| 摘要 |
A hydraulic safety valve is disclosed which is operative to automatically block a liquid fluid path upon the loss of fluid pressure and to maintain the fluid path in a blocked condition until manually reset. The valve comprises a cylinder, a piston disposed within the cylinder defining multiple spool gates for selectively blocking a valve aperture in the side of the cylinder and for dividing the cylinder into at least a main chamber and a variable volume balancing chamber at one end of the piston. A relatively short fluid path conduit is provided between the balancing chamber and the main chamber. A manually actuable plunger axially aligned with the piston is provided for urging the piston into a valve open position. A biasing means is provided for urging the piston into a valve closed position. In operation the valve is maintained in an open position by downstream back pressure directly through the relatively short pilot fluid conduit coupling the main chamber with the variable volume balancing chamber. The smallest volume of the balancing chamber is at the valve closed position.
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