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LP Tank Liquid Propane Safety Valve Use

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LP Gas Valve Safety

LP Tank Relief Valve

The safety relief valve is one of the most important and vital valves on any LP Gas container. All propane tanks and cylinders are required by law to be fitted with pressure relief devices designed to relieve excess pressure. The function of a safety relief valve 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 or relief valves.

How Propane Relief Valves Work

Relief valves are held in the closed position by the force of a powerful spring. As long as the pressure inside the tank is less than that of the spring, the valve will remain closed. If tank pressure rises 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.

A relief valve that is sealed shut will not allow the tank to vent excess pressure if it is overfilled or the pressure inside the tank exceeds the working pressure of the container. In a case where the tank is unable to vent to the outside, the tank is subject to rupturing causing more harm and damage than money saved by trying to fix it yourself. Let the propane company or LPG professional handle any problems with the safety relief valve.

You are an adult, please be responsible for your actions. Do not attempt to perform maintenance on gas appliances that should be performed by liscensed professionals

Important Safety Processes to Remember:

A LP Container will respond to heat by releasing some pressure. This means that on a very hot day your gas contaner may release some propane into the atmosphere releasing pressure caused by expansion. You LP tank must be kept in a well ventilated area because of this release function. Gas that is not able to dissipate into the atmosphere will hang around susceptible to a spark. Propane is heavier than air and will settle to the floor or the lowest point in the area. If your gas line valve or liquid propane tank is inside an outdoor kitchen, please review the built in barbeque grill manufacturers materials regarding ventilation of your outdoor kitchen. Generally at least two vents must be built in low to your grill island to allow a cross breeze that will carry gas fumes out of the enclosure.

Over-Fill OPD Valve Information

Before any propane cylinder (4 to 40#) can be filled with propane, the cylinder must have an OPD valve installed on the tank. When filling a propane bottle equipped with an OPD valve, the flow of gas stops immediately when the overfill protection mechanism closes.
Propane bottles equipped with overfill prevention valves are recognizable by the triangular hand wheel at the top of the valve itself. The hand wheel connecting to the valve stem is tamperproof and is not interchangeable with a cylinder not equipped with the overfill prevention safety mechanism. The OPD valve was not designed as a tool to let the bottle filler know when the bottle has reached its capacity. It was designed as a secondary safety mechanism. Bottles equipped with OPD valves are still to be filled by weight as required by law.

OPD Valve Operation

Propane OPD valves operate inside the bottle and are activated as the liquid propane in the cylinder rises to a level that pushes a float upward stopping the flow of gas into the bottle. This action is similar to that of a float valve in a toilet; once the water in the bowl rises to a certain level, the flow of water stops. The OPD valve is actuated during the filling process, not during operation. In other words, inverting a cylinder will cause an OPD float to actuate but it will not stop the flow of gas out of the cylinder. The OPD valve is not designed to restrict flow out of the cylinder, it's only designed to stop flow into the cylinder during the filling process. OPD equipped propane cylinders will allow liquid propane into gas lines and hoses if tipped over or inverted. Overfill Prevention Devices are not a safety mechanism used or actuated during cylinder usage.

OPD valves are also designed to only allow propane into and out of the bottle if attached to the appropriate connection. The threads on this type of connection are visible on the OPD valve at the point of connection. The threads are easily identified by how much larger and farther apart they are as compared to normal pipe threads. OPD valves will not allow propane out of the bottle if it is not hooked up to anything. This is why turning (opening) an OPD handwheel on an unattached bottle does not let propane out, the cylinder needs to be hooked up to allow any gas out.

Check Valve -- Low or No Gas Flow

I get more service requests for low heat output than any other consistent complaint. If you are experiencing low or no heat due to gas flow and you have determined there are no leaks (spray all fittings/joinings with soupy water looking for bubbles caused by leaking gas), you may need to reset the check valve.

Reset The Check Valve:

  • Turn the LP container completely off
  • Disconnect the LP container from the grill
  • Turn the gas BBQ Grill valves to the highest setting
  • Now leave it alone for a few minutes while any residual gas and pressure is released from the gas lines, venturis and barbeque burners.
  • Turn the barbecue grill completely off
  • Reattach the LP container
  • Turn the LP tank valve the the on position by turnng very, very slowly for the first two rotations
  • This will allow the gas to slowly fill the barbeque without blasting through the valve, putting the LP tank in check


If you are experiencing difficulties and would like to schedule an on-site technician contact grill repair or at: 954-2-GRILL-2.



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additional propane safety information available at Propane 101



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