Patent ID: 8408482

Claim:
A sprinkler for distributing water, the sprinkler comprising: a housing defining an interior surface; and a pressure regulating apparatus mounted in the housing, the pressure regulating apparatus including: a body wall having an exterior surface and defining an inlet for receiving water into the apparatus, an outlet for delivering water from the apparatus, a passageway between the inlet and outlet, and a first cavity surrounded by the wall; a pressure responsive member having at least a first radially outer surface portion defining a portion of the passageway where water pressure of water in the passageway exerts a force on the first radially outer surface portion, and at least a second surface portion of the pressure responsive member received in the first cavity at a generally constant reference pressure, the pressure responsive member shiftable in response to pressure of the water, and the first cavity generally sealed from the passageway to prevent the flow of water and air therebetween; and a valve seat in communication with the passageway, wherein the pressure responsive member moves towards the valve seat when pressure against the pressure responsive member exceeds a predetermined level to reduce the flow of water through the passageway; and the exterior surface of the body wall positioned a distance from the sprinkler housing interior surface and generally sealed therewith to define a second cavity in communication with the first cavity and in communication with an exterior environment of a portion of the sprinkler; wherein the housing includes: a stationary housing including an inlet for receiving water under pressure from a water source, a moveable housing received within the stationary housing and having a retracted position relative to the stationary housing when the sprinkler is shut off and having an extended position relative to the stationary housing with the sprinkler is activated to distribute water from a nozzle on the moveable housing, wherein the first cavity is defined by the pressure responsive member and a first cavity surface stationary relative to the moveable housing, and a first seal member positioned to form an interface between a portion of the pressure responsive member and the first cavity surface to generally prevent the flow of water and air across the interface.