Abstract: A valve housing 1 with valve seat 10 incorporated in a fluid line features a closing element 2 with a valve disk 11 and a valve stem 12 extending through and sealed in the housing wall which, on the outer side, is locked by means of a locking pin 17 actuated by a solenoid. Owing to the geometry of the valve disk and the annular gap 20 as well as the action of a spring element 23, the inlet-side pressure acting upon the closing element 2 exceeds the outlet-side pressure, as a result of which the fluid flow via the annular gap is interrupted in only a few milliseconds merely by the permanently present, higher mechanical pressure if the valve stem is released merely by the movement of the locking pin effected by a small and lightweight solenoid 18, actuated on the basis of a signal indicating an event.