US Patent 7905253 Double seat valve

The invention relates to a double seat valve with cleanable seats, the valve including first and second closing elements (3, 4) and a leakage cavity (5). An intermediate seal (8) seals the closing elements (3, 4) in their opening and closing movements and in the open position against each other, is arranged in the second closing element (4). The second closing element (4) abuts in its closed position at a transition area (2e, 2e*) with a stop face (4e) arranged at a front face of a cylindrical lug (4*) and that directly adjacent to a first seat (2a, 2g), a central recess (4d) is provided in a front face of a second cylindrical lug (4*).