A flush valve has a relief valve that has a stationary valve element and a rotatable valve element each having at least one opening, and being rotationally positionable relative to one another to regulate fluid flow. A disc contacts a diaphragm valve seat to form a seal between the disc and the diaphragm valve seat when the diaphragm assembly is in the closed position and with the relief valve closed. When the flush valve is activated, the relief valve is opened to permit a flow of water from the chamber into the fluid outlet. The opening of the relief valve relieves fluid pressure in the chamber and causes diaphragm assembly to move from the closed position to the opened position. The disc is unseated from the valve seat which permits water to pass from the fluid inlet to the fluid outlet when the diaphragm assembly is in the open position.
