The fuel tank cap is an integral part of the built-in diagnostic and emissions control system. It prevents fuel from leaking out of the filler neck, a significant source of hydrocarbon emissions, and plays an important role in preventing fuel flow. Studies have shown that a defective or missing fuel tank cap can allow up to 114 liters of fuel to evaporate into the atmosphere each year.

Farma fuel tank caps are designed and manufactured to prevent fuel loss mainly through evaporation. The caps are designed to lock in order to prevent fuel theft and vandalism. Opening and closing are easy.