Firstly there's the issue of valving.

首先有问题的汽门。

All necessary valving is included also.

所有所需要的瓣膜也包括在内。

Periodic pressure undulation may be incited by fast valving control.

使用快关调节阀控制能激励周期蒸汽压力脉动。

Do not expect one type of valve to perform all the valving jobs in a system.

不要期望一种类型的阀门能够在系统中实现所有的阀门功能。

Do not expect one type of valve to perform all the valving jobs in a system.

不要指望一种阀门能够担当整个管道系统内的所有功能。