When air warms, it vaporizes and can rip off insulation with explosive force. Cryogenic fluids with a boiling point below that of liquid oxygen, including liquid nitrogen, may condense oxygen from the air if exposed to the atmosphere. Because oxygen does not evaporate as rapidly as liquid nitrogen, it will accumulate and may cause violent reactions with incompatible materials in the system. Potential for damaging living tissue. Burns to the skin can result from direct contact with a cryogen, uninsulated piping, or equipment containing a cryogen.
Permanent damage can occur if liquid cryogen comes into contact with the eye.
Preventing System Overpressure. Thus, the suitability of materials must be carefully investigated before using them for cryogenic work. Frangible disks are also recommended when the capacity of the operational relief device is not adequate to take care of unusual or accidental conditions. This is especially true when insulation of the system is dependent upon maintaining a vacuum in any part of the system, including permanently sealed dewars. A relief device must be capable of handling the maximum volume of gas that could be produced under the most adverse condition.