| 摘要 |
A differential pressure operated subsurface safety valve (20). A latch mechanism, having ball detents (63), holds the safety valve (20) open until the difference in pressure between fluid in chamber (40) within the safety valve (20) and fluid flowing through the safety valve (20) exceeds a preselected value. The difference in pressure acts upon a piston (37) which is attached to an actuator sleeve (31) causing the actuator sleeve (31) to shift the safety valve (20) from its open to its closed position. The chamber (40) is charged by and equalized with fluid pressure around the exterior of the safety valve (20).
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