| 摘要 |
The valve includes an inflatable seal element (86) located in the housing seat and a gas-pressure-purge arrangement (116, 118, 123, 124, 111, 112). The inflatable seal element (86) is inflated by means of pressurized fluid to grow in size and close up clearances between gate (50) and seat, thereby establishing a gas-tight seal between the two parts, at will. This can be done, for example, after the valve has been operated to close (slide gate (50) driven into the valve housing) and when a gas-pressure-tight seal is desired. Prior to this event, the gas-pressure-purge arrangement (116, 118, 123, 124, 111, 112) is activated to blast-off solid particles from the gate surfaces where these make contact with the inflatable seal element (86). Furthermore, the inflatable seal element (86) can be deflated to shrink in size, thereby providing increased clearance between gate (50) and seat, when desired. This can be done just prior to the moment when the gate (50) is to be operated (driven out of the housing) to open the valve. |
