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What Is the Scope of This Guideline?
This guideline applies to all lab personnel working with cryogenic materials such as liquid nitrogen and dry ice (carbon dioxide solid).
Cryogenic materials pose significant skin contact hazards and can cause asphyxiation hazards in small or confined spaces. Avoid direct skin contact!
How Do I Protect Myself?
The following PPE is highly recommended when handling cryogenic materials:
- Face Shield
- Safety goggles (not just safety glasses)
- Lab coat
- Long pants (cuffless)
- No shorts
- No open-toe shoes or sandles
Additional Safety Recommendations
Follow any lab-specific handling procedures.
Remove all metal jewelry from wrists and hands (a spill/splash could freeze jewelry to your skin)
Always use tongs when handling objects in cryogenic liquids.
Always wear cryo-gloves when dispensing a cryogenic liquid. Note: Cryo-gloves only provide short-term protection against accidental skin exposures and are not designed to protect skin against prolonged contact.
Only fill a dewar from a transfer line that has a phase separator attached to the end of the line. Phase separators separate gas from liquid preventing an overabundance of gas from surrounding the end of the transfer line and allow only liquid nitrogen to fall into the dewar.
When filling a dewar flask at a filling station, place the phase separator so that it rests on the bottom of the dewar. Do not allow the cryogen to splash into the dewar.
Dispense directly into the dewar. Never use a funnel in the dispensing process. The funnel can freeze creating a splash hazard.
Use stainless steel tubing to transfer cryogens. Never use rubber or plastic tubing. The temperature can cause rubber or plastic tubing to become brittle and crack, spraying the liquid onto surrounding surfaces. Never fill a dewar or storage vessel if the tubing is damaged. (Liquid helium must be transferred through a vacuum insulated tube because of its extremely low heat of vaporization.)
Never overfill a dewar. This may cause liquid nitrogen to leak into the cryotubes stored in the dewar. Upon removal from the dewar, cryotubes may explode when the liquid nitrogen inside is warmed and expands.
Never leave a filling process unattended.
When cooling objects with liquid nitrogen lower them very slowly into the liquid using tongs to prevent boiling and splashing.
Always use an appropriate wheeled cart to transport a dewar or storage vessel. Never pull, push or roll a dewar or storage vessel.
Use extreme caution when handling equipment that has been exposed to a cryogenic material and avoid skin contact. Skin or eye contact with cryogenic liquids, cold equipment and materials that are used in conjunction with cryogens, or splashing liquid may cause severe tissue damage such as burns, frostbite, and eye damage.
DO NOT tamper with pressure relief valves on cryogenic storage containers.
Also ensure that whatever you are putting a cryogenic material into is suitable for the material. Glass dewars should be wrapped in protective mesh or taped.
BEST PRACTICE WHEN TRANSPOTING A DEWAR IS TO AVOID TRAVELING WITH A DEWAR IN A PASSENGER ELEVATOR. Release of a material such as liquid nitrogen in the small space such as an elevator may pose an asphyxiation hazard. Employ the buddy system and have a fellow employee/student remain outside the elevator on the sending and receiving floors. Nitrogen does not have good warning properties and can displace oxygen to dangerously low levels.
Use extreme caution with cryotubes. An explosion hazard exists if liquid nitrogen has entered the tube through any defects or cracks and may expand rapidly causing an explosion/shrapnel hazard.
Handling Emergencies Involving Cryogens
Anticipate emergency situations, have proper handling equipment in the lab and readily available for spills. Check the MSDS to determine what is appropriate.
In the event of a spill or adverse reaction notify lab personnel immediately that an incident has occurred. Do not attempt to handle a large spill/reaction/fire, or one in which you are not trained or equipped for. Turn off all ignition sources if this can be done safely; vacate the area and call for assistance.
Laboratory emergencies should be reported to the public safety office at ext. 6-3333. Public safety will also contact the Department of Environmental Health and Safety at ext. 6-4262. Communicate the following:
- Location of spill/incident
- Type of material involved and quantity
- Injuries involved
- Your location/contact information (or who to contact for further information)
Notify the principal investigator or designated safety officer as soon as possible.
If skin comes in contact with a cryogen or dry ice, run the area of skin under lukewarm water for 15 minutes (do not use hot or cold water). Seek professional medical attention.
If your finger is burned, do not place it in your mouth. This could burn your mouth.
Do not rub the area — this can cause further tissue damage.
In Case of Spill
Do not attempt to clean up a spilled cryogen. If a large volume of gas is released, leave the area immediately and call public safety at exy. 6-3333.
Waste Disposal Requirements
Disposal requests should be called into the Waste Hotline at ext. 6-2561.
Shipping With Dry Ice
Only personnel who have been trained in the proper shipment of dry ice may pack and offer for shipment. If you have not been trained, either contact someone in your group who has or contact the Department of Environmental Health and Safety (EHS) to obtain the Brandeis University Guide to Shipping with Dry Ice. You must read the guide, complete the quiz and return it to EHS prior to packing and shipping anything in dry ice.