Choosing the right liquid nitrogen dewar is one of the most consequential purchasing decisions a laboratory manager or IVF clinic coordinator will make. Get it right and your samples are protected, your team works safely, and your LN2 costs stay manageable. Get it wrong and you are dealing with frequent refills, inadequate storage capacity, or worse -compromised samples.

This guide focuses on 20 litre liquid nitrogen dewars -one of the most widely used vessel sizes in clinical and research settings -covering everything from how they work and who needs one, to how to choose between models and what to look for in a supplier.

What Is a 20 Litre Liquid Nitrogen Dewar?

A liquid nitrogen dewar is a vacuum-insulated vessel designed to store and dispense liquid nitrogen at -196°C. The double-walled vacuum construction minimises heat transfer, slowing the rate at which LN2 evaporates and extending the time between refills.

A 20 litre dewar sits in the mid-range of laboratory vessel sizes -large enough to serve as a meaningful working stock for a busy laboratory, compact and light enough to be handled safely by a single person without mechanical assistance. This combination makes it one of the most practical vessel sizes for day-to-day laboratory use across IVF clinics, andrology units, research facilities and hospital laboratories.

At -196°C, liquid nitrogen occupies approximately 1.4 litres of liquid per kilogram of nitrogen. A 20 litre vessel therefore holds a meaningful reserve -sufficient for topping up storage tanks, preparing samples for cryopreservation, and day-to-day laboratory handling without requiring constant resupply.

Why Liquid Nitrogen Storage Matters in IVF

The scale of fertility treatment in the United Kingdom makes reliable cryogenic storage infrastructure a clinical necessity, not an optional extra. According to the Human Fertilisation and Embryology Authority, more than 50,000 IVF cycles are performed in the UK each year, with frozen embryo transfers now accounting for a growing proportion of successful pregnancies.

The HFEA’s own data consistently shows that frozen embryo transfer cycles have improved significantly in success rates over the past decade, with vitrification -which depends entirely on reliable liquid nitrogen storage -now the dominant cryopreservation method in accredited UK clinics.

This context matters when choosing a dewar. A 20-litre liquid nitrogen vessel used for working stock in an IVF clinic is part of a clinical care chain. Choosing a vessel with adequate insulation, reliable construction and appropriate capacity is not a procurement decision -it is a patient safety decision.

Who Uses 20 Litre Liquid Nitrogen Dewars?

The 20 litre dewar is one of the most versatile vessel sizes in laboratory use. It serves different functions across different settings:

• IVF clinics and fertility laboratories use 20 litre dewars as working stock vessels -kept topped up and used daily for adding liquid nitrogen to long-term storage tanks, preparing samples for vitrification, and general laboratory LN2 handling.
• Andrology units and sperm banks use 20 litre vessels for working stock and short-term sample storage during processing and preparation before transfer to long-term storage.
• Hospital and NHS laboratories use smaller dewars for cryosectioning, tissue preservation, and biological sample handling across a range of clinical applications.
• Research institutions and universities use 20 litre dewars across life science departments for cell culture work, biological sample preservation, and any application requiring a reliable LN2 supply at bench level.

20 Litre Dewar vs Larger Storage Vessels -Understanding the Difference

A 20 litre dewar is primarily a working vessel. It is not the right choice for long-term biological sample storage at scale -that is what larger cryogenic storage vessels are designed for.

Working vessels like a 20 litre dewar are designed for frequent handling, daily use, and regular LN2 dispensing. They are optimised for convenience and practicality -easy to carry, easy to pour from, and sized appropriately for daily operations.

Long-term storage vessels are designed to hold biological samples -embryos, gametes, sperm, tissue -for months or years at stable cryogenic temperatures with minimal LN2 consumption. These require higher insulation efficiency, secure sample organisation systems, and larger capacities.

Cryolab’s storage vessel ranges serve both needs. The CryoCan series -available in 30-6, 47-6 and 47-10 configurations -provides compact, reliable cryogenic storage for smaller laboratories and clinics. The CryoNest® series -including the XL, XXL and XXXL models -provides high-capacity storage for larger IVF units and biobanks, with the CryoNest® XL offering 95 litres of storage capacity without increasing laboratory footprint.

