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Compressed gases include:

  1. Any gas or mixture of gases in a container having:
    a. Absolute pressure exceeding 40 psi (276 kPa) at 70° F, or
    b. Absolute pressure exceeding 140 psi (717 kPa) at 130° F; or
  2. A sealed container of a liquid having a vapor pressure exceeding 40 psi (276 kPa) at 100° F.

12.4.1 Hazards of Compressed Gases

Compressed gases can pose both physical and health hazards. The pressure in a gas cylinder makes it a potential rocket that can punch through walls. The gases frequently represent inherent hazards independent of pressure such as flammability, corrosivity, toxicity, and excessive reactivity. Gas released from a cylinder may also have the potential to asphyxiate nearby workers by displacing air in a space.

12.4.2 Handling Procedures for Compressed Gases

Compressed gas cylinders must be handled with caution at all times. It is particularly important to protect cylinder valves from breakage. The following are two sets of handling instructions, one for gas cylinders in general and the other for poisonous and flammable gases.

  1. Use gas cylinders in a well-ventilated area.
  2. The contents of a cylinder must be clearly identified on the cylinder with a non-removable label.
  3. Do not accept a gas cylinder that is damaged or shows signs of corrosion from the manufacturer.
  4. Clearly label all gas lines leading from gas cylinders.
  5. Compressed gas cylinders must be firmly secured to the wall at all times. Contact Facilities Engineering if you need wall chains installed or modified.
  6. Access to the cylinder valve must be unobstructed at all times.
  7. Pressure regulators must be equipped with pressure release valves.
  8. Do not use oil on regulator valves and cylinder valves.
  9. Do not empty gas cylinders to pressure lower than 25 psi (172 kPa). Contamination of residual contents could occur if the valve is left open.

12.4.3 Transport of Compressed Gases

  1. Never roll or drag cylinders. Strap cylinders onto a hand truck if they must be transported even a short distance. The valve cover and caps must be in place whenever cylinders are moved.
  2. Use service or freight elevators.
  3. Transport asphyxiants and poisonous gases using one of the following methods:
    a. Exclude people from the elevator by posting a sign on the cart carrying the cylinder. The sign should read Do Not Enter. Compressed Gas Transport.
    b. Buddy system: Transport the cylinder using two employees. One employee travels with the cylinder in the elevator while the second employee uses the stairs to meet the cylinder and transporter at the destination floor.

12.4.4 Flammable and Poisonous Gases

Flammable and poisonous gases are subject to fire code regulations. Notify EH&S before ordering flammable or poisonous gas cylinders to determine the proper safety and control measures as well as permit requirements.

Flammable gases include:
  • Acetylene
  • Carbon monoxide (toxic)
  • Ethane
  • Ethylene
  • Hydrogen
  • Isobutane
  • Methane
Poisonous gases include:
  • Arsine (flammable)
  • Chlorine
  • Cyanogen (flammable)
  • Fluorine
  • Hydrogen fluoride
  • Hydrogen selenide
  • Hydrogen sulfide (flammable)
  • Hydrogen cyanide (flammable)
  • Nitric oxide

12.4.5 Additional Requirements for Flammable and Poisonous Gas Cylinders

  1. Store and use flammable gas cylinders in an area segregated from other gases.
  2. Flammable gas cylinders must have fusion plugs.
  3. Poisonous gases must have valves capped or plugged with approved closure devices.
  4. No more than three cylinders can be kept or used inside a gas cabinet or chemical fume hood.
  5. Respirators may be necessary when working with poisonous gas. Contact EH&S before using a poisonous gas.

12.4.6 Storage of Compressed Gases

All gas cylinders must be stored upright and firmly secured to a wall at two points. Poisonous and flammable gases must be segregated from other gases and stored in an adequately ventilated area.

Leaking flammable or poisonous gas cylinders must be vented at a rate not to exceed 10% of the explosion limits or IDHL (Immediately Dangerous to Health and Life).

Store poisonous gas cylinders in a gas cabinet or chemical fume hood.

12.4.7 Disposal of Compressed Gas Cylinders

All empty cylinders must be clearly marked Empty and must be collected by the vendor.

12.4.8 Emergency Procedures: Compressed Gas Leak

  1. Leave the area immediately and get to fresh air. Call EH&S to report release and exposure.
  2. Complete an Accident-Illness Report Form as soon as possible and mail to EH&S at J3-200.
  3. Call EH&S to evaluate hazard. Notify vendor of the faulty equipment and arrange for immediate replacement.