations 2000. And eventual replacement, because the getter maintaining the vacuum has finite capacity. The drivers are set out in liquid nitrogen container price.
What separates suppliers
Whether they will put static evaporation rate and expected nitrogen consumption in writing. Whether they calculate capacity against your straw format rather than a reference format. Whether they support the equipment after delivery, and whether they can advise on the consumable chain rather than only the vessel.
About Cryolab
Cryolab was established in 2000 and holds ISO 9001:2015 certification from BSI. We supply cryogenic equipment, consumables, accessories and servicing to IVF clinics, NHS trusts, biobanks and research facilities in the UK and internationally, and we are exclusive UK and Ireland distributor for CryoBioSystems. Speak to us.
What it does
Cryogenic storage holds material below roughly minus 130 degrees, where molecular motion effectively stops and degradative reactions cease. That is a different proposition from a mechanical minus 80 freezer, where motion has not stopped and slow damage accumulates over months and years.
Where it is used
IVF and fertility, sperm and embryo banking, blood and tissue banking, cell banking and research. Anywhere material has to be recoverable in the same condition years later rather than merely kept cold. Equipment options are under storage vessels.
Before the sale
Capacity calculated against your own formats. Static evaporation rate and weekly nitrogen order in writing. A view on whether your straw, goblet and cane chain actually fits the vessel being quoted, offered before the order rather than after.
After the sale
Servicing, consumable supply, and support when something behaves unexpectedly. A vessel is a decade long relationship rather than a transaction, and the supplier who cannot answer a question in year three is the wrong one in year one. Speak to Cryolab.
The six categories
Storage vessels. Nitrogen supply and refill equipment. Freezing method, whether vitrification consumables or a controlled rate freezer. Consumables and sample organisation. Monitoring and alarms. Protective equipment.
Why lists run short
Procurement usually receives three lines: a tank, some straws and nitrogen. The finished list runs to around forty items, and several get ordered late because their necessity is not apparent at specification stage. The full list is in the cryopreservation equipment procurement guide.
Two categories, and laboratories tend to buy one and forget the other. The first is personal protective equipment: cryogenic gloves that are loose enough to be shaken off instantly, a full face shield rather than safety glasses alone, a long apron that sheds splashes away from the body, and closed footwear with trousers worn outside the boot so liquid cannot run in at the ankle. Cryolab supplies these through its cryogenic workwear range.
The second is the room itself. Nitrogen is colourless and odourless and displaces oxygen without any warning sign, so fixed oxygen depletion monitoring in the storage room, and anywhere nitrogen is decanted, is the control that protects staff who are not wearing anything at all when they walk in.
Because the hazard gives you no sensory warning. One litre of liquid nitrogen expands to roughly 683 litres of gas at room temperature, so a modest spill or a vent in a small unventilated room can drop the oxygen concentration below breathable levels in a short time. Nitrogen has no smell and no colour, and the early effects of oxygen deficiency impair judgement before the person recognises anything is wrong.
Fixed monitoring with an audible and visual alarm outside the door, so it is seen before entry rather than after, is standard practice. Alarm points are commonly set at 19.5 per cent oxygen for the first stage, with a second, lower alarm below that. Set points and siting should follow your own risk assessment and current BCGA guidance rather than a default from the supplier.
Cryogenic gloves, and the fit matters more than the material. They must be loose at the wrist so that if liquid gets inside, the glove can be shaken off immediately rather than holding the liquid against the skin. A tight, sealed glove is more dangerous than no glove at all in that scenario.
Cryogenic gloves are splash protection, not immersion protection. They are not rated for dipping a hand into liquid nitrogen and should never be treated as if they were. Length should suit the task: wrist length is adequate for handling a canister lid, but retrieving from a deep vessel calls for elbow or shoulder length. Cryolab stocks the range under cryogenic workwear.
On a trolley designed for the vessel, and never in a passenger lift with people in it. The standing rule on most sites is that nitrogen travels in a goods lift unaccompanied, with staff meeting it at the other end, because a lift car is precisely the small unventilated space where a vent or a spill becomes dangerous.
The vessel itself should be moved upright, secured, and never tilted or dragged by the neck. Route matters as much as the equipment: plan the journey so it avoids corridors where a spill would trap people, and make sure the receiving area is ventilated and monitored. All of this belongs in a written procedure and a risk assessment rather than in individual habit.
Leave, and take others with you. A spill of any size produces a large volume of cold nitrogen gas that pools at floor level before it disperses, so the first action is evacuation and not clean up. Close the door behind you, raise the alarm and do not re-enter until oxygen monitoring confirms the room is safe.
Liquid nitrogen evaporates on its own and needs no treatment. What needs managing is ventilation, exclusion and the period afterwards, because the floor, the fittings and anything the liquid touched will stay cold enough to cause a cold burn long after the visible vapour has gone. If someone has skin contact, flush the area with tepid, not hot, water and seek medical advice.
