A dry shipper and a storage dewar both maintain cryogenic temperatures using liquid nitrogen, but they are designed for fundamentally different purposes. A storage dewar holds free liquid nitrogen and is used for static laboratory storage. A dry shipper contains no free liquid – the LN2 is absorbed into a porous sorbent – making it the correct vessel for transporting biological samples by road, rail, or air.

Why can you not use a standard dewar for air transport?

IATA regulations classify free liquid nitrogen as a dangerous good requiring specific documentation, labelling, and handling. A standard storage dewar with free LN2 present cannot be loaded onto a passenger aircraft and faces significant restrictions even on cargo flights. A dry shipper, with its absorbed LN2 and no free liquid, is classified differently and is accepted on passenger and cargo aircraft as not restricted under IATA Special Provision A152 when correctly prepared, labelled and annotated on the air waybill. Packing Instruction 650 is a separate requirement covering the biological samples inside where those are classified as UN 3373 Category B, not the nitrogen holding them cold.

Does a dry shipper maintain the same temperature as a storage dewar?

The interior temperature of a correctly charged dry shipper sits in the vapour phase of liquid nitrogen, typically between -150 and -190 degrees C depending on sample position within the vessel. This is sufficient to maintain biological samples in a fully cryopreserved state. Samples stored in the liquid phase in a standard dewar are held at -195.8 degrees C, but the temperature difference between liquid and vapour phase storage has no meaningful impact on sample viability for the durations involved in transport.

When should a lab use a dry shipper rather than a dewar?

Any time samples are leaving the laboratory building, a dry shipper is the appropriate vessel. This applies to transfers between clinics, patient sample collections from satellite locations, transport to genetics laboratories for PGT analysis, and shipments to international fertility banks.

One of the most frequent errors we see is labs using a standard storage dewar for inter-clinic transfers and assuming the journey time is short enough to be safe. A dry shipper exists precisely to eliminate that assumption.

Browse the CryoStork dry shipper range or speak to the Cryolab team about the right vessel for your transfer routes.