| 摘要 |
An apparatus usable in a subterranean well includes a valve (10), a first mechanism (28) and a second mechanism. The valve (10) controls communication between an annular region (9) that surrounds the valve (10) and an inner passageway (18) of the valve (10). The first mechanism causes the valve to transition from a first state to a second state in response to pressure in t he annular region. The second mechanism causes the valve (10) to transition between the first state and the second state in response to a pressure differential between the annular region (9) and the inner passageway (18).</ SDOAB>
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