| 摘要 |
<p>The invention is a pressure responsive shut-off valve (11) including a valve housing (12) that defines a fluid inlet (13) and a fluid outlet (14) separated by a valve seat (16). A valve closure (17) accommodated by the valve seat (16) moves between open and closed positions to control fluid flow between the inlet (13) and outlet (14). Controlling the valve (11) is a valve operator (25) including a pressure responsive piston (29) that moves between a set position in which the valve closure (17) is separated from the valve seat (16) and a release position in which the closure (17) is seated on the seat (16) to prevent fluid flow between the inlet (13) and outlet. Retaining the piston (29) is a cylinder body (26) that defines an activating volume (27) communicating with the inlet (13) and establishing on one face of the piston (29) a fluid pressure forcing the piston (29) towards its release position, and a reference volume (28) communicating with the inlet (13) and establishing on the opposite face of the piston (29) a reference volume (28). An internal seal (39) isolates the inlet (13) from the reference volume (28) with the piston (29) in its set position while allowing fluid communication therebetween with the piston (29) in its release position. Maintaining the piston (29) in the set position is a latching mechanism (35) that, after activation of the piston (29) to its release position by excessive pressure, can be restored by a manual reset (45, 46).</p> |
