Certain corrective actions of this guide may not be feasible with the Compact Ball Valve (sealed unit).

对于紧凑型球阀(密封装置)，本指南的某些纠正措施可能并不可行。

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Group 31 compact valve actuators are designed for coupling to small quarter-turn ball and butterfly valves.

该小型阀门执行器专为小回转球阀，蝶阀设计的。

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