Cryogenics

Hazard Description
 

A gas is defined as cryogenic if it can be liquified at or below 123 K at atmospheric conditions. The unit measurement for the temperature of cryogenics is Kelvin (0K = -273 C).

A cryogenic gas has no colour and no odour, so it is very difficult to detect its presence (human senses do not warn!).

At CERN, the most commonly used cryogenic fluids are helium, argon and nitrogen:

Helium: is lighter than air (up) – at atmospheric pressure, it becomes liquid at temperatures lower than 4K.

Argon: it is heavier than air (down) – at atmospheric pressure, it becomes liquid at 87K.

Nitrogen: if cold, it is heavier than air (down) – at atmospheric pressure, it becomes liquid at 77K.

The main cryogenic hazards are:

  • Cold surfaces and vapor;
  • Oxygen Deficiency Hazard - ODH;
  • Pressure release.

ODH is particularly dangerous, if we consider that one litre of cryogenic fluid expands to ~700 litres (0.7 m3) of gas at ambient temperature. The presence of these gas in the air decreases the amount of oxygen.

cryo1

cryo2


CERN Safety Rules
 

The CERN safety documents concerning the cryogenic hazards are the following

Training Courses
 

On the CERN Learning Hub, it is possible to increase the awareness of the cryogenic hazards by following the trainings:

  • Cryogenic Safety – Awareness (online)
  • Cryogenic Safety – Fundamentals (classroom)
  • Cryogenic Safety – Helium Transfer (classroom)

The classroom trainings should be followed up by people working with cryogenic liquids.
 

Contact
 

For further information about the cryogenic hazard, please contact: