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- Risk of asphyxiation and loss of consciousness. An atmosphere with less than 16% oxygen is hazardous
(nitrogen gas displaces oxygen in the air).
- Nitrogen gas builds up in low areas.
- Risk of frostbite.
- Risk of corrosion of steels in the presence of humidity.
- In closed vessels, the pressure can reach very high values (in the order of 700 bar) resulting in a risk of bursting.
Critical precautions to be taken:
- Areas where liquid nitrogen is stored or used must be well ventilated (extraction or ventilation at both high and
low levels in the room).
- Areas liable to contain an unbreathable atmosphere must be indicated with an asphyxiation hazard pictogram.
- Never enter a room that has contained liquid nitrogen without taking predefined precautionary measures.
- Eliminate links between areas where liquid nitrogen is stored or used and low points (pits, drainage channels,
basements) where it could accumulate and render the atmosphere unbreathable.
- Use an O
2
concentration detector to ensure that the oxygen concentration is greater than 18%.
- Avoid uninsulated liquid nitrogen pipes in any areas.
- Call on the services of a specialist to determine the layout of facilities.
In case of an incident or accident:
- If asphyxiation has occurred:
- Check the oxygen concentration in the room and then take the victim to the open air (taking an
insufflator with you).
- Start artificial respiration and call the emergency services.
- In the event of a leak:
- Evacuate the room.
- Do not enter the room without breathing apparatus if the oxygen concentration is lower than 18%.
- Close the valve on the leaking outlet.
- Aerate the room at length, ensuring that low points are ventilated.
- If liquid nitrogen is splashed:
- In the eyes: rinse the eye thoroughly for at least 20 minutes. Call a doctor.
- On the skin: do not rub. Remove clothing if necessary. Warm up the affected areas as quickly as
possible under running water for 20 minutes. Call a doctor.
2)
Precautions regarding equipment
Warning: nitrogen is liquid at extremely low temperatures and is stored in a double-walled tank. A high vacuum between
the walls ensures good thermal insulation. This equipment, especially mobile storage tanks, must be handled with care.
- Avoid impacts. Never lay a cryogenic container on its side.
- Do not expose containers to excessive temperatures.
- Treat valves with care (operate gently, do not dismantle or lubricate valves).
- All equipment used must be in good condition and designed for use at the intended temperature and pressure.
- Mobile equipment must be sheltered from inclement weather. Open-necked containers must be fitted with
stoppers to avoid the neck becoming blocked by cryopumping of ambient humidity.
- Use suitable connection hoses; never use intermediate couplings.
- Monitor the pressure of closed containers and check safety equipment (pressure relief valve).
- Regulations apply to the transportation of recipients.
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