VALVE STRUCTURE FOR SHUT-OFF VALVE

摘要

PROBLEM TO BE SOLVED: To provide a valve structure for a shut-off valve having a small size and vacuum retaining capability. SOLUTION: The valve structure for the shut-off valve comprises an annular groove 33 circulated on one side face of a valve disc opposed to a valve seat and a seal member 34 fitted to the annular groove 33. The seal member 34 has a base and a swollen portion 206 molded integrally with the base. The swollen portion 206 has a fist recess 202 and a second recess 204 on the side of the base so that the swollen portion 206 is deflected to the side of second recess 204 and pressed against the valve seat during sealing of the seal member 34 to secure a wide shut-off plane.