Patent ID: 8276617

Claim:
A piston valve for a diaphragm pump, the valve comprising: a central water discharge base including an outer top concave surface having an orientating hole at a lowest point of the top concave surface, an anti-backflow gasket formed of plastic material, the gasket including an integral orientating stem, a convex top surface and a bottom surface, the stem being engageable in the orientating hole of the top concave surface to define a gap between the bottom surface of the gasket and the top concave surface of the discharge base such that a thickness measured from a central top point of the gasket to the bottom surface thereof exceeds a thickness measured from a top edge of the gasket to the bottom surface thereof, and a plurality of water inlet ports disposed around the water discharge base, each water inlet port including an outer top concave surface, an orientating hole at a lowest point of the outer top concave surface, a piston slice formed of plastic material, the piston slice including a convex top surface, a bottom surface and an integral orientating stem engageable within the orientating hole to define a gap between the top surface of the piston slice and the top concave surface of the water inlet port such that a thickness measured from a central top point of the piston slice to the bottom surface thereof exceeds a thickness measured from a top edge of the piston slice to the bottom surface thereof.