Vacuum Bowl Vent Valve & Vacuum/Thermostatic Bowl Vent Valve
The vacuum bowl vent valve and vacuum/thermostatic bowl vent valve are vacuum and vacuum/temperature actuated on/off valves. Vacuum bowl vent valve and vacuum/thermostatic bowl vent valve are similar in appearance. The valves are used in evaporative emission system to control vapor flow from the carburetor bowl to carbon canister. With either valve, the flow path from the bowl to the canister is closed by manifold vacuum when the engine is running. The thermostatic valve also closes the bowl-to-canister flow path when the temperature of the valve is 90°F (32°C) or less (even without manifold vacuum). When the temperature of the valve is 120°F (49°C) or more, the valve is open (unless closed by manifold vacuum).