There is no single interval that covers every vessel, because the obligations differ by type. A pressurised vessel operating above 0.5 bar above atmospheric pressure falls under the Pressure Systems Safety Regulations 2000, where the intervals are set by a written scheme of examination drawn up by a competent person rather than chosen by the user. An open necked storage dewar sits outside that regime and is governed by the manufacturer’s guidance and your own risk assessment.
Alongside whatever formal schedule applies, the daily and weekly checks do more to catch problems early: a logged pressure reading on pressurised vessels, a level check, a look at the relief devices and the outer shell for frost, and a nitrogen consumption figure in litres per week. A steady rise in consumption at unchanged workload is the earliest practical warning that a vacuum is degrading, and it appears long before anything looks wrong.
It depends on what has failed. Valves, relief devices, gauges, level indicators, roller bases and lids are serviceable items and are routinely replaced. A pressure building regulator that is passing or stuck can be changed without touching the vessel itself.
The vacuum is different. Where the annulus has lost its vacuum, whether through a weld failure, a mechanical shock or a getter that has reached the end of its capacity, the practical answer for most laboratory vessels is replacement rather than repair. Re-evacuation is possible on some designs but it is specialist work, it does not address the cause, and a vessel that has lost vacuum once in service is not a vessel to trust with irreplaceable material.
The decision point is usually the samples rather than the vessel. Anything holding material that cannot be replaced should come out of service at the first reliable sign of vacuum loss, not at the point of failure.
Liquid nitrogen boils at minus 195.8 degrees Celsius at atmospheric pressure, and samples immersed in the liquid sit at that temperature. That is the figure for liquid phase storage, and it is stable throughout the vessel because the liquid holds the whole canister at the boiling point.
Vapour phase storage is different and this is where the specification matters. Samples sit above the liquid in cold gas, so there is a vertical temperature gradient: the bottom of a canister is close to the liquid temperature while the top is warmer, and how much warmer depends on the vessel design, the liquid level and how often the lid is opened. This is why vapour phase vessels are far less tolerant of the liquid level being allowed to fall, and why the level alarm matters more in vapour phase than in liquid phase.
The temperature to design around is the warmest point a sample can occupy, not the temperature at the bottom of the vessel.
Because consumption is the only continuously available measurement of vessel health. Everything else is a periodic check. Nitrogen use is happening all the time, and it responds to problems long before they are visible.
The figure to track is litres per week in your own room, at your own workload, established as a baseline once the vessel is installed and settled. The manufacturer’s static evaporation rate is measured with the vessel closed and undisturbed, so it is a laboratory benchmark rather than a prediction. Real consumption is always higher, and a busy store running at several multiples of its static rate is normal rather than faulty.
What matters is the change. A steady rise at unchanged workload is a vacuum question and typically appears months before frost is visible on the outer shell. A sudden jump usually points at workload, a lid left open or a change in decanting practice. Logging the number is what makes the distinction possible.
Four hazards, each with its own controls. Oxygen depletion, because nitrogen is odourless and one litre of liquid becomes roughly 683 litres of gas, which is what drives the requirement for room ventilation and fixed oxygen monitoring. Cold burns and cold contact, which drives the PPE specification and the rule that gloves must be loose enough to shake off. Pressure, covering relief devices, trapped liquid between closed valves, and whether the Pressure Systems Safety Regulations 2000 apply to the vessel. And manual handling, covering how vessels are moved, on what, by whom, and through which route.
Beyond the hazards, the assessment should name the lifting and transport arrangements, the lift policy for moving nitrogen between floors, what happens in a spill, what happens on a monitor alarm, and who is authorised to decant. It should also cover the samples themselves, since a storage failure is a loss event as well as a safety event.
Assessments should be reviewed when the vessel, the room, the workload or the staffing changes, not only on an annual cycle.
From industrial gas suppliers and from specialist cryogenic suppliers, and the right route depends on what you need alongside the liquid. Gas companies supply the nitrogen itself, typically as bulk delivery to a static tank, as portable pressurised vessels on exchange, or through depot collection. Specialist suppliers cover the equipment that holds and dispenses it: storage vessels, dispensing dewars, transfer hoses and the safety equipment around them.
Most laboratories end up with both, a gas contract for the liquid and an equipment supplier for everything else. Choose the supply mode on consumption stability rather than unit price, since bulk needs a permanent installation and a steady draw to make sense, and cylinder delivery suits most IVF and research units.
There is no list price in the way there is for a consumable. It depends on your supply arrangement, whether bulk, cylinder or self collect, on delivery frequency, on volume and on prevailing supply conditions. Any figure published online is wrong for most readers by the time they read it.
What is more useful than a price per litre is the question of how many litres you will actually consume, and that is driven by the static evaporation rate of your vessels rather than by how many samples you handle. A vessel with a poor rate raises your recurring nitrogen cost for its whole working life, which is why the cheapest vessel on a quotation is often the most expensive decision on the page.
