Gas Cylinders

Hazards of Compressed Gases

  1. Mechanical failure of the cylinder, cylinder valve, or regulator can result in rapid diffusion of the pressurized contents into the atmosphere, leading to explosion, fire runaway reaction, or burst reaction vessels.
  2. Unsecured cylinders can be knocked over very easily, causing serious injury and damage. Impact can shear the valve from an uncapped cylinder, especially if a regulator is attached, causing a rocking action or penwhelling leading to personal injury.
  3. Gas cylinders may contain flammable, toxic, or corrosive gases; asphyxiants; or oxidizers.

Storage and Handling of Compressed Gases

  1. Check to make sure that a label is attached or the identification of the contents is stenciled on the cylinder when a cylinder is brought to you. Do not accept a cylinder if the contents are not clearly identified. Do not rely on color coding to identify the contents of a gas cylinder; color coding is not standardized.
  2. To transport a cylinder, use a hand truck equipped with a chain or belt for securing the cylinder. Make sure the protective cap covers the cylinder valve. Never move a cylinder while a regulator is attached. Do not move cylinders by carrying, rolling, sliding, or dragging them across the floor. Do not transport oxygen and combustible gases at the same time.
  3. Secure gas cylinders to prevent them from falling over. Chains or a clamp-plus-strap assembly are the most common methods of keeping cylinders upright. Make sure the chain is high enough on the cylinder to keep it from tipping over. Cylinder supports are available from the stockroom.
  4. Do not store incompatible gases together. Store cylinders of oxygen at least 20 feet away from cylinders of hydrogen or other flammable gases.
  5. Store cylinders away from heat (never in areas above 125C), including steam or hot water pipes, and away from areas where they might be subjected to mechanical damage.
  6. Store full and empty tanks in volatile solvent room. Place "Empty" ring around the top of the tanks when removing them from service to avoid accidental connection to an empty to a pressurized system, causing backflow into the tank.
  7. Ground cylinders of combustible gases (e.g., to a water pipe) to prevent buildup of static electricity. Keep cylinders away from locations where they might form part of a electrical circuit.
  8. Keep the protective cap that comes with a cylinder of gas on the cylinder when it is not in use. The cap prevents the main cylinder valve from being damaged or broken.
  9. NFPA codes specify maximum quantities and sizes of hazardous gas cylinders in laboratory areas. A typical laboratory in the department may have no more than three standard cylinders of flammable gases and/or oxygen; two of liquefied flammable gases; and three 4' X 15" cylinders (or volume equivalent) of gases with high Health Hazard Ratings (see NFPA 45).
  10. Corrosive or unstable gases should be ordered in the minimum quantities necessary and stored in a hood or other safe, dry area. Corrosive gases, if stored for long periods, will corrode the valve internally and may be impossible to open or if opened, may not close.
  11. Gases with Health Hazard Ratings of 3 or 4, or a rating of 2 with no physiological warning properties, MUST be kept in an hood or other ventilated enclosure. No more than three cylinders with ratings of 3 or 4 may be kept in one enclosure.
  12. Cylinders not needed for current use should not be stored in laboratories. Recommended maximum retention periods for gases are 36 months for liquefied flammable gases, flammable gases, and oxygen; 6 months for corrosive or unstable gases or those with a Health Hazard Rating of 3 or 4.
  13. When a cylinder is empty (preferably not less than 25 psi residual pressure), close the valve to prevent air and moisture from entering the tank, remove the regulator (purging it if necessary to safely remove toxic or corrosive gases), replace the cylinder cap, and label the tank "EMPTY." Use a hand truck to return the cylinder to the gas cylinder storage in the Volatile solvent room.
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