LEAK PREVENTING STRUCTURE FOR BACK PRESSURE CHAMBER OF DIAPHRAGM VALVE

摘要

PROBLEM TO BE SOLVED: To prevent a leak from a back pressure chamber of a diaphragm type pressure control valve. SOLUTION: A valve element 30 is provided to communicate the back pressure chamber 11 formed inside of a casing 5 of a pulsation damper 1 having a diaphragm 10 with the atmospheric air through an atmospheric air port 15 of the casing and to close the atmospheric air port when the pressure of the pressure chamber 13 in the casing is lowered. A cap cover 17 is fitted on the outer surface of the casing 5 to cover the atmospheric air port 15. The outside air is led into the atmospheric air port through a clearance 23 between the cap cover and the casing outer surface, and a filter 20 is interposed between the cap cover and the casing end surface to filter the air flowing from the clearance.