What to Look for When Buying a 20 Litre Liquid Nitrogen Dewar

Not all 20 litre dewars are built to the same standard. Here is what matters:

• Static storage time -how long the vessel holds LN2 before evaporation. A well-insulated 20 litre dewar should achieve at least 60 days static storage time.
• Neck diameter -wider neck makes daily dispensing easier. Narrower neck reduces evaporation. For working stock use, a wider neck is generally more practical.
• Construction quality -look for aluminium or stainless steel outer construction, robust handles rated for the full weight when filled, and a secure neck plug.
• Weight when full -liquid nitrogen weighs approximately 0.8 kg per litre. A 20 litre vessel when full is approximately 19-21 kg total -within safe single-person handling limits for most staff.

CryoCan Series -Compact Liquid Nitrogen Storage

Cryolab’s CryoCan range offers reliable cryogenic storage in a compact, practical format suited to smaller laboratories, satellite clinics and settings where space is at a premium.

• CryoCan 30-6 -30 litres of storage capacity with 6 canisters. A practical choice for smaller IVF units or andrology laboratories with moderate sample volumes.
• CryoCan 47-6 -47 litres with 6 canisters. A meaningful step up in storage capacity whilst remaining manageable in size.
• CryoCan 47-10 -47 litres with 10 canisters. Significantly greater sample organisation capacity for busy laboratories storing large numbers of individual patient samples.

View the full CryoCan range

CryoNest® Series – High Capacity Cryogenic Storage

For IVF clinics, fertility centres and biobanks with higher sample volumes, the CryoNest® series offers a step change in storage capacity and efficiency.

• CryoNest® XL -95 litres of cryogenic storage capacity. Significantly more than a standard 47-litre tank without increasing laboratory footprint. Ideal for busy IVF clinics storing embryos, oocytes and sperm across a large patient population.
• CryoNest® XXL and XXXL -even greater capacity for large fertility centres, biobanks and research institutions where sample volumes demand maximum storage efficiency.

View the full CryoNest® range

Safe Handling of Liquid Nitrogen Dewars

Liquid nitrogen presents real safety risks if handled incorrectly. The Health and Safety Executive provide clear guidance on LN2 handling in laboratory environments, and all laboratory staff working with cryogenic vessels should be trained and competent before use.

• Always wear cryogenic gloves rated for LN2 exposure, a full face shield, and a laboratory coat or cryogenic apron.
• Work in a well-ventilated area. Liquid nitrogen evaporates to nitrogen gas which displaces oxygen -the HSE recommends oxygen depletion monitoring in any area where LN2 is regularly handled.
• Never seal a dewar airtight. Always use appropriate loose-fitting stoppers or vented caps.
• Transport carefully using a trolley where possible. Never drag or tip a filled vessel.
• Always store dewars in an upright position to prevent spillage and maintain vacuum insulation integrity.

Frequently Asked Questions

How long does a 20 litre liquid nitrogen dewar last before needing a refill?

Static storage time depends on insulation quality and how frequently the vessel is opened. A well-insulated 20 litre dewar should hold LN2 for 60 days or more under static conditions. For vessels used daily as working stock, expect to refill every 3-6 weeks depending on usage volume.

Can a 20 litre dewar be used for long-term embryo or sperm storage?

A standard 20 litre working dewar is not designed for long-term biological sample storage. For storing embryos, oocytes or sperm, a dedicated cryogenic storage vessel with appropriate canister systems -such as the CryoCan or CryoNest® series -is required.

What is the difference between the CryoCan and CryoNest® ranges?

The CryoCan series offers compact, reliable cryogenic storage in 30 and 47 litre capacities -suited to smaller laboratories and clinics with moderate sample volumes. The CryoNest® series offers significantly higher capacity, with the XL model providing 95 litres of storage, making it the right choice for busy IVF clinics, large fertility centres and biobanks.

What PPE do I need to handle a liquid nitrogen dewar safely?

As a minimum: cryogenic gloves rated for LN2 exposure, a full face shield, and a laboratory coat or cryogenic apron. The HSE recommends oxygen monitoring in areas where LN2 is regularly used. All staff should be trained in cryogenic safety before handling liquid nitrogen vessels.

Does Cryolab supply liquid nitrogen dewars worldwide?

Yes. Cryolab supplies the full CryoCan and CryoNest® ranges to IVF clinics, research laboratories, hospitals and biobanks worldwide. Contact us through the website for pricing and delivery information.