Liquid Nitrogen Safety
Properties of Liquid Nitrogen (LN2)
- It is extremely cold: 77.3K = -196C = -320F at atmospheric pressure. This can cause severe frost bite.
- On vaporization it expands by a factor of 700; one liter of liquid nitrogen
becomes 24.6 cubic feet of nitrogen gas. This can cause explosion of a sealed container, or it can displace oxygen in the room and cause suffocation without warning.
- It can become oxygen enriched and cause ordinarily noncombustible materials to burn rapidly.
Precautions when handling liquid nitrogen
- Treat liquid nitrogen and any object cooled with liquid nitrogen
- Take care not to allow liquid nitrogen to be trapped in clothing near
- Wear safety glasses or a face shield when transfering liquid nitrogen.
- Wear gloves when touching any object cooled by liquid nitrogen.
Gloves should be loose fitting, so they could be thrown off if liquid were to
pour inside them
- Use only approved unsealed containers. Never pour it into a coffee
thermos. Never seal it in any container (it will explode).
- Never dip a hollow tube into liquid nitrogen; it may spurt liquid.
- Never use in a small poorly ventilated room,
and never dispose of liquid nitrogen by pouring it on the floor.
It could displace enough oxygen to cause suffocation.
Nitrogen gas is colorless and odorless--the cloud that forms when you pour
liquid nitrogen is condensed water vapor from the air, not nitrogen gas.
- Do not store liquid nitrogen for long periods in an uncovered
container (on the other hand, never totally seal a container). Because the
boiling point of oxygen, 90.1K, is above that of nitrogen, oxygen can
condense from the air into the liquid nitrogen. If the air over the nitrogen
circulates, this liquid oxygen can build
up to levels which may cause violent reactions with organic materials; even
materials which are ordinarily nonflammable.
For example, a severe clothing fire could result from ignition in the presence of liquid oxygen.
The above is first aid information is from the publication
"Handle With Care", C 1996 Harsco Corporation, Factory code 7950-8052.
- Suffocation: If person seems to become dizzy or looses conciousness
while working with liquid nitrogen, move to a well-ventilated area
immediately. If breathing has stopped, apply artificial respiration.
If breathing is difficult, give oxygen. Call a physician. Keep warm and
- Frost bite: If exposed to liquid or cold gas, restore tissue to normal
body temperature, 98.6F (37C), followed
by protection of the injured tissue from further damage and infection.
Remove or loosen clothing that may constrict blood circulation to
the frozen area. Call a physician. Rapid warming of the affected part is
best achieved by using water at 106F (42C). Under no circumstances should the water be over 112F (44C), nor should the frozen part be rubbed either before or
after rewarming. The patient should neither smoke, nor drink alcohol.
How to Suffocate in a Cold Room