| 摘要 |
<p>1535357 Wells &c SCHLUMBERGER TECHNOLOGY CORP 18 Feb 1976 [26 Feb 1975] 6285/76 Heading E1F [Also in Division F2] Safety valve apparatus adapted to be installed at a subsurface location in a flow conduit, e.g. in a gas storage well, includes a valve 21 which is closed in response to a decrease in the flowing pressure in the conduit adjacent the valve 21 to a value that is below a dome reference pressure, and a flow restriction 30 upstream of the valve 21 for causing the flowing pressure adjacent the valve 21 to drop below the dome reference pressure in response to abnormal conditions in the conduit downstream of the valve means e.g. a gas escape at the surface. As described the valve 21 and restriction 30 are mounted in a housing 11 which is hung from an anchor and packer assembly (not shown) so that the entire gas flow passes through the restriction 30, upwardly through passages 28, 31 and through the valve ports 33. The flowing pressure of the gas adjacent the valve 21 acts, via ports 65 and a double bellows 56, 78 filled with incompressible fluid, against the reference pressure of an inert gas in a chamber or dome 84. Should the gas escape at the surface, the restriction 30 causes the pressure adjacent the valve 21 to drop below the pressure of the gas in the dome 84 thus causing the bellows 56 to expand. Expansion of bellows 56 raises a sleeve 54 which in turn raises a release sleeve 48 until a reduced diameter portion 89 of sleeve 48 reaches the level of ball detents 45. Inward movement of the ball detents 45 releases valve member 40 and allows spring 57 to shift the valve member 40 to close the valve ports 33, thus cutting off the passage of gas through the apparatus. The valve 21 can be opened by increasing the pressure of the gas downstream of the valve 21.</p> |
