WATER-HAMMER PREVENTING UNIT FOR CHECK VALVE

IN A WATER-HAMMER PREVENTING UNIT FOR A CHECK VALVE (1) ACCORDING TO THE PRESENT INVENTION, A RETAINER PIPE (15) HAVING OPENINGS (7) AT TWO EDGES THEREOF IS PROVIDED INSIDE A SHORT PIPE (7) TO FORM A CIRCULAR SPACE (16) WITH THE SHORT PIPE (7), AND OPENINGS (17) ARE FORMED ON THIS RETAINER PIPE (15). FURTHER AN ELASTIC TUBE (18) IS PROVIDED ON AN EXTERNAL PERIPHERAL SURFACE OF THE RETAINER PIPE (15) AND COVERS THE OPENINGS (17), AND A COMMUNICATION PATH IS FORMED BETWEEN THE SHORT PIPE (7) AND THE VALVE BODY HOLDER (2), AND THE COMMUNICATION PATH COMMUNICATES THE CIRCULAR SPACE (16) TO THE FLOW PATH (3) IN THE UPSTREAM SIDE OF THE VALVE BODY (5) AND, WHEN A FLUID FLOWS IN THE REVERSE DIRECTION, A PORTION OF THE FLUID IS ACCOMMODATED FROM THE OPENING INTO THE CIRCULAR SPACE (16) BY EXPANDING THE ELASTIC TUBE (18) TOWARD THE CIRCULAR SPACE, AND ALSO FLOWS A PORTION OF THE FLUID IN THE SAID CIRCULAR SPACE TO THE FLOW PATH IN THE UPSTREAM SIDE FROM THE VALVE BODY (5).FIG.1