FLUID ON-OFF VALVE DEVICE

摘要

A check valve (fluid on-off valve device) 1A, capable of attaining high sealability in either case where a differential pressure is high or low, comprises a valve body assembly (valve body) 3A contacting and separating from a valve seat portion for communicating and blocking a fluid passage. The valve body assembly 3A comprises a valve body 10, a low-pressure seal portion 12 constituted out of soft material and a high-pressure seal portion 13 constituted out of harder material than the low-pressure seal portion 12. In blocking a fluid passage, when a differential pressure between an upstream path 7 and a downstream path 8 in the fluid passage is relatively low, the low-pressure seal portion 12 comes into close contact with a protrusion 6 to block the fluid passage, while when the differential pressure is relatively high, the low-pressure seal portion 12 is compressively deformed by the differential pressure and the high-pressure seal portion 13 comes into close contact with the valve seat body 4, thus blocking the fluid passage.