| 摘要 |
A seal for a shut-off device moved in a rectilinear manner, which is switched from a closed to an open position and vice versa so as to shut off material flows. The seal is formed of metallic components which define a pressure chamber to which external pressure can be applied to achieve seal tightness. Employing only metallic components makes it possible to use the seal in a wide temperature range and under conditions of exceptional wear caused by either frequent actuation or the composition of the flowing medium. The sealing system includes a shut-off device (1) against which a movable seat (5) forms a seal. The seat is connected to the tubular casing (2) in a pressure tight manner, and the casing in turn is connected to a flange (3). The assembly is connected to a housing (8) by a flange (6) and is sealed by seal (7). Membranes (9, 10) and support plate (14) form a pressure chamber (11) to which pressure Ps is applied through connecting nipple (13) and bores (12). Pressure Pb acts in pressurized space (69), and pressure Pg in pressurized space (70). The pressure duct inside casing (2) between connecting nipple (13) and bores (12) is formed by plate (15) which is connected to the casing in a pressure tight manner. Membrane (9) has a wear-resistant coating where it contacts the shut-off member (1). Support plate (14) constitutes a radial guide for membranes (9, 10) to prevent plastic deformation due to frictional forces during actuation, and it axially limits displacement during changes in direction of the pressure when the shut-off device is closed. When no pressure Ps is applied to membrane (9), it rests flat against the annular surface of support plate (14), so the surface pressure against shut-off member (1) is reduced and the membrane is not at risk of permanent deformation as the shut-off member is actuated.
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