| 摘要 |
The supervisory switch assembly includes an inverted dish-like housing which is mounted directly on the body of a quarter-turn valve, such as a butterfly valve, and encloses the outer end portion of a rotatable valve stem carrying a valve member. One or more switches mounted on inside the housing trigger a warning signal upon being moved from one position to the other. A cam secured on the outer end of the valve stem is arranged to selectively engage each switch actuator, in response to rotational movement of the valve stem, and cause movement of each switch to trigger a warning signal in the event of an unauthorized movement of the valve from the fully open position or the fully closed position. The cam is also arranged to cause the switches to move to a triggering position in the event someone tampering with the switch housing moves the housing relative to the valve body, for example, attempts to lift the switch housing away from the valve housing.
|
