A liquid nitrogen dry shipper maintains an internal temperature between -150 and -190 degrees C during transport by releasing nitrogen vapour from an absorbent core material, with no free liquid present inside the vessel. This design is what allows the shipper itself to travel as not restricted under IATA Special Provision A152, and what makes it the only acceptable cryogenic transport vessel for vitrified embryos and sperm samples moving between locations.
What is inside a liquid nitrogen dry shipper that absorbs the LN2?
The absorbent core is typically a porous silica or zeolite-based material engineered to retain liquid nitrogen under a wide range of orientations and conditions. The material has a high surface area that allows it to absorb and hold several litres of LN2 while presenting no free liquid at the vessel opening. When the vessel warms slightly during transport, the nitrogen evaporates from the sorbent and maintains the cold environment inside the sample cavity.
How do you know a dry shipper is correctly charged?
After the initial fill and soak period, tip the vessel gently. If liquid pours out, return it upright and wait another 30 to 60 minutes before testing again. A correctly charged dry shipper produces no free liquid flow when tipped. You should still hear or feel a small amount of vapour exiting through the vent – that is normal and indicates the vessel is venting pressure safely.
What sample loads can a liquid nitrogen dry shipper carry?
This depends on the vessel’s inner cavity dimensions and the cane or rack system used. A 3-litre dry shipper typically accommodates one to three cryogenic canes. A 10-litre model may hold six or more. For large transfers involving multiple patients, it is worth calculating the number of canes required before selecting the vessel size, rather than after.
The single most important step in dry shipper use is the charging process. Samples placed in an undercharged vessel may appear safe during short journeys but can warm to damaging temperatures on longer routes or with unexpected delays.
Browse the CryoStork dry shipper range or get in touch with the Cryolab team.
