| 摘要 |
A velocity check valve is provided which can be installed in oil and gas well production systems to prevent loss of fluid and possible fire in the event of a break or leak in a control line connected to a high pressure flowline or a vessel, such as a separator. In one aspect, the valve includes a seat sleeve containing a ball biased toward unseated position with the ball and sleeve being dimensioned so that when fluid flow past the ball exceeds a maximum rate, the resulting differential pressure across the ball will cause it to move to seated position. The arrangement is such that the ball is free to rotate, except when seated, so that it can present different areas of its surface to the seat to thereby distribute wear on the ball more evenly over its surface. The seat sleeve and ball can be situated in a bore extending from one end of the valve in such a manner that the seat sleeve and ball can be removed from the housing without disconnecting the valve from a line to which it may be connected. Also, a manual push rod arrangement is provided so that the valve can be manually unseated and when the pushing force is removed from the push rod, it will be automatically returned to its retracted position so that the valve cannot be accidentally left in an override or bypass position.
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