Three ways. Bulk delivery fills a static tank from a tanker, which needs a permanent external installation with vehicle access and a prepared base, and it suits high steady consumption. Cylinder or portable vessel delivery brings pressurised vessels on exchange, with no fixed installation and the ability to scale the order, which is where most IVF laboratories sit. Self collect means taking your own dewar to a depot, which looks cheapest until staff time and the transport risk assessment are counted.
The delivery frequency in any of these is set by boil off rather than by usage, because a vessel loses nitrogen continuously whether anybody opens it or not.
A vacuum, and not insulation in the ordinary sense. There is an inner vessel, an outer jacket and an evacuated space between them, and heat cannot conduct or convect across a vacuum.
Three things inside that space determine how well it performs and for how long: multilayer insulation wrapped in layers to interrupt radiant heat, internal materials chosen and cleaned so that they outgas as little as possible, and a getter, a chemically active component that absorbs stray gas molecules and holds the annulus evacuated over years.
None of it is inspectable on delivery and none of it appears on a specification comparison, yet it accounts for most of the genuine price difference between two vessels of the same capacity.
Consumption tells you first. Log nitrogen use in litres per week in your own room at your own workload, and read it as a series rather than as a number. A steady rise at unchanged workload is a vacuum question.
On a pressurised vessel the pressure trend moves even earlier, because pressure responds to the rate at which liquid is turning to gas while the level only responds once the liquid has already gone. The level gauge is the next warning. Frost on the outer shell is the last one, and by that point the vacuum has degraded far enough for heat to reach the outer surface and the vessel usually needs to come out of service.
A vessel for moving frozen biological samples, most commonly a vapour phase dry shipper. It holds liquid nitrogen absorbed into a porous inner matrix rather than as free liquid, so samples travel in the vapour phase and the vessel can be inverted without spilling because there is no free liquid available to escape.
That construction is also what determines its regulatory treatment in air transport. Sizing follows sample format and count, journey length including a realistic delay allowance, and who has to lift it, rather than the largest capacity the budget allows. A bigger shipper is heavier for staff to handle and more expensive to ship, so oversizing costs twice.
Longer than a shipment usually needs and shorter than the published figure suggests. Published hold times are measured under favourable and clearly defined conditions: upright, unopened, at moderate ambient temperature.
Real shipments meet none of those reliably, because orientation changes in transit, ambient temperature varies considerably, customs holds happen without warning and every opening costs hold time that cannot be recovered. Treat the published figure as an upper bound under ideal conditions and build margin against the delay you have not planned for rather than the journey you have. A hold time quoted without stating the conditions under which it was measured is not usable for planning at all.
Two separate provisions, which are routinely confused. The shipper itself travels as not restricted under Special Provision A152 of the IATA Dangerous Goods Regulations, provided the packaging cannot build pressure or release nitrogen in any orientation and the air waybill carries the words not restricted together with the special provision number.
Packing Instruction 650 of the same regulations governs the biological samples inside where those are classified as UN 3373 Category B, and it applies to the samples rather than to the nitrogen holding them cold. A dry shipper is not exempt from PI 650, and PI 650 was never about the nitrogen. Getting either wrong produces a consignment held while somebody works out what it is.
Saturate the absorbent matrix fully, which takes appreciably longer than most protocols allow, then invert and drain the vessel so that no free liquid remains. Skipping the drain leaves free nitrogen inside, which changes both the regulatory position and the behaviour in transit.
Weigh the unit before and after and record both figures, because weight is the only practical measure of how much cold mass is genuinely in the vessel and the only check that catches a matrix which has not taken a full charge. Undercharging is the most common cause of a failed cryogenic transport. Treat the charging step as a safety operation as well: a freshly charged shipper should never share a lift with a person.
It depends on the vessel type and it should be written down rather than assumed. On a pressurised vessel: relief valve and bursting disc, pressure building coil and regulator, economiser where fitted, gauges, valves and connections, and the outer jacket relief device, which is small and easy to overlook.
On a storage dewar: lid and neck, roller base, level measurement, canisters and handles, labelling and inventory integrity, and a tested alarm with a confirmed out of hours relay. On a controlled rate freezer: chamber and probe calibration, nitrogen feed, profile records and alarm function.
What no service visit can confirm is the state of the vacuum, because that is a trend rather than a state, and the only instrument that measures it is your own consumption log.
It depends on pressure. The Pressure Systems Safety Regulations 2000 apply to systems containing a relevant fluid, which includes a gas or liquid under pressure greater than 0.5 bar above atmospheric pressure. A pressurised cryogenic vessel above that threshold falls in scope, and the user must have a written scheme of examination drawn up or certified by a competent person before the system is operated, with examinations carried out in accordance with it. HSE guidance INDG178 sets out the scope.
An open necked, non pressurised storage dewar sits outside that regime. Two points get missed: a written scheme is not the same thing as a service visit, and the duty sits with the user rather than the supplier, so buying compliant equipment does not discharge it.
