Compress Gases

A compressed gas is defined as a gas having pressure in the container of 40 psi or greater at 70°C. Also, any flammable liquid having a Reid vapor pressure (RVP) exceeding 40 psi at 38°C is classified as a compressed gas RVP - measure of how quickly fuel evaporates). The regulations define the minimum pressure but not the maximum pressure in a cylinder which can be above 6000 psi for non-condensable gases.

The gas pressure within a cylinder depends on its physical state. For example, "permanent" gases exert a pressure proportional to the amount of gas in the cylinder; while gases which are liquified in the cylinder e.g., carbon dioxide, propane, ammonia, etc., exert vapor pressure as long as liquid remains.

Handling Guidelines

For more information, please see Airgas resources.

  • Gas cylinder connections must be inspected frequently for deterioration and must never be used without a regulator.
  • Never use a leaking, corroded or damaged cylinder.
    • DO NOT attempt to repair a cylinder yourself. Return the cylinder to the manufacturer.  
  • Never refill compressed gas cylinders.
  • When stopping a leak between the cylinder and regulator, always close the valve before tightening the union nut.
  • The regulator must be replaced with a safety cap when the cylinder is not in use.
  • When moving gas cylinders, verify first that the safety cap is in place and only use carts designed for this purpose
  • When transporting cylinders of compressed gases, always secure the cylinder with straps or chains onto a suitable hand truck and protect the valve with a cover cap.
    • Avoid dragging, sliding, or rolling cylinders and use a freight elevator when possible.

Storage Guidelines

For more information, please see Airgas resources.

  • Cylinders of compressed gases are to be strapped or chained to a wall or bench top and are capped when not in use.
  • No more than three cylinders may be chained together with one chain.
  • Cylinders CANNOT be stored in a cart.
  • Do not expose cylinders to excessive dampness, corrosive chemicals or fumes
  • Certain gas cylinders require additional precautions.
  •  Flammable gas cylinders must use only flame-resistant gas lines and hoses which carry flammable or toxic gases from cylinders and must have all connections wired.
  • Compressed oxygen gas cylinders must be stored at least 20 feet away from combustible materials and flammable gases.
  • Flammable gases must be stored separated from oxidizing gases.
    • This is only an exception for gas cylinders used for welding.
Chemical Hygene Plan - Table of Contents