In any fluid handling system, valves are the controlling element: starting or stopping flow, regulating or throttling flow, preventing backflow, or relieving and regulating pressure.

在任何流体处理系统中，阀门是作为控制装置：启动或停止流体流动，对流体进行调节或节流，防止倒流，或释放和调节压力。

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First: to act as an automatic non-return valve by preventing a backflow of steam from the main steam header to the boiler.

首先，能过作为一个自动逆止阀，防止蒸汽从主蒸汽加热器上倒流到锅炉里。

youdao

First: to act as an automatic non-return valve by preventing a backflow of steam from the main steam header to the boiler.

首先，能过作为一个自动逆止阀，防止蒸汽从主蒸汽加热器上倒流到锅炉里。

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