Specialist cryogenic suppliers rather than general laboratory distributors, because the equipment carries regulatory obligations and a service life measured in decades.
What distinguishes them in practice is whether they will put figures in writing: the static evaporation rate, what that translates to as a weekly nitrogen order at your capacity, what the quotation includes and excludes, and who holds responsibility for periodic examination of the vessels.
Cryolab has supplied cryogenic equipment, consumables and servicing to IVF, blood banking, tissue banking and research laboratories since 2000, holds ISO 9001:2015 BSI Quality Management System certification, and is the exclusive UK and Ireland distributor for CryoBioSystems, a brand of ART.
Two categories, and laboratories tend to buy one and forget the other. Personal protective equipment: cryogenic gloves loose enough to shake off instantly, a full face shield rather than safety glasses alone, a long apron and closed footwear with trousers worn outside the boot.
And the room itself: fixed oxygen depletion monitoring wherever nitrogen is stored or decanted, because nitrogen is colourless and odourless and displaces oxygen with no warning sign at all. One litre of liquid becomes roughly 683 litres of gas at room temperature, which is what makes a small spill in an unventilated room dangerous.
BCGA Code of Practice 30 records that asphyxia due to oxygen deficiency is often rapid with no prior warning to the victim.
Preserving living biological material at temperatures low enough that biological activity effectively stops, so that it can be stored and later recovered.
In reproductive medicine that covers eggs, sperm and embryos, whether for treatment cycles, before medical treatment that may affect fertility, for donor programmes or for elective storage. Beyond fertility it covers cell lines, tissue, blood products and biobanked research material.
The common thread is that the value sits in material that cannot be replaced, which is why the storage side deserves the same specification effort as the freezing protocol. The protocol determines whether the sample survives the freeze. The storage determines whether it survives the next thirty years.
Vitrification is one method of cryopreservation, not an alternative to it. Cryopreservation is the general practice of preserving material at cryogenic temperatures.
Within it, slow freezing cools at a controlled rate so that ice forms outside the cell and progressively dehydrates it, while vitrification uses much higher cryoprotectant concentrations and much faster cooling so that water solidifies as a glass without organising into crystals at all.
Slow freezing is common for sperm and for many cell types. Vitrification is now standard for oocytes and embryos, and it works with very small sample volumes because the achievable cooling rate depends on volume.
Liquid nitrogen boils at minus 196 degrees Celsius at atmospheric pressure, and that is the temperature of the liquid phase in a storage vessel. Vapour phase storage is warmer and varies with height in the neck: near the liquid surface it is close to minus 190 degrees Celsius, and it rises steadily towards the top of the vessel. This is why storage position matters. Samples held high in the neck of a poorly filled vessel can sit well above the glass transition temperature of around minus 130 degrees Celsius, at which point molecular activity resumes and long term stability is no longer assured.
Serviceable parts can be repaired or replaced as a matter of routine: lids and neck plugs, castors, racking and canisters, level and temperature monitoring, hoses, valves and phase separators. Loss of vacuum in the annular space is a different matter, because on most laboratory storage vessels the vacuum jacket is not designed to be re evacuated in the field. A vessel that has lost its vacuum should have its samples moved to a known good vessel and then be replaced rather than kept in service.
The physics is the same but the operating pattern is not. Biobank vessels tend to hold large numbers of samples with infrequent retrieval, so they favour high capacity, automated filling and tight environmental monitoring. IVF storage involves frequent, individually identified access to a smaller inventory, where traceability, witnessing and minimising lid open time matter more than raw capacity. The regulatory position differs too: treatment and storage of gametes and embryos in the UK falls under the HFEA, which biobanking generally does not.
Only for material whose validated storage temperature is within the freezer’s range. A mechanical ultra low freezer typically holds minus 80 degrees Celsius, which is well above the glass transition point of around minus 130 degrees Celsius. Below that point molecular mobility effectively stops; above it, degradation continues slowly. Cells, gametes, embryos and anything intended for long term viability belong in liquid nitrogen storage. A mechanical freezer also depends on continuous power, whereas a vacuum insulated vessel holds temperature through an outage.
Size from three figures rather than headline capacity: how many samples you hold today, the growth you expect over the vessel’s service life, and how the samples are packaged, since canes, straws, cryovials and boxes pack very differently. Then consider working pattern. A vessel that is opened many times a day loses more nitrogen and warms its upper neck more than one opened weekly, so frequent access argues for a wider necked vessel with organised racking rather than simply a larger one. Fill interval and the practicality of refilling in your laboratory should also inform the choice.
The hazard is asphyxiation rather than toxicity. Nitrogen is inert and odourless, and it displaces oxygen without giving any warning that the atmosphere has changed. One litre of liquid nitrogen produces roughly 683 litres of gas as it warms, so a modest spill in a small, poorly ventilated room can pull the oxygen concentration down quickly. BCGA Code of Practice 36 treats 19.5 per cent oxygen as the level at which monitoring should be considered. The practical test is to work out the volume of your worst credible release, compare it with the free volume of the room, and decide ventilation and monitoring from that figure rather than from how large the vessel looks.
