Abstract: A pilot-operated valve suitable for pontoon inflation arrangements contains a main valve poppet urged against a valve seat connecting the inlet and outlet ports of the valve. A portion of the inlet pressure urges a piston carrying the valve poppet away from the valve seat, but this is resisted by a portion of the inlet pressure acting in a pressure volume on the opposite side of the piston. By way of an electrical signal, a manual operation or pneumatic pressure, a pilot valve is opened so as to relieve the pressure on the main valve poppet tending to close it. This allows the valve to open and fluid to pass through the valve assembly. Once the pilot valve has opened pressure from the inlet is applied within the pilot valve to hold it in the open position until the inlet pressure has been substantially reduced. Operation of the pilot valve also allows inlet pressure to be applied to a crossover connection of the valve.

Abstract: A valve is formed with a valve chamber and with an entrance port, a first exit port and a relief exit port each of which communicates with the chamber. A valve member is movably mounted within the chamber, and a pair of valve seats is mounted within the chamber for cooperation with the valve member, one of the seats being movable. The valve member and movable seat are biased in such a manner that the valve is normally seated with respect to both seats. When fluid in the entrance port exceeds a certain crack pressure, the movable seat moves away from the valve member and the fluid flows out the relief exit port. To stop flow out the relief exit port without creating a pressure surge, the valve member, actuated by a control, seats against the movable seat and at the same time moves away from the other seat so that the fluid continues to circulate through the first-named exit port.