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Hazards and Proper Handling Procedures for Liquid Nitrogen

Skin/eyes frostbite burns

Direct contact with liquid nitrogen, metal or other material that is in contact with liquid nitrogen or cold nitrogen gas can cause freezing of exposed tissue.

  • Follow all documented procedures for a given task and any additional instructions that may be posted at the work site.
  • Wear the appropriate Personal Protection Equipment (PPE) appropriate for the task.

Required PPE for Handling Liquid Nitrogen
Safety Glasses Cryogenic Gloves Goggles or Face Shield Long Pants without cuffs or Apron Closed-toe shoes Insulated tool handles
Fill dewar with close-loop transfer line X X
Fill dewar with open flow delivery line X X X X
Dewar to dewar transfer X X X X
Removing/storing items in dewars X X X X
Transporting open dewars holding less than 0.5 L X X
Disposing of liquid nitrogen by pouring on ground X X X X
Disposing of liquid nitrogen by bubbling warm nitrogen gas X X
Manipulating protein crystals in dewars X X
Transporting dewars or tanks with lids or closed valves
Disposing of liquid nitrogen by evaporation

Asphyxiation

In confined areas, there is a risk of asphyxiation by displacement of oxygen. Do not use liquid nitrogen in a confined space unless the maximum allowable amount of liquid nitrogen has been posted by the SSRL Safety Officer or if the room is equipped with an oxygen deficiency (OD) alarm.

  • The BL1-5, 9-1, 9-2, 11-1, and 11-3 hutches are equipped with OD alarms. Immediately exit the hutch if the alarm sounds. If the OD alarm sounds when you are outside the hutch, do not enter the hutch. Do not open the door until the alarm has stopped.

  • Cold rooms in general are not equipped with OD alarms. Do not exceed the posted amount of liquid nitrogen allowable in the confined space.  If there is no posting, do not bring liquid nitrogen into the confined space.

Instructions for Liquid Nitrogen disposal

  • Use a warm nitrogen bubbler to evaporate liquid nitrogen when possible.

  • Small amounts of liquid nitrogen (< 0.5 Liters) can be poured carefully in an open area on the floor.

  • Larger amounts must be poured in an open area outside the building.