It depends on the room, not on the presence of liquid nitrogen. The judgement comes from a risk assessment that compares the gas volume of a credible release with the free volume and ventilation rate of the space. A single small dewar in a large, well ventilated laboratory may not warrant fixed monitoring. A bulk vessel, a filling point, a basement store, a lift lobby or any room with limited air changes usually does. Where the assessment concludes that oxygen could fall below 19.5 per cent, fixed monitoring with an alarm is the normal control, supported by a personal monitor for anyone entering alone.
Sensor position decides whether the alarm is useful. Cold nitrogen vapour is denser than air when it first evaporates, so it pools low before it warms and mixes, which argues for a sensor in the breathing zone and a second at low level near the likely release point. Put a repeater outside the door so nobody walks into a depleted atmosphere to check the reading. Keep sensors away from doorways, supply vents and draughts that will dilute the sample and mask a genuine fall. Record the calibration interval in the same log as your vessel servicing so it does not get missed.
Loose fitting cryogenic gloves with a gauntlet cuff, worn so they can be shaken off instantly. The purpose is splash protection and brief contact with cold surfaces, not immersion: no laboratory glove is rated for putting a hand into liquid nitrogen, and a tight glove that traps liquid against the skin is more dangerous than no glove at all. Gloves are one part of the set. Add a face shield over safety glasses whenever you are decanting or filling, closed shoes, and sleeves covered. Cuffs should sit outside the sleeve so that any splash runs off rather than into the glove.
A lift car is a small, sealed volume with almost no ventilation, and a lift can stop with somebody inside it. If a vessel vents or spills in that space the oxygen concentration falls fast and the occupant has nowhere to go. The accepted practice is that the vessel travels alone in the car while staff take the stairs and meet it at the destination floor, with the lift controlled at both ends so nobody steps in. Where this cannot be guaranteed, move the vessel by a goods lift or by a route that avoids enclosed cars altogether.
Cryogenic transport moves biological samples between locations using dry shippers, vessels in which liquid nitrogen is absorbed into a porous matrix leaving no free liquid. Storage is a controlled static environment managed continuously by trained staff. Transport hands control to couriers, airlines, and receiving teams. Every variable a laboratory normally controls becomes uncertain the moment the dry shipper leaves the building. IATA Dangerous Goods Regulations govern what vessels can travel by air and under what conditions. That regulatory boundary is precisely why dry shipper selection and documentation matter as much as the vessel engineering.
Fill the vessel with liquid nitrogen and allow the absorbent material to saturate fully. The correct indicator of saturation is not elapsed time. It is that the vessel stops accepting liquid nitrogen. Pour LN2 into the neck: a fully saturated vessel returns it immediately. If the vessel is still accepting nitrogen, it is still charging. Pouring out free nitrogen before saturation is complete reduces hold time unpredictably and is the most common cause of dry shipper failure in clinical practice. IATA Dangerous Goods Regulations Special Provision A152 requires no free liquid nitrogen to be present before loading, making correct charging a regulatory requirement, not only a performance one.
Special Provision A152 under IATA Dangerous Goods Regulations provides a complete exemption for correctly prepared dry shippers from the standard Class 2.2 non-flammable gas declaration that would otherwise apply to liquid nitrogen. A dry shipper meeting A152 conditions travels as “Not Restricted” on commercial aircraft. The air waybill must include the verbatim phrase “Not restricted, as per Special Provision A152” to claim the exemption. If any A152 condition is not met, the dry shipper reverts to full PI 202 regulation and most commercial couriers will refuse the shipment outright.
A peer-reviewed study in the Journal of Assisted Reproduction and Genetics found that following induced vacuum failure, small-capacity tanks showed evaporation rates increasing to 70 litres per day within three hours and reaching 90 litres per day at six hours, compared to under one litre per day with intact vacuum. A separate study in Fertility and Sterility found that surface temperature probes detected vacuum breach within nine minutes on average, giving approximately 19 hours before internal temperature reached the critical -140 degrees Celsius threshold. The most reliable early warning in routine monitoring is an unexplained increase in daily LN2 consumption, which will appear weeks before visible signs develop.
A storage dewar, also called a liquid nitrogen storage vessel or LN2 storage tank, is designed for static long-term storage at a fixed location. It contains free liquid nitrogen and is not IATA compliant for air freight. A dry shipper is designed specifically for transport. It uses an absorbent porous material to hold liquid nitrogen without free liquid, qualifies as “Not Restricted” under IATA Special Provision A152 when correctly prepared, and has a defined hold time determined at the point of charging. Using a standard storage dewar for air transport is not IATA compliant under any circumstances.
