Abstract: A shut-off organ for a fluid line, particularly for the turbine feed line of a hydroelectric power plant, has a housing and a clack valve in the housing that can be pivoted between an open position and a shut position. The clack valve has at least one swallowtail-shaped groove, into which an elastic sealing element having an essentially wedge-shaped cross-section that narrows towards the outside is laid. The sealing element rests against a conical sealing seat of the housing with its narrowed outer edge, forming a seal, in the shut position, thereby shutting off the shut-off organ. The possibility of the sealing element being sucked out is precluded even if the clack valve is opened while it stands under high hydraulic pressure, due to a rigid pin that extends through the sealing element essentially crosswise to the longitudinal expanse of the groove.

Abstract: A butterfly valve has a disc which is pivotally mounted inside the passage through the housing and movable between open and closed positions. In its closed position, a seal is established between the valve housing and the disc with a seal ring that has a flat portion clamped to the housing with an axially movable pressure ring and an inwardly extending, resilient seal ring portion that engages a conical periphery of the disc. A plurality of threaded, circumferentially spaced-apart locking bolts in a segmented retainer ring attached to the valve housing are tightened against the pressure ring to secure the seal ring to the housing. The locking bolts are disposed in through holes in the support ring. Each through hole includes a threaded portion, which is contiguous with the side of the support ring facing the pressure ring, and an unthreaded section which terminates at the outer side of the pressure ring.