PetroClear TV-2 Fill Cap & Adaptor

The vented fill cap is designed to maintain a constant tank pressure; reducing evaporation loss, contamination intake, over-expansion and contraction of the tank. Plus, the vented fill cap can reduce spillage during transport. Fuel temperature in the tank rises during the day, causing the contents to expand and the fuel vapors to escape. This process creates pressure. The tank and its contents cool down at night, creating a vacuum that draws moist air into the tank. By maintaining a semi-closed system, the amount of fuel vapors that escape into the atmosphere and the amount of moisture taken into the tank are reduced.