Hubventil für Verfahrensgas

摘要

A valve for process gas is of the screw plunger type with bellows seal for leakage protection, and the invention provides additional protection to enhance valve integrity in the event the bellows should fail, Such additional protection provides at least two seals in tandem for each of the two prospective leakage paths. At least one of each set of seals is operative between relatively fixed members rather than between a fixed and a movable member.