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Cryogenic Liquids
A cryogenic liquid is defined as a liquid with a normal boiling point below
-150 C (123°K, -240°F). The most commonly used industrial gases that
are transported, handled, and stored in the liquid state at cryogenic temperatures
are hydrogen, helium, nitrogen, oxygen, and argon. There are a number of general
precautions and safe practices that must be observed because of the extremely
low temperatures and high rates of conversion into gas of all the cryogenic
liquids. There are also specific precautions that must be followed where a
particular liquid may react with contaminants or may present other hazards
associated with that particular product such as asphyxiation or flammability.
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Boiling Point @ 1 atm |
Freezing Point @ 1 atm |
Density, Liquid, 1 atm |
Density, Gas, 1 atm |
Expansion Ratio,
Liquid to Gas, 20 C |
| Hydrogen |
-252.8 C, 20 K, -423.0 F |
-259.2 C, 14 K, -434.5 F |
4.23 lb / scf |
0.005229 lb / scf |
1 : 848 |
| Helium |
-268.9 C, 4 K, -452.1 F |
-272.2 C, 0 K, -459.7 F |
7.798 lb / scf |
0.0103 lb / scf |
1 : 754 |
| Nitrogen |
-195.8 C, 77 K, -320.5 F |
-210.0 C, 63 K, -346.0 F |
71.23 lb / scf |
0.0831 lb / scf |
1 : 694 |
| Oxygen |
-183.0 C, 90 K, -297.4 F |
-218.8 C, 54 K, -361.9 F |
50.45 lb / scf |
0.0725 lb / scf |
1 : 860 |
| Argon |
-185.9 C, 87 K, -302.6 F |
-189.4 C, 85 K, -308.8 F |
87.40 lb / scf |
0.1034 lb / scf |
1 : 840 |
As always, end users should have and be thoroughly familiar with the Material
Safety Data Sheet (MSDS) for their specific product. All operators must be
familiar with the instructions provided with the equipment to be used with
the cryogenic liquid.
First Aid
For skin contact with cryogenic liquid nitrogen, remove any clothing that
may restrict circulation to the frozen area. Do not rub frozen parts, as tissue
damage may result. As soon as practical, place the affected area in a warm
water bath that has a temperature not in excess of 105°F (40°C). Never
use dry heat. Call a physician as soon as possible.
Frozen tissue is painless and appears waxy with a possible yellow color. It
will become swollen, painful, and prone to infection when thawed. If the frozen
part of the body has been thawed, cover the area with a dry sterile dressing
with a large bulky protective covering, pending medical care. In the case of
massive exposure, remove clothing while showering the victim with warm water.
Call a physician immediately.
If the eyes are exposed to the extreme cold of the liquid nitrogen or its
vapors, immediately warm the frostbite area with warm water not exceeding 105°F
(40°C) and seek immediate medical attention.
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