| 摘要 |
PCT No. PCT/GB96/01798 Sec. 371 Date Jan. 26, 1998 Sec. 102(e) Date Jan. 26, 1998 PCT Filed Jul. 26, 1996 PCT Pub. No. WO97/05362 PCT Pub. Date Feb. 13, 1997A downhole check valve includes a body (32) defining a flow passage and a valve assembly (34, 42, 44) mounted in the body, the valve assembly including a valve member (34) movable from a first configuration to a second configuration. In the first configuration the valve member prevents flow in one direction through the passage, and in the second configuration the valve member is retained in an open position. A valve member retaining sleeve (48) is normally restrained in a first configuration and biassed for movement to a second configuration. The retainer is held in the first configuration while the valve member (34) is in the first configuration and is releasable from the first configuration to move the valve member to the open position and retain the valve member in the open position. |
