| 摘要 |
<p>A ball seat (3), formed of a synthetic resin, is mounted at each end of a flow passage (21) in a ball (2) of the valve. A sealing end portion (32) of the ball seat contacts the spherical surface of the ball only in the closed position of the ball. In the open position, a lip (32) falls within a recess (22) surrounding the end of the flow passage in the ball. A gap of 0.3 to 0.7 mm is formed, in the open position, between the wall surface of the recess and the end of the lip. The end of the lip should fall, in the open position of the ball, about 0.2 mm inside an imaginary continuation of the surface of the ball at the recess.</p> |
