Handling Liquid Nitrogen - Thermo Scientific CRYO Plus 1 Operating And Maintenance Manual

Thermo Scientific

Handling Liquid Nitrogen

Warning Contact of liquid nitrogen or cold gas with the skin or eyes may
cause serious freezing (frostbite) injury.
Handle liquid nitrogen carefully.
The extremely low temperature can freeze human flesh very rapidly.
When spilled on a surface, the liquid tends to cover it completely and
intimately, cooling a large area. The gas issuing from the liquid is also
extremely cold. Delicate tissue, such as that of the eyes, can be damaged
by an exposure to the cold gas which would be too brief to affect the
skin of the hands or face.
Never allow any unprotected part of your body to touch objects cooled by
liquid nitrogen.
Such objects may stick fast to the skin and tear the flesh when you
attempt to free yourself. Use tongs to withdraw objects immersed in the
liquid, and handle the object carefully.
Wear protective clothing.
Protect your eyes with a face shield or safety goggles (safety glasses with-
out side shields do not give adequate protection). Always wear gloves
when handling anything that is, or may have been, in immediate contact
with liquid nitrogen. Insulated gloves are recommended, but heavy
leather gloves may also be used. The gloves should fit loosely, so that
they can be thrown off quickly if liquid should splash into them. When
handling liquid in open containers, it is advisable to wear high-top
shoes. Trousers (which should be cuffless if possible) should be worn
outside the shoes.
Introduction
The safe handling and use of liquid nitrogen in cryogenic refrigerators and
dewar flasks is largely a matter of knowing the potential hazards and using
common-sense procedures based on that knowledge. There are two
important properties of liquid nitrogen that present potential hazards:
1. It is extremely cold. At atmospheric pressure, liquid nitrogen boils at -
320° F (-196° C).
2. Very small amounts of liquid vaporize into large amounts of gas. One
liter of liquid nitrogen becomes 24.6 cu. ft. (0.7 m3) of gas.
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7007400 Cryoplus 7007400 Cryoplus
Section 9
Appendix
9-1 9-1