Overfilling the gas (LPG) bulk or cylinder could lead to problems when the propane expands, such as leaks or even explosions, causing property damage and even injury or death.

The risk of overfilling is complicated by the fact that the liquid in the tank or cylinder will expand in warmer weather as pressure in the tank increases. The tank may also cause the relief valve to open and spill gas (LPG) onto the ground.