Abstract: A check valve includes a spherical closing member arranged in a flow duct of a valve body. The flow duct includes guide ribs with stop surfaces. The spherical closing member is displaceable by medium flowing through the valves between the stop surfaces and a sealing portion. An annular portion is arranged between the sealing portion and the guide ribs. The annular portion has an internal bore which is slightly greater than the diameter of the spherical closing member. Starting from the equator of the spherical closing member resting against the sealing member, the partial length of the internal bore of the annular portion in flow direction of the medium is 1/7 to 1/2 of the diameter of the spherical closing member.

Abstract: In a flap valve, a casing is provided forming a flow opening through the valve. A flap is pivotally mounted in the casing for closing the flow opening. The casing is formed of two annular parts secured together by bolts. The two casing parts have a plane of contact with a seal secured between the two parts and extending around the opening in the plane of contact. The seal includes a pair of spaced rings with arcuately shaped seal members extending between and interconnecting the rings. Each seal member has an circumferentially extending closed hollow space forming an air cushion. When the flap is placed in the closed position in the flow opening, a slight torsional moment is executed against the seal which is formed of a wear-resistant material so that a good sealing effect is obtained.

Abstract: A butterfly valve includes a gasket on the pivotable member which has a peripheral ring portion and two end rings which are concentric to the shaft supporting the pivotable member, each end ring having a flange held under spring pressure between the pivotable member and bushings on the shaft ends. The gasket thus seals the valve against leakage to the outside and to the shaft.