Low Temperature Liquified Gases - CryogenicsVarious low temperature liquefied atmospheric gases including liquid nitrogen, oxygen, argon, helium and carbon dioxide are stored and used within University premises. There are significant hazards associated with these gases which relate to their physical properties.
Action by Heads
Heads should ensure that formal risk assessments are carried out of all work activity involving the use low temperature liquefied gases or systems using such gases. Heads should also ensure that all people who work with such gases are provided with adequate instruction and practical training in the means by which such risks can be minimised and the actions to be taken in an emergency. These are:
- Asphyxiation in oxygen deficient atmospheres;
- Fire in oxygen enriched atmospheres;
- Cold Burns, frostbite and hypothermia from the intense cold;
- Over pressurisation from the large volume expansion of the liquid.
Note: Special attention should be drawn to the insidious nature of the risks due to the rapidity of effects coupled with the fact that an operator may be completely unaware that a hazardous condition has developed.
Oxygen Deficiency Monitoring
The following points should be taken into account:
- Standard Operating Procedures should not only specify what a member of staff should do, but be explicit about what they should not.
- Management should check, on a regular basis, that staff are following procedures.
- Staff should be trained and full documentation kept of that training.
- Oxygen sensors, connected to alarm systems, should be carefully sited to ensure that they are not susceptible to localised pockets of nitrogen and hence sound the alarm inappropriately.
- Oxygen level alarms should:
- sound both inside the nitrogen dispensing facility and outside;
- be interlocked to a fail-safe valve that shuts off the gas supply when the alarm sounds.
- Design of liquid nitrogen facilities should follow the British Compressed Gases Association Code of Practice CP21.
Care With Cryogenics - The Use of Low Temperature Liquefied Gases (BOC Gases)