| 摘要 |
A novel self-tightening seal arrangement for a gate valve, parallel valve or the like. A stuffing box chamber containing sealing material is located within the valve head, which takes advantage of the internal pressure of the valve for improved sealing. A sleeve is provided upon the valve spindle and moves upwardly with the valve blocking element as the latter is raised to open the valve, continued raising of the blocking element forcing the sleeve to engage and compress the sealing material in the stuffing box chamber. Locking means are provided to prevent the sleeve from withdrawing as the valve is closed by lowering the blocking element, and the compression upon the sealing material is thus maintained. By fully raising the blocking element after the normal opening function of the valve and thus periodically increasing the compression upon the sealing material, the normal tendency of the material to lose its normal resiliency and sealing effect can be compensated for in a simple and effective manner.
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