Safety First

Liquid Nitrogen (LN2) is commonly used in laboratories everywhere. It is a unique element mostly due to its very COLD temperature of -320 degrees F. Many safety issues should be considered when using Liquid Nitrogen. Here are a few to consider.

• Nitrogen is an asphyxiant and it will, if given the opportunity, deplete the breathable oxygen in an area. Be sure to have adequate ventilation in an area where LN2 is being used. In closed spaces or rooms an Oxygen Depletion Monitor is a good idea.
• Liquid Nitrogen is extremely cold at -320 F. Contact with the skin can cause severe burns and contact with the eyes can render one painfully blind. Use safety equipment when handling LN2. Waterproof Cryogenic Gloves are highly recommended for anyone handling LN2 in any way. In addition Safety Glasses should be worn to protect the eyes. It is also recommended that a headgear and face shield be used to cover the entire face.
• This may sound silly but it is the most common reason for LN2 injuries I have seen in my travels. I will say it, and you will laugh, but it will happen again and again! Do not play with Liquid Nitrogen! Do not pour a bowl of LN2 to see what you can freeze. Things that are dropped from an ambient temperature of 70 degrees F into LN2 at -320 F have to undergo a bone breaking 390 degree F transformation. Things explode commonly within this temperature swing. Golf balls are pretty hard right? They fall to pieces violently in LN2. Don’t play with LN2!
• Liquid Nitrogen is commonly delivered from point A to point B through a Cryogenic Transfer Hose (cryo-hose) as it is the approved method. Check your lab for the rubber hose in use that turns as hard as a baseball bat when delivering LN2. Replace it with a cryo-hose and make your workplace a safer place.
• If you are delivering LN2 through a proper cryo-hose and it is being delivered to a device that has a solenoid valve that calls for LN2 then shuts off when satisfied, check for a safety relief valve to be in place. Without a safety relief valve in place the stainless steel armor cased cryogenic transfer hose can become a four foot pipe bomb given the right circumstances. If the solenoid valve calls for liquid and then shuts off, and someone shuts off the valve on the LN2 source, you have trapped LN2 in the hose. It will not stay trapped for long as LN2 expands to gas at 700 times its own volume instantly. To prevent this potentially catastrophic incident install a cryogenic safety relief in line. Do not mistake a common safety relief for this application as it will freeze in the flow of LN2. It must be a Cryogenic Safety Relief to operate properly.

All of the equipment mentioned is available from Middlesex Gases and Technologies as well as safety programs focused on Cryogenic and High Pressure gases. Contact us today, we look forward to hearing from you.