Abstract: A dump valve for dumping liquid from the bottom of a tank comprising an elongated valve body insertable into the lower end of the tank so that the valve body extends deeply into the tank, the innermost portion of the valve body having an inner port communicating with the interior of the tank, the valve body having a portion extending exterior of the tank when the body is inserted into the tank, the valve body having a central axial bore extending therethrough and communicating with the inner port for directing liquid away from the tank, a drain passage connected to the exterior portion of the valve body and communicating with the axial bore for draining liquid from the tank, a pair of head plates connected to the exterior portion of the valve body, the head plates being connected to each other and forming a diaphragm chamber therebetween, a diaphragm held in sealed clamping engagement between the head plates and dividing the chamber into two separate compartments sealed from each other, an elongated valve ste

Abstract: A rising liquid level in a gas scrubber for an air compressor is sensed by a float in the scrubber which opens a normally closed pneumatic vent valve whereby a very small pneumatic signal is delivered through a pneumatic spool valve to the chamber of a large diaphragm liquid dump valve on the scrubber which is operated automatically to drain liquid from the scrubber to maintain a safe liquid level in the scrubber. The dump valve mounted on the scrubber side wall penetrates deeply into the scrubber to avoid freezing of the dump valve.