A dry shipper is a purpose-designed cryogenic transport vessel that maintains sample temperatures below minus 150 degrees Celsius without containing any free liquid nitrogen. This is what makes it practical for transport, distinguishing it from standard liquid nitrogen dewars.
The mechanism relies on an absorbent material, usually a porous aluminium matrix, built into the inner walls of the vessel. Before use, the dry shipper is charged by pouring liquid nitrogen into it and allowing the absorbent material to soak it up fully. Once charged, the excess free liquid is poured out, leaving nitrogen absorbed in the matrix. This absorbed nitrogen evaporates slowly during transport, maintaining the internal temperature at cryogenic levels.
The absence of free liquid nitrogen means the vessel can be transported without the hazardous materials classifications that apply to containers with free cryogenic liquids. This makes road courier transport practical and straightforward.
The key performance specification for a dry shipper is its static hold time, meaning how many hours it can maintain its target temperature after charging. Different models have different hold times, typically ranging from 24 hours for basic units to over 72 hours for premium models.
For UK domestic embryo transport, where journey times are typically under 12 hours, most dry shippers provide a very substantial safety margin. All shipments should include a temperature logging device inside the package.
Cryolab supplies vapour-phase dry shippers for UK IVF embryo and gamete transport. Visit cryolab.co.uk“>Cryolab
