| 摘要 |
Leaks between the valve head and the valve seat of a shutoff valve are detected by providing an air containing housing attached to the valve head and moving therewith into a shut position in respect of a valve seat. The air pressure in the housing increases during the valve shutting movement and a chamber closed by engagement of the valve head and the valve seat when the valve is shut is in communication with the interior of the housing and the exterior of the valve so that pressure changes due to a leak between the valve seat and valve head may be measured.
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