A liquid nitrogen dewar is a vacuum-insulated vessel designed to store liquid nitrogen at -195.8 degrees C for extended periods. In IVF laboratories, dewars are used as primary long-term storage vessels for frozen biological samples, and as working vessels for holding liquid nitrogen used during vitrification and dry shipper charging.
The defining characteristic of a storage dewar is that it contains free liquid nitrogen. Samples stored within it are either immersed in the liquid phase or suspended in the vapour phase above it. The vacuum insulation maintains temperature with minimal evaporation over weeks or months depending on vessel specification.
How a Dry Shipper Differs
A dry shipper is a transport vessel that uses liquid nitrogen differently. Rather than holding free liquid nitrogen, a dry shipper contains an absorbent inner matrix that is charged with liquid nitrogen and retains the cold within the material itself. Once charged, the vessel contains no free liquid nitrogen – which is what allows it to travel as not restricted under IATA Special Provision A152 and makes it suitable for courier use. 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.
A dewar holds liquid nitrogen and is used for storage or as a working supply. A dry shipper holds the cold from liquid nitrogen without holding the liquid itself, and is used for transport. The two are not interchangeable for their respective purposes.
Cryolab supplies both the CryoNest series storage vessels and the full CryoStork dry shipper range (V2, V3, V4, V6 and V10). For help choosing the right vessel for your application, use CryoGPT or contact us.
