Working With Compressed Gas Cylinders
As you can imagine, working with gas cylinders presents plenty of hazards: flammability, reactivity, toxicity, and asphyxiation. Mishandling can lead to explosions or more innocuous dangers...
Compressed gases present both mechanical and physical hazards. If a cylinder valve is accidentally broken, a standard 330 cubic foot cylinder at approximately 2600 psi becomes a rocket attaining speeds of several miles per hour.
The contents of the cylinder may represent additional hazards due to flammability, reactivity, toxicity or asphyxiation. Exposure to corrosive gases such as chlorine, ammonia, and nitrogen dioxide can do irreparable damage to the lungs. Cryogenic gases such as liquid nitrogen can cause tissue damage from extreme cold.
The following list of prudent practices for the safe handling and use of compressed gas cylinders is accordingly presented for your review. Many of the practices have been incorporated into OSHA regulations and are therefore Federal Law.
- Ensure that cylinder contents are properly labeled. Do not depend on manufacturer color codes!
- When transporting a cylinder, insure that the protective cap is in place and securely strap the cylinder to a hand cart. Never drag or slide the cylinder.
- Cylinders must be secured firmly at all times. Firmly belt or chain cylinders individually to a wall, cylinder cart, cylinder rack or rigid structure.
- Keep incompatible gas classes stored separately. Examples would include separating flammables from reactives, which include oxidizers and corrosives (i.e. oxygen, fluorine, chlorine). Oxygen and nitrous oxide cylinders must be separated from flammables or fuel gas cylinders and combustible materials by a minimum of 20 feet, or by a 5 feet high barrier with a fire rating of at least one half hour. Segregate gas storage from all other chemicals.
- Do not expose cylinders to an open flame or to any temperature above 125° Fahrenheit.
- Attach the regulator securely before opening the valve. Open cylinder valves slowly. Do not use a wrench to open or close a hand wheel type valve. If it can not be operated by hand, it should be repaired by the vendor or qualified individuals. Spring loaded pressure relief regulators should be used. When used with hazardous, flammable, or toxic gases, the valve should be vented to the fume hood.
- Under NO circumstances should oil or grease be used on regulator valves or cylinder valves. These substances may be reactive with some gases such as oxygen. Regulators used with oxidizing agents must be carefully cleaned to avoid the possibility of explosion due to contact of the gas with any reducing agent or oil.
- Never leave cylinder valves open when not in use. Segregate empty cylinders from full. When the cylinder is no longer in use, shut off the valves, relieve the pressure in the gas regulators, remove the regulator and cap the cylinder.
- Cylinders should never be emptied to a pressure lower than 170 kpa (25psi) because the residual contents may be contaminated with air if the valve is left open.
- If a cylinder leaks and the leak can not be stopped by tightening a valve gland or packing nut, close the leaking valve, replace the valve cap and move the cylinder to a well ventilated area (i.e. outdoors). Tag the cylinder as dangerous, rope the area off, and notify a supervisor.
It is important that you know and understand the properties, uses, and safety precautions of the gas before use. Cylinder safety devices must be maintained in proper operating conditions to function correctly. Only qualified, gas-supplier personnel should service or correct associated problems with cylinders. For further information contact the Department of Environmental Health and Radiation Safety.