Liquid Nitrogen Dispensing

There are many occasions in the lab workplace for employees to take on the task of dispensing liquid nitrogen. There are some simple guidelines that should be followed when handling this hazardous product.

Liquid Nitrogen (LN2) is an inherently dangerous product to handle for a number of reasons but the most obvious one is its temperature. At -321 F this product will cause rapid frostbite upon contact with the skin. Splashing LN2 can cause serious and permanent eye injury.

Precautions should be taken when handling this product to prevent such injuries. Here are some common guidelines:

• Before dispensing LN2 always check the pressure gauge on the LN2 vessel to ensure the pressure is at or close to 22 psi. At higher pressures LN2 can be uncontrollable and excess splashing can result.
• All personal safety equipment must be kept in close proximity of the LN2 dispensing site.
• Always use waterproof cryogenic gloves, elbow length or longer is preferred. Order your gloves extra large so they will fit others in the lab that may be handling the LN2.
• Use double eye protection, safety glasses with side shields and over that is a face shield supported by a head gear. The headgear should have a ratchet type sizing adjustment so it can be used by others in the lab that may be handling the LN2.
• Keep extra face shields in stock for the headgear should one get dirty the end user has a replacement at hand.
• Use an approved cryogenic transfer hose. A thick rubber hose is not a suggested method of transferring LN2 but is in common use.
• A phase separator should be employed on the end of the cryogenic transfer hose to ensure a smooth flow of LN2.
• A Cryo-Hanger should be used in the transfer process as it gives the operator somewhere to hang the frozen cryogenic hose when the transfer is completed.
• Ensure that the vessel receiving the LN2 is clean and free of any accidentally introduced items. Many items explode when they come in contact with LN2.
• Use acute common sense when handling LN2. Pay attention to the task at hand and avoid distractions. LN2 contact is unforgiving.
• Do not, under any circumstances “play” with liquid nitrogen. This is where most accidents with this product occur. This product will freeze almost anything but as stated before, many items explode either in the LN2 or when they are removed due to the nearly 400 degree temperature swing the item is subjected to from LN2 temperature to room temperature.

We have a thin lens over our eyes and that lens is all that hold back the fluid in the eye socket. A drop of LN2 in the eye can crystallize that lens and it will shatter like fine, thin glass allowing the fluid to flow freely. Wear your personal safety equipment on every occasion and maintain your common sense during the task.

All of the equipment mentioned above is available from Middlesex Gases & Technologies by calling us at 617-387-5050.

Mike Lee

Specialty Gas Manager

Middlesex Gases & Technologies