1. Cryogens are gases and liquids that are stored at extremely low temperatures (less than 150ºC or 238ºF). Common cryogens include liquid nitrogen, liquid oxygen, liquid synthetic air and solid carbon dioxide (dry ice). Hazards may include fire, explosion, embrittlement, pressure buildup, frostbite and asphyxiation.
2. Flammable cryogens such as liquid hydrogen or liquid methane can present extremely high fire and explosion hazards and are prohibited.
3. The presence of liquid oxygen greatly increases the flammability of ordinary combustibles and is prohibited.
4. The most common cryogens typically used on productions are liquid nitrogen, liquid synthetic air and solid carbon dioxide (dry ice) which are typically used to create fog, smoke or other special effects.
5. Cryogens are typically stored and transported in pressurized cylinders similar to compressed gas cylinders. All safety precautions for compressed gas cylinders must also be followed when working with cryogens.
6. A safety data sheet (SDS) must be available for all cryogens. All precautions listed on the SDS and warning labels must be understood and followed. To obtain SDSs, contact the cryogen vendor or call the SDS Hotline at (888) 3627416.
7. The cold boiloff vapor of cryogens rapidly freezes human tissue. In addition, materials such as carbon steel, plastics and rubber become brittle or even fracture under stress when exposed to this vapor.
8. Never make direct contact with cryogens, uninsulated cryogenic pipes or equipment. Exposure can produce skin burns and frostbite. Exposure that may be too brief to affect the skin may damage delicate tissues such as the eyes. Even nonmetallic materials are dangerous to touch at low temperatures.
9. If cryogens vaporize in a sealed container or space they can produce enormous pressure that could result in the rupture of the vessel.
10. Areas of storage and use of cryogens should be properly labeled. Access should be restricted to areas of cryogen storage and use.
11. Cryogens should only be stored in containers that have been designed by the manufacturer for holding cryogens. Such containers are made from materials that can withstand the rapid changes and extreme differences in temperature encountered in working with these materials. Cryogens and their containers are usually obtained from a vendor.
12. Inspect and maintain cryogenic equipment on a regular basis and remove equipment from service when it does not meet manufacturer’s operating specifications.
13. Because of the boiling and splashing hazard, tongs must be used to withdraw objects immersed into a cryogen.
14. Loose fitting insulated gloves made to withstand extremely low temperatures must be worn when handling or transferring cryogens or objects that come into contact with cryogenic vapor.
15. To protect all parts of the skin, long-sleeve shirts and pants should also be worn. Pant legs should cover the tops of footwear so spills cannot get into shoes.
16. Boiling and splashing typically occur when charging of filling a warm container with cryogens or when inserting objects into these liquids. These tasks must be performed slowly to minimize boiling and splashing.
17. Vaporization of cryogens such as liquid nitrogen can cause asphyxiation because of oxygen displacement.
18. Cryogens with potential for oxygen displacement should only be used to create smoke or fog effects at exterior locations or in a large, open and well-ventilated spaces.
19. An oxygen monitoring device should be used whenever a cryogen is used to create a fog or smoke effect in an interior space.
20. Nonflammable cryogens such as liquid nitrogen can condense oxygen from the atmosphere, causing oxygen entrapment in some areas. This unexpected oxygenen-riched atmosphere can produce a potential for rapid combustion. A flammable atmosphere monitoring device should be in operation whenever inert cryogens such as liquid nitrogen are used over large areas.
21. Refillable cylinders should be returned to the cryogen vendor when they are empty or when partially filled and the gas is no longer required.
22. Wear insulated, dry gloves and a face shield when handling dry ice.
23. Add dry ice slowly to any liquid to avoid foaming over.
24. Never allow anyone’s head to be lowered into a container or space containing dry ice or its vapor because of the danger of suffocation.
25. If vapor from dry ice is used to create a large-scale fog or smoke effect in an interior space an oxygen monitoring device should be used.
26. Any cylinder that has a leak in the valve, regulator or fitting should be moved outside to a safe area away from any sources of ignition. Only move a leaking cylinder if it is safe to do so.
27. In the event of a cylinder leak, the cryogen vendor should be contacted. The type of cryogen and the location and condition of the cylinder should be noted. In an emergency, 911 or the local emergency services should be contacted.