A liquid nitrogen dewar is a vacuum-insulated vessel designed to store or dispense liquid nitrogen at its boiling point of minus 195.8 degrees Celsius. The term originates from the Scottish physicist Sir James Dewar, who invented the vacuum flask in 1892. In laboratory and clinical settings, liquid nitrogen dewars range from small 1 to 5 litre bench-top vessels used for short-term sample handling to large 50 to 500 litre static storage vessels used as primary repositories for biological material in IVF clinics, sperm banks, and biobanks.
A cryogenic storage tank differs from a standard laboratory dewar primarily in its engineering specification, intended duration of use, and internal organisation capability. Clinical cryogenic storage tanks are designed for long-term unattended storage with low daily liquid nitrogen evaporation rates, typically between 0.1 and 0.5 litres per day depending on capacity, and accept internal racking, canister, and goblet systems to organise and identify individual samples. They incorporate vacuum-jacketed double-wall stainless steel construction with multilayer superinsulation, and many are fitted with liquid nitrogen level sensors compatible with continuous remote monitoring systems.
A standard laboratory liquid nitrogen dewar used for dispensing or short-term cooling is not a substitute for a purpose-built cryogenic storage tank in a licensed clinical environment. Cryolab supplies both working dewars and long-term clinical storage tanks including the CryoNest range, full details of which are available at cryolab.co.uk/storage-vessels/.
