Abstract: A drain valve assembly is mounted in the bottom of a fuel tank (10) to allow draining of condensate. The tank (10) is drained of fluid by the use of a tool (27) pushed upward against the piston (18) of the valve assembly separating it from its seat (15) in the valve housing (12) allowing liquid which has entered the housing (12) from the tank (10) through openings (16 ) to exit around the periphery of the unseated valve. If the valve assembly base is struck by lightning, a blast pressure occurs that can drive the poppet of a standard valve open allowing the electrical energy to enter the tank (10) causing a potential explosion. With the present valve assembly the pressure is allowed to pass through passage (20) in the piston (18) to apply a closing force on the surfaces (21, 22) and the inner end of the piston (18) which is greater than the opening force due to the area difference and the valve assembly remains closed.

Abstract: A system for controlling liquid flow from an inlet into a tank comprising a normally closed poppet valve controlled by dual pressure chambers each containing a diaphragm movable by the pressure of the liquid in the inlet to cause the valve to close. Pressure against the diaphragms is relieved by bleed passages extending from the chambers which are closed by dual solenoid operated closing mechanisms. Actuation of either one or both of the mechanisms can open the bleed passages.