| 摘要 |
Fluid flow control apparatus, comprising a tubular body, a spool within the body, and a timer sleeve movable axially in the body and relative to the spool, to control fluid flow through the spool in response to fluid pressure applied to a closed end of the sleeve; a seat extending within the body to be engaged by the open end of the sleeve, thereby to effect stoppage of flow through the spool, in a flow blocking axial position of the sleeve; and means including a stem extending axially within the spool to define therewith a leakage path for fluid to slowly leak form within the timer sleeve to the downstream exterior of the spool.
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