Main task

The purge valve governs the quantity of air/hydrocarbons that are to be taken into the engine for the current operating conditions.

The fuel that evaporates in the tank is conducted through a pipe to the EVAP canister. The active carbon in the EVAP canister is saturated little by little as it absorbs hydrocarbon fumes. When the engine is started, ambient air is sucked through the EVAP canister via the purge valve and a non-return valve into the intake manifold. Petrol fumes are sucked in as well and are burned up in the engine. When the pressure in the intake manifold exceeds the atmospheric pressure, another non-return valve opens and purging continues on to the turbocharger suction side.