Patent ID: 8069877

Claim:
A method of controlling a water flow rate in a flush valve, comprising: receiving flush water at an intake water pressure during a flush cycle; providing flush water to a flush valve at a constant flow rate; moving a piston valve between a valve open position and a valve closed position to affect the flow rate of flush water through the flush valve by altering the size of openings through which the flush water travels based on the intake water pressure; wherein the piston valve includes an inlet regulator piston disposed in an inlent housing, the inlet regulator piston having regulator openings in a periphery thereof and the inlet regulator piston being movable based on the intake water pressure, the movement of the inlet regulator piston in the inlet housing affecting the alignment of the regulator openings with housing openings in the inlet housing, wherein the flow rate of the flush water through the inlet flow regulator is determined by the alignment of the regulator housing openings, and discharging flush water from the flush valve for a predetermined time interval, wherein a substantially constant flow rate of the flush water through a discharge outlet is maintained through the flush cycle.