| 摘要 |
A stop valve for a vacuum apparatus comprises a valve casing having an inlet port and an outlet port, a main valve element housed in the valve casing for selectively opening and closing a flow passageway for causing the inlet port to comunicate with the outlet port, an auxiliary valve element for selectively opening and closing an orifice formed in the main valve element and capable of opening the flow passageway by opening the orifice when the main valve element is closed, a valve shaft for driving the main valve element and the auxiliary element, and a control mechanism for controlling the operation of the valve shaft and opening the main valve element after the auxiliary valve element has been opened.
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