Abstract: A gas purge valve comprising a valve housing that has a valve inlet and major and minor valve outlets, a valve partition mounted in the housing divides the housing into a first chamber communicating with the valve inlet and a second chamber that communicates with the minor valve outlet. A restrictive flow passage is defined in the housing that effects communication between the first and second chambers and has a through flow rate less than that of the minor valve outlet. A minor valve closure device is provided for closing the minor valve outlet to liquid outflow. A differential pressure responsive device mounted in the partition member and displaceable in response to a pressure differential between the chambers and a major valve outlet obturating device responsive to displacement of the differential pressure responsive device into the opening of the major valve outlet when the pressure differential exceeds a predetermined magnitude.