If you work in a fertility clinic, a veterinary reproduction centre, a biobank, or a research laboratory, at some point you will need to choose between a dry shipper and a standard liquid nitrogen dewar. Both vessels store and protect cryopreserved biological samples at ultra-low temperatures. But they are designed for fundamentally different purposes, and using the wrong one for the job creates unnecessary risk and cost.
A standard liquid nitrogen dewar is designed for long-term static storage. It holds liquid nitrogen in a free pool within a vacuum-jacketed inner vessel. Samples are stored either submerged in the liquid or in the vapour space just above it. The dewar is filled periodically as nitrogen evaporates, and with a high-quality vacuum jacket and a low evaporation rate, a well-specified storage dewar can hold a very large number of samples safely for years. Standard dewars are the right choice for a clinic or laboratory storage room, where samples will remain in one place and be accessed periodically.
A dry shipper is designed for transport. Its defining feature is that it contains no free liquid nitrogen, which means it can be safely moved, tilted, carried, couriered, and in many cases air freighted without the spill risk and transport restrictions associated with free cryogenic liquid. The trade-off is that a dry shipper has a finite hold time, typically 24 to 72 hours depending on the model, after which it will need recharging.
The practical rule is simple. If samples are staying in one place, use a storage dewar. If samples need to move, use a dry shipper.
There are some nuances worth understanding:
Working dewars in a laboratory setting are small liquid nitrogen vessels used during procedures to keep samples cold while they are being handled. These are a third category, distinct from both long-term storage dewars and transport dry shippers.
For veterinary reproduction centres that both store and regularly transport semen, having both a long-term storage dewar and one or more dry shippers is standard practice. The storage dewar holds the collection. The dry shipper is charged when a shipment needs to go out.
For a fertility clinic arranging patient embryo transfers between licensed facilities, a dry shipper is the only appropriate transport vessel for regulatory and practical reasons.
For a research institution receiving cell line deliveries from a collaborating lab, a dry shipper sent with the samples is the standard method.
Ln2 dry shippers, as they are also commonly known, come in a range of sizes from compact 2-litre units ideal for single-patient clinical transport to 10-litre units suitable for high-volume veterinary or research shipments.
Cryolab stocks the full CryoStork range of dry shippers for every application, from compact clinical units to large-capacity research shippers.
