| 摘要 |
<p>In a system for leak detection having many valves, it is desirable to have high vacuum valves 66, 68 operated by solenoids at opposite ends of a diffusion pump 60 in order to isolate the diffusion pump 60 during power failure or during an intentional shutdown. A valve 10 having a hard spherical ball 24 fitting a vacuum seal 22 and having a spring means 26 to bias the ball in a closed position will close during a power failure. A bell-shaped actuator 38 connected to a solenoid can be used to open the valve with built-in mechanical advantage. A circuit means can be used to supply high starting voltage to the solenoid and then lower voltage to hold the valve open.</p> |
