Flush valve

A flush valve comprising:

• a valve housing defining a fluid passageway between a fluid inlet and a fluid outlet, the fluid passageway having a diaphragm valve seat disposed between the fluid inlet and the fluid outlet;
• a diaphragm assembly including a diaphragm and a disc, wherein the disk defines a central axis and an aperture extending axially therethrough, the diaphragm having a primary opening and a bypass opening, the primary opening receiving the disc therein and the bypass opening allowing water under pressure supplied to the fluid inlet to pass from a fluid inlet side of the diaphragm into a chamber in the fluid passageway established by a presence of the diaphragm assembly in the fluid passageway, wherein the diaphragm assembly is disposed in the fluid passageway and is movable axially between an opened position in which the disc of the diaphragm assembly is not in contact with the diaphragm valve seat and a closed position in which the disc of the diaphragm assembly is in contact with the diaphragm valve seat;
• and
• a relief valve configured to selectively control fluid flow from the chamber to the fluid outlet, the relief valve comprising a relief valve housing, a stationary valve element at least partially positioned within the relief valve housing, and a rotatable valve element at least partially positioned within the relief valve housing, wherein each of the stationary valve element and the rotatable valve element have at least one opening and are rotationally positionable relative to one another to regulate fluid flow, wherein the relief valve housing is at least partially positioned within and movable axially along the aperture of the disk while forming a water-tight seal therebetween, and wherein the relief valve housing defines a valve inlet open to and in fluid communication with the chamber and a valve outlet in fluid communication with the fluid outlet;
• wherein in the closed position of the diaphragm assembly and with the relief valve closed, the disc contacts the diaphragm valve seat to form a seal therebetween, and wherein, when the flush valve is activated the relief valve is opened to permit a flow of water from the chamber into the fluid outlet thereby relieving a fluid pressure in the chamber and causing diaphragm assembly to move from the closed position to the opened position such that the disc is unseated from the diaphragm valve seat permitting water to pass from the fluid inlet to the fluid outlet.