| 摘要 |
<p>Fluid-activatable shut-off device in an embodiment as a shut-off valve comprises a valve housing (1) formed with a flow passage (2) threrethrough and a movably supported valve body (3) which is movable between an open valve position, in which the valve body (3) is mainly withdrawn from the flow passage (2), which is thereby essentially cleared, and a closed valve position, in which the valve body blocks the flow passage (2). The valve body (3) is arranged to close the valve by abnormal flow conditions by a portion (7) being formed so that the flowing fluid provides a lifting force which affects the valve body (3) and seeks to move it towards the closed position. The valve body (3) may thereby close by an abnormal increase in the fluid flow rate, density or viscosity. The portion (7) may also be supported by an expansion pad arranged to push the lifting surface further into the flow passage as a consequence of changes in the fluid pressure and/or temperature, thereby providing increased lift so that the valve body (3) closes. The valve portion is equipped with plugs (11) for sequentially shutting off the choke channels to the flow of hydraulic/pneumatic fluid between the chambers 4-6 to thereby control the closing speed of the valve body (3), so that surges is avoided in the pipe system in which the valve is installed.</p> |
