Freezers, Blood Bank, Cryogenic, Vapor Phase Nitrogen
Definition : Blood bank cryogenic freezers designed to store blood bank products and samples using liquid nitrogen as the cooling agent and vapor phase nitrogen for storage. Vapor phase nitrogen storage provides a temperature of -140 degrees Celsius (-220 degrees Fahrenheit) that is not as low as the liquid nitrogen (-180 degrees Celsius [-292 degrees Fahrenheit]), but decreases the risk of cross-contamination between stored products compared to the use of liquid nitrogen immersion. These freezers typically consist of a chamber with two vessels separated by a vacuum space (the inner vessel is for the cryogenic fluid, and the outer vessel intended to insulate the cryogenic liquid from the environment); automatic level and cryogenic temperature controls; an external container to replenish the cryogenic fluid; a pressure-relief device; and a pressure-controlling valve. Red blood cells (RBCs) are immersed using appropriate containers in the vapor atmosphere above the liquid nitrogen. Cryogenic blood bank freezers are used mainly to store rare types of RBCs with a cryoprotective agent such as glycerol at 40 percent or dimethyl sulfoxide for long periods, typically up to several years.
Entry Terms : "Vapor Phase Nitrogen Cryogenic Freezers"
UMDC code : 22052