a pressure control valve for use in conjunction with a riser for supplying water , in case of a fire , at all levels of a multiple story structure at a predetermined regulated static and flowing discharge pressure . the valve includes a hand wheel on a stem engaging the valve , a normally inaccessible static pressure control collar on said stem and a diaphragm sensitive to flowing discharge pressure at the discharge side of the valve tending to close the valve and a spring opposing the diaphragm , said hand wheel arranged to move said valve stem relative to said diaphragm and close the valve without altering the pressure adjustment thereof .