| 摘要 |
<p>A bowl-shaped clapper-type check valve is mounted about a ball and socket joint on an arm. The arm is fixed to a shaft which may be driven manually for opening and closing the check valve. When in closed position the check valve may swing freely in one direction toward an open position and an indicator arm shows the position of the clapper valve at all times. A vane on the downstream side of the clapper valve prevents free rotation about the ball and socket joint when the check valve is open and riding on the fluid stream.</p> |