Vacuum integrity, the primary performance determinant of any liquid nitrogen storage dewar, is typically guaranteed by manufacturers for ten years under normal operating conditions, though many vessels perform beyond this. Research published in Springer Journal of Mechanical Science and Technology confirmed that vacuum loss doubles the boil-off rate of stored liquid nitrogen through natural convection in the space between tank walls. A vessel showing frost on its outer shell, unexplained LN2 consumption increases, or condensation should be assessed immediately and removed from active sample storage until its integrity is confirmed.
The HFEA Code of Practice sets minimum documentation requirements for the transfer of human reproductive material between licensed UK fertility facilities. The essential set is: a chain-of-custody form signed by both releasing and receiving facilities; a consent verification confirming both gamete providers have authorised the transfer; a sample identity record linking physical labels to the patient record at both ends; a temperature log confirming cryogenic conditions were maintained throughout transit; and a receiving facility acceptance record. The temperature log is the document most frequently absent, and its absence represents an HFEA compliance gap with no adequate retrospective remedy.
In liquid phase storage, samples are submerged directly in liquid nitrogen at -196 degrees Celsius. In vapour phase, samples are held above the liquid surface in nitrogen vapour at temperatures typically between -150 and -190 degrees Celsius depending on height within the vessel. The critical difference is contamination risk. Liquid nitrogen is not sterile, and in liquid phase storage any pathogen in the tank environment has direct contact with every stored sample. The HFEA Code of Practice increasingly reflects the expectation that vapour phase storage and closed carrier systems are the appropriate standard for licensed human reproductive material in the UK.
Manufacturers publish static hold time figures measured under controlled laboratory conditions: full vessel, sealed, upright, at approximately 20 degrees Celsius, with no access events. Functional hold time during a real transfer is lower because samples, access events, and handling all contribute heat load. A USPTO analysis of dry shipper engineering distinguishes explicitly between static and functional hold time. For clinical planning, hold time should be calculated against the maximum plausible journey time including delays, not the expected transit, and a meaningful safety margin should be built in above that figure.
Dry shipper prices in the UK market range from under £500 to over £3,000 for clinical-grade units. The variation reflects differences in hold time, absorbent material performance, canister configuration, construction quality, and IATA compliance certification. A comprehensive analysis of ISO 21973 GMP-grade cryogenic transport requirements confirms that not all vessels meeting the basic regulatory threshold deliver equivalent performance under real transit conditions. For reproductive medicine applications, the relevant comparison is not purchase price but cost per successful transfer, which includes the probability that the vessel maintains cryogenic conditions throughout a delayed or mishandled journey.
Cryogenic transport moves biological samples between locations using dry shippers, vessels in which liquid nitrogen is absorbed into a porous matrix leaving no free liquid. Storage is a controlled static environment managed continuously by trained staff. Transport hands control to couriers, airlines, and receiving teams. Every variable a laboratory normally controls becomes uncertain the moment the dry shipper leaves the building. IATA Dangerous Goods Regulations govern what vessels can travel by air and under what conditions. That regulatory boundary is precisely why dry shipper selection and documentation matter as much as the vessel engineering.
Fill the vessel with liquid nitrogen and allow the absorbent material to saturate fully. The correct indicator of saturation is not elapsed time. It is that the vessel stops accepting liquid nitrogen. Pour LN2 into the neck: a fully saturated vessel returns it immediately. If the vessel is still accepting nitrogen, it is still charging. Pouring out free nitrogen before saturation is complete reduces hold time unpredictably and is the most common cause of dry shipper failure in clinical practice. IATA Dangerous Goods Regulations Special Provision A152 requires no free liquid nitrogen to be present before loading, making correct charging a regulatory requirement, not only a performance one.
Special Provision A152 under IATA Dangerous Goods Regulations provides a complete exemption for correctly prepared dry shippers from the standard Class 2.2 non-flammable gas declaration that would otherwise apply to liquid nitrogen. A dry shipper meeting A152 conditions travels as “Not Restricted” on commercial aircraft. The air waybill must include the verbatim phrase “Not restricted, as per Special Provision A152” to claim the exemption. If any A152 condition is not met, the dry shipper reverts to full PI 202 regulation and most commercial couriers will refuse the shipment outright.
A peer-reviewed study in the Journal of Assisted Reproduction and Genetics found that following induced vacuum failure, small-capacity tanks showed evaporation rates increasing to 70 litres per day within three hours and reaching 90 litres per day at six hours, compared to under one litre per day with intact vacuum. A separate study in Fertility and Sterility found that surface temperature probes detected vacuum breach within nine minutes on average, giving approximately 19 hours before internal temperature reached the critical -140 degrees Celsius threshold. The most reliable early warning in routine monitoring is an unexplained increase in daily LN2 consumption, which will appear weeks before visible signs develop.
A storage dewar, also called a liquid nitrogen storage vessel or LN2 storage tank, is designed for static long-term storage at a fixed location. It contains free liquid nitrogen and is not IATA compliant for air freight. A dry shipper is designed specifically for transport. It uses an absorbent porous material to hold liquid nitrogen without free liquid, qualifies as “Not Restricted” under IATA Special Provision A152 when correctly prepared, and has a defined hold time determined at the point of charging. Using a standard storage dewar for air transport is not IATA compliant under any circumstances.
