| 摘要 |
PROBLEM TO BE SOLVED: To provide a trunnion type ball valve capable of improving a sealing characteristic between a ball seat and a valve member, preventing leakage, preventing wear at the ball seat, and also improving durability even under application of high pressure.SOLUTION: A seat retainer 14 having a ball seat 15 installed therein is arranged in at least an upstream side of a ball 12 having a through-pass hole 12a installed in a body 11 and the ball 12 is rotatably arranged through a stem 13. The ball seat 15 is installed in an installing groove 26 formed at the seat retainer 14 under its free state. An inner diameter size L1 at a part A that is a fulcrum position of a rear surface seal of the ball seat 15 is arranged near the inner diameter rather than a seal location 25 of the seal seat 15, the ball seat 15, under application of high pressure, is resiliently deformed to open while the part A being applied as a fulcrum point to cause the seal location 25 to be sealed in at least a surface contacted state from the outer diameter side toward the inner diameter side.SELECTED DRAWING: Figure 2 |
