Texas Propane’s Propane Vapor Return Valves

propane vapor return valves

Also known as the vapor equalizing connection or vapor equalization valve, the vapor return valve is required on all ASME propane tanks. Texas Propan typically uses this valve during hot summer months in Texas. In the event that liquid must be evacuated from the container, the vapor return valve will be used.

How Texas Propane Operates Vapor Return Valves

Texas Propane primarily utilizes the vapor return valve to relieve the pressure in the tank being filled to prevent over-pressure and potential activation of the safety relief valve during periods of hot weather. The vapor hose from Texas Propane’s delivery truck is connected to the tank’s vapor return valve during the filling process and the excess pressure is vented back to our truck. This allows the vapor pressure to equalize between your tank and our truck, preventing an over-pressure situation at the tank. Simply put, the vapor return valve is a manually operated safety relief valve that prevents propane from being released into the atmosphere.

The Purpose of Texas Propane’s Vapor Equalization

If the pressure of your propane tank gets too high, the safety relief valve will open, which allows propane to release into the atmosphere. When Texas Propane fills tanks on hot days, we will often connect the vapor hose to the vapor return valve. This allows vapor to be safely recovered and contained in our delivery truck. Many individuals believe they are losing gas that they have just paid for. However, this is not the case as only the excess vapor pressure is being relieved from the tank being filled. Consider it this way:

You go to a gas station in the morning and fill your car with gas, place the gas cap back on the tank opening and drive to work. If you were to go out to your car at lunch and open the gas cap, you would hear a hissing sound as you turned the cap. This hissing sound would be gasoline vapors escaping from your gas tank and you did not lose any gas. This is the same principle with regard to but propane but because propane is such a high pressure gas that will vaporize in the atmosphere, the excess pressure is removed during the filling process.

The vapor removed from the tank through the vapor return valve is much less than if it is removed through the safety relief valve.


These are just the basics of propane vapor return valves from Texas Propane. Don’t hesitate to contact us here at Texas Propane with the link below for more information!

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