| 摘要 |
A well safety valve for controlling the fluid flow through a well tubing in which the valve closure member is controlled by a longitudinal movable tubular member which opens and closes the valve, can lock the valve in an open position, can telescopically collapse to avoid damage to the valve, and can be reset either manually or automatically. The tubular member includes first and second telescoping sections which are releasably locked together in an intermediate extended position for normally opening and closing the valve on movement of the tubular member. The releasable locking means is constructed to release upon the application of a predetermined force less than a force sufficient to cause damage to the valve whereby on application of an excessive force the sections will telescope towards each other preventing damage to the valve. Coacting shoulder means are provided between the valve body and lower telescoping member to automatically extend the telescoping sections on upward movement of the tubular member.
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