Cryogenic liquid containers, also referred to as liquid cylinders, are double-walled vacuum vessels with multilayer insulation in the annular space.

They are designed for the reliable and economic transportation and storage of liquefied gases at cryogenic temperatures, typically colder than –130°F (–90°C).

Cryogenic liquid containers  are open, non – pressurized vessels for holding cryogenic liquids.

The cryogenic containers normally found in liquid containers are liquid nitrogen (LIN), liquid argon (LAR), liquid oxygen (LOX), and liquid helium (LHE).

Carbon dioxide and nitrous oxide are also available as refrigerated liquids in similar containers.

Although these cryogenic containers are well insulated, heat will continuously leak into the product, due to the extremely large temperature difference between the cryogenic liquid and the ambient environment. The heat leak will cause some vaporization to occur.

Vaporized product, if not used, will collect in the vapor space above the liquid and build pressure.

This is referred to as head pressure. The head pressure will build in the cryogenic container and periodically vent via the pressure
relief valve. Vaporization rates will vary and may be as low as 0.4% or as high as 3% of the container’s volume per day.
This is a normal and safe function of the container.
The user of any cryogenic liquid container should be thoroughly familiar with the product and the mechanical working’s of the container before using the product