| 摘要 |
The invention relates to a double seat valve with cleanable seats comprising two closure members which are placed in series and which can be moved in relation to one another, in accordance with the generic part of claim 1. The aim of said double seat valve is to provide a double seal with a tight leakage cavity in relation to the valve housing part which is closed off by the second closure ember when the seat of the first closure member is being cleaned, said first closure member being ventilated across the width of the gap, along its seat surface, in accordance with the sealing concept of a double seat valve. To this end, the end section of the sliding piston (4) has two axially arranged radial sealing agents (6 and 7) in relation to its longitudinal axis. Outlets (4b) are provided in said sliding piston (4) between said sealing agents. Said outlets connect the area surrounding the sliding piston (4) to the leakage cavity (11) on the outer covering side. When the double seat valve is closed, both sealing agents (6, 7) are accommodated tightly in the cylindrical valve seat surface (3a) and when open, said sealing agents are taken into the recess (9). When the sliding piston is in the seat cleaning position, it is shifted towards its open position in such a way that the outlets (4b) are connected to the valve housing part (2; 1) adjacent to the seat surface which has become free, thereby ensuring that the sliding position (4) sealing agent (7) on the leakage cavity side in the cylindrical valve seat surface (3a) remains tight.
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