Patent ID: 9605419
Date: 2017-03-28
CPC Classifications: E03D,F16K,Y10T

Claim:
1. A flush valve system comprising: a hollow valve body having an inlet, an outlet, and a main valve seat there between; a piston assembly movable within the hollow valve body and configured to seat upon the main valve seat to seal the inlet from the outlet; an upper pressure chamber positioned above the piston assembly within the hollow valve body, the upper pressure chamber in fluid communication with an interior of the piston assembly; a relief valve positioned within the piston assembly, the relief valve sealing the upper pressure chamber and interior of the piston assembly from the outlet; the main valve seat having an upper ring, a middle portion, and a lower skirt and having a main valve seat surface for engaging the piston, an outer sidewall, and an inner sidewall defining a flow passage with a piston-side opening and an outlet-side opening, the flow passage having a reduced diameter portion at a transition from the upper ring to the middle portion below the main valve seat and the inner sidewall tapering from the reduced diameter portion to the outlet-side opening; the piston-side opening including a counter bore on the main valve seat surface, the counter bore circumscribing a portion of the flow passage and a curved shoulder transitioning from the counterbore to the inner sidewall and the inner sidewall tapering from the reduced diameter portion to the outlet-side opening.