Abstract: A flow control valve particularly useful for a vapor recovery system of a gasoline station. Gasoline and gasoline vapor flow through separate passages in the valve. A restriction (venturi) is provided in the gasoline passage so that a pressure differential will be produced in the passage as a function of the rate of flow of gasoline passing therethrough. A first diaphragm carrying a valve element which controls the flow of fluid through the vapor passage is responsive to said pressure differential so that the flow rate of vapor passing through the valve will be proportional to the flow rate of gasoline. In each of two alternative embodiments, another diaphragm responsive to gasoline pressure is ganged to the valve to compensate for gasoline pressure variations. In a further embodiment, the vapor control valve operates in an "on-off" mode so that a maximum vapor "draw back" is effected whenever gasoline flow of any magnitude is extant.

Abstract: A flow control valve particularly useful for a vapor recovery system of a gasoline station. Gasoline and gasoline vapor flow through separate passages in the valve. A restriction (venturi) is provided in the gasoline passage so that a pressure differential will be produced in the passage as a function of the rate of flow of gasoline passing therethrough. A first diaphragm carrying a valve element which controls the flow of fluid through the vapor passage is responsive to said pressure differential so that the flow rate of vapor passing through the valve will be proportional to the flow rate of gasoline. In each of two alternative embodiments, another diaphragm responsive to gasoline pressure is ganged to the valve to compensate for gasoline pressure variations. In a further embodiment, the vapor control valve operates in an "on-off" mode so that a maximum vapor "draw back" is effected whenever gasoline flow of any magnitude is extant.