A fire extinguishing system valve comprising a housing, a fluid inlet chamber in the housing, a fluid outlet chamber in the housing, a closing body reciprocable between a blocking state and a release state and which in the blocking state prevents a direct flow of fluid between the fluid inlet chamber and the fluid outlet chamber and in the release state connects the fluid inlet chamber directly in fluid-conducting relationship to the fluid outlet chamber, and at least one manometer (15, 17) which is operatively connected to the fluid inlet chamber or the fluid outlet chamber and which is mounted to the housing, characterised by a venting device integrated into the housing for the at least one manometer (15, 17), wherein the venting device has a plunger (23a, b, c) which is mounted displaceably within the housing and which is moveable back and forth between a pressure transmission position and a venting position, wherein in the pressure transmission position, the at least one manometer (15, 17) and the fluid inlet chamber or fluid outlet chamber are in fluid communication, and in the venting position, fluid communication between the at least one manometer (15, 17) and the fluid inlet chamber or fluid outlet chamber is interrupted, and wherein the plunger (23a, b, c) has an inner through opening which is in fluid communication with the environment, the at least one manometer (15, 17), when in the venting position, is in fluid communication with the inner through opening, and wherein in the pressure transmission position of the plunger (23a, b, c), fluid communication between the manometer (15, 17) and the inner through opening is interrupted. a housing, a fluid inlet chamber in the housing, a fluid outlet chamber in the housing, a closing body reciprocable between a blocking state and a release state and which in the blocking state prevents a direct flow of fluid between the fluid inlet chamber and the fluid outlet chamber and in the release state connects the fluid inlet chamber directly in fluid-conducting relationship to the fluid outlet chamber, and at least one manometer (15, 17) which is operatively connected to the fluid inlet chamber or the fluid outlet chamber and which is mounted to the housing, characterised by a venting device integrated into the housing for the at least one manometer (15, 17), wherein the venting device has a plunger (23a, b, c) which is mounted displaceably within the housing and which is moveable back and forth between a pressure transmission position and a venting position, wherein in the pressure transmission position, the at least one manometer (15, 17) and the fluid inlet chamber or fluid outlet chamber are in fluid communication, and in the venting position, fluid communication between the at least one manometer (15, 17) and the fluid inlet chamber or fluid outlet chamber is interrupted, and wherein the plunger (23a, b, c) has an inner through opening which is in fluid communication with the environment, the at least one manometer (15, 17), when in the venting position, is in fluid communication with the inner through opening, and wherein in the pressure transmission position of the plunger (23a, b, c), fluid communication between the manometer (15, 17) and the inner through opening is interrupted.