Double seat valve with leak control

Double seat valve with leak control comprising a housing, a first valve disc located within said housing, an axially extending first shaft connected to said first valve disc, first means connected to said first shaft for movably displacing said first valve disc in the axial direction of said first shaft between a closed position with said first valve disc in sealed contact with said housing and an open position with said first valve disc spaced out of surface contact with said housing, a second valve disc located in said housing opposite said first valve disc, an axially extending second shaft connected to said second valve disc with the axes of said first and second shafts disposed in parallel relation, second means connected to said second shaft for movably displacing said second valve disc in the axial direction of said second shaft between a closed position with said second valve disc in sealed contact with said housing and an open position with said second valve disc spaced out of contact with said housing, said first valve disc being displaceable by said first means into the open position wherein said first valve disc is movable into contact with said second valve disc and said first and second valve discs being shaped to define therebetween a hollow space, a leakage liquid line being open at one end to said hollow space and at the opposite end to the exterior of said housing, wherein the improvement comprises that said first and second shafts being in general axial alignment and being spaced apart in the axial direction, said first and second valve discs being in spaced relation when each is in the closed position with said first valve disc being movable from the closed position toward said second valve disc into the open position and said second valve disc being movable away from said first valve disc in the closed position when said second valve disc is moved from the closed position into the open position, a spring biasing said second valve disc into the closed position, said first means includes a first adjusting device for moving said first valve disc into the open position and into contact with said second valve disc and for moving said second valve disc into the open position against the biasing action of said spring, said first means also includes a second adjusting device operable separately from said first adjusting device for moving said first valve disc independently of said second valve disc into the open position with said first valve disc spaced out of contact from said second valve disc and forming in combination with said housing an annular gap open to the space between said first valve disc in the open position and said second valve disc in the closed position, and said second means includes a third adjusting device operable separately from said first and second adjusting devices for moving said second valve disc independently of said first valve disc against the biasing action of said spring into the open position forming an annular outlet opening between said second valve disc and said housing opening to said hollow space with said first valve disc in spaced relationship to said second valve disc so that the area of the outlet opening is not greater than the transverse cross-sectional area of said leakage liquid line open to said hollow space.