Vacuum integrity, the primary performance determinant of any liquid nitrogen storage dewar, is typically guaranteed by manufacturers for ten years under normal operating conditions, though many vessels perform beyond this. Research published in Springer Journal of Mechanical Science and Technology confirmed that vacuum loss doubles the boil-off rate of stored liquid nitrogen through natural convection in the space between tank walls. A vessel showing frost on its outer shell, unexplained LN2 consumption increases, or condensation should be assessed immediately and removed from active sample storage until its integrity is confirmed.
The HFEA Code of Practice sets minimum documentation requirements for the transfer of human reproductive material between licensed UK fertility facilities. The essential set is: a chain-of-custody form signed by both releasing and receiving facilities; a consent verification confirming both gamete providers have authorised the transfer; a sample identity record linking physical labels to the patient record at both ends; a temperature log confirming cryogenic conditions were maintained throughout transit; and a receiving facility acceptance record. The temperature log is the document most frequently absent, and its absence represents an HFEA compliance gap with no adequate retrospective remedy.
In liquid phase storage, samples are submerged directly in liquid nitrogen at -196 degrees Celsius. In vapour phase, samples are held above the liquid surface in nitrogen vapour at temperatures typically between -150 and -190 degrees Celsius depending on height within the vessel. The critical difference is contamination risk. Liquid nitrogen is not sterile, and in liquid phase storage any pathogen in the tank environment has direct contact with every stored sample. The HFEA Code of Practice increasingly reflects the expectation that vapour phase storage and closed carrier systems are the appropriate standard for licensed human reproductive material in the UK.
Manufacturers publish static hold time figures measured under controlled laboratory conditions: full vessel, sealed, upright, at approximately 20 degrees Celsius, with no access events. Functional hold time during a real transfer is lower because samples, access events, and handling all contribute heat load. A USPTO analysis of dry shipper engineering distinguishes explicitly between static and functional hold time. For clinical planning, hold time should be calculated against the maximum plausible journey time including delays, not the expected transit, and a meaningful safety margin should be built in above that figure.
Dry shipper prices in the UK market range from under £500 to over £3,000 for clinical-grade units. The variation reflects differences in hold time, absorbent material performance, canister configuration, construction quality, and IATA compliance certification. A comprehensive analysis of ISO 21973 GMP-grade cryogenic transport requirements confirms that not all vessels meeting the basic regulatory threshold deliver equivalent performance under real transit conditions. For reproductive medicine applications, the relevant comparison is not purchase price but cost per successful transfer, which includes the probability that the vessel maintains cryogenic conditions throughout a delayed or mishandled journey.
Bull semen is stored in plastic straws, usually 0.25ml, held in goblets on aluminium canes inside the canisters of a liquid nitrogen semen tank at -196 degrees Celsius. The tank is a vacuum-insulated dewar that holds temperature for weeks between nitrogen top-ups, and straws remain viable indefinitely while submerged. The practical risks are a tank running dry between deliveries and straws being warmed during retrieval, which is why nitrogen level checks and fast, low retrieval technique are standard practice. Cryolab’s semen storage tank guide covers tank selection for AI programmes.
Yes, provided it travels in a dry shipper. A dry shipper holds samples at approximately -190 degrees Celsius using nitrogen absorbed into its lining, with no free liquid present, which is what makes it unrestricted for air transport under IATA regulations. The consignment also needs the importing country’s health certification and complete straw identification. The shipper’s holding time must exceed the worst plausible journey, including customs delays, not just the scheduled transit. See Cryolab’s cryoshipper guide for holding time selection.
Indefinitely, as long as the tank holds temperature. At -196 degrees Celsius all biological activity stops, and calves have been produced from semen frozen decades earlier with no decline attributable to storage duration. What degrades samples is not time but temperature excursions: a tank running low on nitrogen, or straws repeatedly lifted into the warm neck during retrieval. Storage duration is a question of tank reliability, covered in Cryolab’s liquid nitrogen tank guide, not biology.
Freezing milt lets producers use their best males across multiple spawning seasons and sites, decouples egg production from the natural spawning window, and enables cross-fertilisation between broodstock held at different locations. It also underpins conservation gene banking: milt frozen before a river is treated for parasites allows the original genetic line to be restored afterwards. Milt is frozen in standard 0.25ml or 0.5ml straws and stored in liquid nitrogen vessels, with research showing it should be frozen soon after collection for best post-thaw fertility.
An AI tank, or semen storage tank, holds liquid nitrogen and is designed for static long-term storage on a farm or at an AI centre, with holding times measured in weeks. A dry shipper contains no free liquid nitrogen; its lining absorbs the nitrogen, creating a vapour environment safe for courier and air transport, with holding times measured in days. Samples live in the tank and travel in the shipper, and a shipper should never be used for ongoing storage. Cryolab’s semen storage tank and cryoshipper guides cover both.
