propane pressure relief valveThe pressure relief valve is one of the most important and vital safety devices on any LP Gas container. All propane tanks and cylinders are required by federal law to be fitted with pressure relief safety devices designed to relieve excess pressure.  The function of a safety relief device is to keep a propane tank from rupturing in the unlikely event of excessive pressure buildup. Propane tank relief valves are also known as pop off valves, pressure venting valves, safety valves, and relief valves.

How A Propane Relief Valve Works

Safety relief valves are held in the closed position by the force of powerful springs. As long as the pressure inside the tank is less than that of the spring, the valve will remain closed. If tank pressure rises to that of the spring, the valve will open resulting in a hissing sound outside the tank. If the pressure in the tank rises significantly higher than that of the spring, the valve will fully open. When the valve fully opens, it initially makes a loud pop followed by a blast of released propane gas. Once the pressure is released and the tank pressure falls below that of the spring, the valve closes.

Important Pressure Relief Valve Information

Because the safety relief valve performs such a vital role in the protection of the propane tank, it should be maintained and repaired by licensed propane professionals only. Do not ever look into a relief valve or stand over it.

  • Tanks must be empty before relief valves can be replaced.
  • Safety relief valves may need to be replaced if they “pop-off”, meaning that the valve has opened.
  • A protective cover should be placed over the relief valve to ensure proper operation. If the valve has debris in the upper mechanism of the relief valve and it opens, the debris may cause the valve to remain open resulting in a potentially dangerous situation and/or excessive loss of propane. A simple protective relief valve cover can be made from a plastic bag fastened around the external portion of the valve with a rubber band.
  • If a you encounter a relief valve that seems to be “hissing” (opened to relieve pressure) do not tap it or mess with it. If the tank has been recently filled in hot weather and the face gauge reads over 80 or 85%, spray some water from a hose on the tank. This may cool it down and reduce the expansion of the liquid in the tank. Call your propane company immediately and inform them of the situation.

This and other useful propane pressure information can be found at propane101 or by contacting their webmaster at

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