Abstract: A double seat valve includes a valve housing and two valve closure members movable in the housing co-axially and relative to each other between an open and closed position. A leakage space defined between the closure members by a drain outlet. One of the closure members is a slide piston having an end portion sealingly received in a recess provided in the other closure member. The wall of the recess has an annular groove which permits a seal cleaning flow of liquid between the surfaces of the seal provided on one of the closure members and the annular groove into the leakage space.

Abstract: The disclosure relates to a non-mixing valve intended for sealing between two conduits and comprising two mutually movable valve bodies which are disposed to realize a double seal against the seats located in an opening between the conduits. A leakage chamber is disposed between the two valve bodies for draining-off leakage between the conduits. The seal on the one valve body consists of an axial seal, and the seal on the other valve body cosists of a radial seal. Furthermore, the valve bodies, of which the one is disposed to accommodate the end of the other, are of such configuration as to balance pressure and pressure hammers in the conduits.