Chilled semen is collected, extended and cooled for courier delivery, and must be inseminated within 24 to 72 hours of collection, so the stallion has to be available within a day or two of the mare’s cycle. Frozen semen is cryopreserved in 0.5ml straws and stored in a semen storage tank at -196 degrees Celsius, where it keeps for decades and can be shipped anywhere in a dry shipper well ahead of the season. The trade-off is at the mare’s end: chilled semen tolerates insemination around 24 to 48 hours before ovulation, while frozen semen must be timed within hours of ovulation, which demands intensive veterinary monitoring.
The accepted window runs from roughly 12 hours before ovulation to 6 hours after it, with the best results as close to ovulation as possible. Hitting it requires ultrasound scans as often as every six hours and usually an ovulation induction agent timed against follicle size, which is why frozen semen breeding is a veterinary exercise rather than a scheduling one. The Royal Veterinary College describes the monitoring regime in detail. The cold chain’s job is to make sure the dose is intact when that narrow window opens.
It varies by stallion and freezing centre. Equine semen is typically frozen in 0.5ml straws, and because post-thaw quality differs widely between stallions, centres define a dose by motile sperm numbers after thaw rather than by straw count, so one insemination dose is commonly several straws. The dose definition issued by the freezing centre is part of the dose: thawing fewer straws than it specifies under-doses the mare and wastes the attempt. Store the definition with the inventory record for the storage tank, not in an email thread.
Yes, and it routinely is. Frozen doses travel in a dry shipper, a vapour phase vessel with no free liquid nitrogen on board, which is why it moves unrestricted by air and road carriers. International consignments need export health certification and straw identification matching the paperwork, and the sensible pattern is to ship well ahead of the breeding season into the destination’s own storage tank, so a customs delay costs patience rather than a breeding. Shipping against a mare’s cycle is possible but leaves no margin if the consignment is delayed.
Decades. At -196 degrees Celsius biological activity effectively stops, and properly frozen semen held continuously in liquid nitrogen remains usable for the life of the storage arrangement, including after the stallion’s death. The qualifier is continuity: storage life assumes the straws stay below the frost line of a correctly maintained liquid nitrogen vessel with a disciplined fill schedule. Every warming excursion during a careless retrieval spends some of the sample’s quality, and those losses accumulate silently across years of storage.
Because one litre of liquid nitrogen becomes roughly 680 litres of nitrogen gas at room temperature, and that gas displaces oxygen without any smell or warning. In a small store room, cellar, lift or vehicle, a spill or heavy boil-off can push the oxygen concentration below survivable levels in minutes, and the body gives no alarm because it senses rising carbon dioxide rather than falling oxygen. This is why most liquid nitrogen fatalities happen in confined spaces, why storage rooms need ventilation assessments and oxygen depletion monitors, and why nobody ever rides a lift with a charged dewar. Our guide to liquid nitrogen hazards covers the full picture.
Not by burning, because nitrogen is inert and non-flammable, but by pressure. Sealed into a closed container, the 1 to 680 litre liquid-to-gas expansion has nowhere to go and the container eventually ruptures violently. This is why every proper liquid nitrogen vessel has a loose-fitting lid or pressure relief, why an iced-up neck plug needs clearing immediately, and why liquid nitrogen must never be carried in a sealed household flask. The other explosive risk is indirect: oxygen condensing on very cold surfaces creates oxygen-enriched liquid that makes surrounding materials burn fiercely.
A brief splash across open skin often skitters off on a cushion of its own vapour, which is why small splashes sometimes do little harm. Sustained contact is different: liquid trapped against the skin by a glove cuff, a shoe or clothing, or contact with metal chilled to -196 degrees Celsius, freezes tissue within seconds and causes cold burns and frostbite. That is why cryogenic handling guidance specifies loose-fitting cryogenic gloves that can be flung off, trousers worn over footwear, and a face shield when decanting. Treat affected skin with copious lukewarm water, never hot, and seek medical attention for anything beyond a minor mark.
Standard practice across UK laboratories and hospitals sets the first oxygen depletion alarm at 19.5 percent, against the 20.9 percent oxygen of normal air. Impairment begins well before the air feels any different: concentrations in the mid teens degrade judgement and coordination, and below about 10 percent unconsciousness can arrive in minutes with no sensation of breathlessness. Monitors belong in any room where the stored nitrogen volume could realistically depress oxygen below the alarm point if released, with the readout visible from outside the door so staff are warned before entering rather than after.
Short answer: move the cold, not the liquid, whenever possible. For samples, a dry shipper holds cryogenic temperature with no free liquid nitrogen on board, which makes it safe for vehicles and unrestricted for air freight. Where liquid itself must move, use a purpose-built transport dewar with a vented closure, secure it upright, never carry it in the passenger compartment of a vehicle, and never ride in a lift with it; the vessel travels alone and is met on the destination floor. Windows open and journeys short is the rule for any road movement of liquid.
