Is Your Barbecue Propane Cylinder Being Properly Filled?

hand turning the valve on a propane tank

A propane barbecue set relies upon a propane tank to deliver fuel into the burner, as opposed to a charcoal barbecue that uses charcoal briquettes as fuel. The gas tank is probably the most difficult part of the propane barbecue to manage and use successfully.

Propane is a highly flammable gas and must be treated with respect when being handled and filled. Filling the propane tank is a job for a professional, but there are tricks and tips which should be learned in order to establish whether the propane barbecue tank is being correctly refilled, and also to ensure that the tank is not overfilled, which can be a serious problem.

Refilling a Propane Cylinder

two rusting propane tanks sitting side by side

Refilling a new tank from a propane barbecue can be problematic. There is a recognized ‘first time filling’ technique which has to be used in order for the tank to be properly filled.

In order to fill the tank fully, air inside the tank, which can sometimes be as much as 100 psi, must be expelled. This must be done by purging the tank, using propane vapor, not liquid. The gas station should have a cylinder which connects to your propane tank via a hose. The professional should use vapor drawn from the station’s cylinder to purge the tank.

During purging, the tank should not be filled with gas, only vapor. Some stations might solve this problem by using a vacuum purge method, which uses a pump or gas compressor to force air out of the cylinder.

After this purging has been done, the container is ready to be fully filled. Ambient temperatures do not affect gas tank filling.


a grill filled with foods

Overfilling the tank is a serious risk. An overfilled propane tank can explode, causing damage and even injury. The risk of overfilling is complicated by the fact that the liquid in the tank will expand in warmer weather as pressure in the tank increases. If the tank is too full, this has no place to go. As well as exploding, the tank may also cause the relief valve to open and spill propane. This is not only a waste of money, but also a safety hazard.

Due to the dangers of overfilling a propane barbecue gas tank, there are a number of devices designed specifically to prevent this. For example the Overfill Protection Device — a float in the tank that automatically prevents filling once the gas is at 80 percent capacity, leaving enough room for the liquid to expand.

Taking care to ensure that the propane barbecue tank is full, but not over-filled, ensures a long life for the cylinder, and also preserves the safety of the cook and his friends.