| 摘要 |
<p>A fluid-activatable shut-off device, configured as a shut-off valve, has a valve housing formed with a flow passage therethrough and a movably supported valve body, which is movable between an open valve position and a closed valve position. In the open valve position, the valve body is mainly withdrawn from the flow passage, which is thereby essentially cleared. In the closed valve position, the valve body blocks the flow passage. The valve body is arranged to close the valve by abnormal flow conditions by a portion being formed so that the flowing fluid provides a lifting force which affects the valve body and seeks to move it towards the closed position. The valve body may thereby close by an abnormal increase in the fluid flow rate, density or viscosity. The portion 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 closes. The valve portion is equipped with plugs for sequentially shutting off the choke channels to the flow of hydraulic/pneumatic fluid between the chambers to thereby control the closing speed of the valve body so that surges is avoided in the pipe system in which the valve is installed.</p> |
