Accessibility statement

Storage & use

General

Ventilation is the key issue. Large scale vacuum insulated tanks are normally stored outside buildings because of the quantities of stored liquid. Where smaller pressurised containers and non-pressurised Dewars are stored within buildings, the following points should be considered:

  • store below 50°C in well ventilated place
  • ensure appropriate hazard warning signs are displayed (yellow triangle with exclamation symbol and text: 'Liquid nitrogen')
  • use only properly specified equipment for storing liquid nitrogen
  • do not leave vessels unattended when filling
  • use only proper transfer equipment
  • do not overfill vessels
  • with non -pressurised containers, do not plug the entrance with any device that would interfere with the venting of gas; use only the loose fitting necktube core or an approved accessory
  • do not use brittle plastics which may shatter on contact with the cold liquid
  • do not use hollow dipsticks - use solid metal or wood; if a warm hollow tube is inserted into liquid nitrogen, liquid will spout from the tube due to rapid expansion of liquid inside the tube and gasification
  • any instructions given to staff should detail not only what they are required to do but also what they should not do.
  • See Local rules for procedures that apply for filling vessels from the storage Dewars in room B/E/012

Working with liquid nitrogen in cold rooms

This is permissible providing that risk assessment determines that it is acceptable. The following points should be considered:

  • Ventilation: is it adequate? Most cold rooms do not have any air supply or extract system and so there is little or no air change. Can the door be left open to allow gas to dissipate when vessels are being filled?
  • Do people spend significant periods working in the cold room (on unrelated tasks)?
  • Is the room fitted with an oxygen deficiency monitor / alarm?
  • Is the door fitted with a viewing panel?
  • Is there a ‘panic button’ within the room?

Maintenance of Storage Vessels

All static and transportable pressurised vessels must be maintained and tested in accordance with the Pressure Systems Safety Regulations 2000. Completion of a written scheme of examination and the periodic examination itself is usually carried out by trained engineers appointed by the insurance company responsible for insuring the vessel. The maintenance of transportable vessels is a departmental responsibility and all records of inspections should be filed and readily accessible to present to the enforcing authorities if requested.

Any obvious damage sustained by vessels (either static or transportable) must be reported immediately to the Laboratory Supervisor and if necessary, the vessel should be taken out of use until inspected by a competent person.

Forced ventilation systems and oxygen deficiency alarms should be maintained in good working order.