Compressed Gas Cylinders

Compressed gas is a generic term for three different types of products: Compressed gas, Liquefied compressed gas, or Cryogenic liquefied gas.  This page includes an overview of compressed gas cylinder safety issues. For more information, a detailed compressed gas safety guidance document is available.

Hazards

All cylinders present a physical hazard because the contents are under pressure of 2,000+ pounds per square inch. This high amount of potential energy inside the cylinder makes it a potential rocket or bomb. Bumping, tipping, or falling could damage the cylinder. If the valve were knocked off or if the cylinder ruptures in a fire, it can become a missile that can penetrate concrete walls.  This is why it is important to always keep a cylinder in an upright and secured position.
 
The properties of the gas inside the cylinder may present hazards if the gas is corrosive, flammable, toxic, reactive, an oxidizer, or an asphyxiant.  Coupled with the fact that when the gas leaves the cylinder it expands in volume 400+ times, even inert non-hazardous gases can create dangerous situations if they displace enough oxygen in the air in an enclosed space. This is why it is important to use cylinders in controlled ventilated conditions. 
 
Cryogenic gases, or cryogens, pose unique hazards because they are extremely cold. Many materials become brittle at extremely low temperatures. Body contact causes burns similar to thermal burns. Also, cryogens condense oxygen from air, increasing potential for fire.

Storage Rules

  • At all times, keep the cylinder upright and secured with a chain, strap, or bar.
  • If installation of wall chains or bench straps is needed, contact the University Work Control Center.
  • Keep valve caps on cylinders not in use.
  • Label empty cylinders and store them separately from full cylinders.
  • Never store cylinders in a hallway or other means of egress.
  • Flammable -- maintain at least 20 feet from flammable liquids, sources of heat, and cylinders of oxygen or other oxidizers. Bond and ground the cylinder, lines, and equipment.
  • Inert -- store in a well ventilated area because leaks in closed spaces can displace oxygen.
  • Oxygen -- maintain at least 20 feet from flammable liquids. Never use grease or solvents on valves and fittings. Regulators and tubing must be specially cleaned to remove oil.
  • Toxic -- store and use in approved enclosure or fume hood.

Handling Rules

  • Use and store the cylinder in an upright position unless the manufacturer specifies otherwise.
  • Turn all valves off when not in use.
  • Cylinders must be tested every 10 years. There should be a last test date on the top of the cylinder. Notify the supplier if outdated cylinders are identified.
  • Contents should be clearly identified. Do not rely on color coding. Do not remove or deface any marks or tags attached by the vendor.
  • Use a suitable handcart for moving cylinders. Secure the cylinder to it. Do not roll or drag cylinders.
  • Open cylinders with the valve pointing away from you or others.
  • Leave at least 25 psi in spent cylinders to prevent suck-back contamination.

Disposal

Non-returnable empty cylinders and bottles may be disposed of in general waste if the valve stem is removed. For gas cylinders with a Praxair label, contact Praxair at 1-800-283-8348.  If there is no Praxair label contact Steve Stange, of University Surplus Equipment Operation, at 384-4045.  Lecture bottles that are not empty, or have not had the valve stem removed, must be disposed of through EHS by completing the on-line hazardous waste pickup form.

Training

Online information and knowledge training is offered by EHS. Hands-on training for the specific cylinders used in the work area is provided by the employing unit.