Liquid Nitrogen

Liquid nitrogen is inert, colourless, odourless, noncorrosive, nonflammable, and extremely cold.

Uses​

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• Liquid nitrogen is the commonest material to preserve biological samples at a temperature that stops biological processes.​
• As part of the system to maintain superconducting magnets nuclear magnetic resonance spectroscopy (NMR) and magnetic resonance imaging (MRI).

Recommended Control Measures​

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Procedures​

• Store in well-ventilated areas, if indoors have oxygen alarms to warn of low oxygen levels. ​
• Have procedures in place to minimise the risks from lone working.​
• When decanting liquid nitrogen from a pressurised dewar, always use a transfer dewar, which will reduce spills by controlling the rate of supply to a small transportable dewar.​
• Never travel in lifts or use nitrogen in a small space. A small volume of liquid can evaporate to a 700 fold volume of gas that can displace oxygen to cause asphyxiation and death. Many scientists have died from nitrogen asphyxiation.​
• Properly induct and train new users - use the Local Induction for liquid nitrogen checklist.

Cryostores

• ​For cryostores, keep cryogenically preserved samples at low temperature and only handle as necessary. If handling a number of samples or raising samples to room temperature, do this as slowly as possible and place samples in a secondary container to contain the contents if an explosion occurs. Remember that even heat through gloves when holding samples in your hand will increase the rate of expansion within the vial.​
• Elimination of cryo-storage is sometimes possible with the use of freezers, however there are costs associated with other methods (such as power) and the risk associated if there is a power failure ​

​Personal Protective Equiment (PPE)

• As much skin as possible should be covered (lab coats with elastic cuffs and shoes that cover the top of the foot). Gloves should be worn due to the risk of samples being splashed on the skin, and to prevent cold burns. The type of glove needs to be assessed for the task being carried out.​
• Eye protection needs to worn and the type of protection will depend on the task being done.​

Health Surveillance ​

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None.

Chemical safety library

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> Read more about control measures for chemicals in our chemical safety library