| 摘要 |
<p>A valve arrangement for automatically stopping the flow through a conduit section on the occurrence of a rupture or leak in the section, the arrangement comprising a closing or blocking valve including a movable closure device mounted at the inlet of the conduit section. The valve is normally open and offers the medium flowing therethrough a resistance resulting in a first pressure drop across the valve in response to the size of the flow. This first pressure drop is arranged to actuate the closure device to thereby close same. A flow sensing device is mounted at the outlet of the conduit section, and an orifice plate or venturi constriction is located between the inlet and outlet sides thereof, so that the medium flowing therethrough generates a second pressure drop in response to the size of the flow, this latter pressure drop being arranged to actuate the closure device in an opening direction. The closure device includes two parts, each movable in relation to the other and actuated by the pressure drops, the first part comprising a blocking body arranged for moving toward a closed position by the first pressure drop to thereby block the flow through the valve when in the closed position, and the second part comprising a servo body arranged for actuation by the second pressure drop to thereby in turn act on the blocking body to counteract its movement toward the closed position.</p> |
