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General Safety Practices



The purpose of this procedure is to insure that adequate policies, procedures, and practices in place for the safe handling of liquid nitrogen in Hematopathology, Ultrastructural Pathology, and Flow Cytometry.

Policy & Personal Protective Equipment

  • Use of the following personal protective equipment is mandatory when decanting or entering an open container of liquid nitrogen:
    • Loose fitting, insulated gloves made to withstand cryogenic liquids. The gloves should be loose enough so they can be thrown off easily and rapidly.
    • Shield all or your skin with long sleeve shirts and trousers. Pant legs should go over the top of footwear so spills cannot get into footwear and cause extreme tissue damage before removal. Rubber aprons, overalls without pockets or cuffs, and hightop shoes are preferred.
    • Always wear chemical splash goggles AND face shield to guard against splashes and possible vessel rupture causing flying debris.
  • The storage and use of all containers of liquid nitrogen must be only in well-ventilated areas. If working in an oxygen-deficient atmosphere, wear an oxygen-supplying respirator. When working in closed area, use an oxygen alarm to alert anyone in the room of oxygen-deficient atmosphere before dangerous levels are reached.
  • Store liquid nitrogen tanks in upright position in cool, dry, well-ventilated area away from emergency exits or heavy traffic areas. Do not store liquid nitrogen tanks in areas of refuge. If cylinders are involved in a fire, safely relocate or keep cool with water spray. Do not store in areas greater than 125°F (51°C).
  • Do not drag, slide or roll storage cylinders. Use suitable hand truck to move vessels and always secure in upright position during movement and transport.
  • The Material Safety Data Sheet for liquid nitrogen is available in each lab using the material.

Special Safety Precautions

  • Extreme temperatures of liquid nitrogen cause most solids to become brittle.
  • Contact to eyes or skin can cause serious frostbite injuries or tissue damage resembling burns.
  • Contact with a cryogenically cooled material is dangerous; do not touch cryogenically cooled material with bare flesh.
  • To minimize chances of freezing material to skin, remove watches and jewelry from the hands and wrists before using liquid nitrogen.
  • When liquid nitrogen warms to a gaseous state it displaces oxygen. Oxygen-deficient atmospheres can cause dizziness, nausea, vomiting, unconsciousness, confusion, and death. Unconsciousness could occur without any preceding signs of danger.
  • Never plug or cover a cryogenic container, otherwise explosions or ruptures may occur.
  • Use only containers designed specifically for cryogenic liquids such as Dewar flasks and cryogenic storage tanks. Fill slowly to protect from excessive stress that can damage the container. Do not fill containers past 80% capacity.
  • Nitrogen is an asphyxiant. Rapid expansion of liquid nitrogen to gas is colorless, odorless, and tasteless and can lead to asphyxiation. Always work in well ventilated areas. Just one liter of gas can expand to 24.6 cubic feet, which is an expansion ratio of 1:696. Liquid nitrogen can rapidly fill small spaces causing very dangerous situations.
  • The Division of Fire Safety and Prevention may be contacted at (301) 496-0487 to evaluate work space requirements for ventilation of oxygen alarms.

First Aid

Signs and symptoms of exposure:

  • Nausea
  • Drowsiness
  • Blue coloration of skin and lips
  • Unconsciousness
  • Death

Remove an incapacitated worker from further exposure and implement appropriate emergency procedures and/or first aid. Immediately contact OMS (301-496-4411) for medical assistance or call code blue (111) if overcome by loss of oxygen.

The following procedures are recommended:

  • EYE CONTACT: Remove victim from source of contamination. Open eyelids, allowing liquid to evaporate. See medical attention.
  • SKIN CONTACT: Exposed tissues should be restored to normal body temperature by running warm water (100-108°F or 37-42°C) over the affected part. DO NOT USE AN OPEN FLAME FOR THIS PURPOSE. Water should never be more than 112°F (44°C) and the affected part should not be rubbed at any time -this can cause further damage to the area. The victim should get emergency care as quickly as possible to minimize further damage and for damage assessment.
  • INHALATION: If a person is overcome by loss of oxygen while working with cryogenic liquids, that person should be moved to a well-ventilated area immediately. A self contained breathing apparatus (SCBA) may be required for rescue so the rescuer does not also fall victim. Artificial respiration should be applied if breathing has stopped. If the person is having difficulty breathing, oxygen should be supplied. Emergency medical help should be summoned.


Last Updated 12/28/2009 10:41:31 AM  

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