| 摘要 |
A valve actuator includes a valve body, a valve member comprising a shaft, and a piston connected to the shaft, with the valve member being movable by operation of the piston. The valve body comprises a valve chamber that provides fluid communication between an inlet passage and an outlet passage. The shaft is disposed in and extends through a sealed chamber, the sealed chamber being sealed at one end from the valve chamber and at another end from a piston chamber, and a vent that extends from the sealed chamber to an external surface, wherein the shaft extends axially in both directions past sealed ends of the sealed chamber.
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