一个排放活门被安装在水箱底部。

A drain valve is located on the bottom of the tank.

发动机上，用来降低压气机压力的活门。

A valve on the engine for reducing pressure in the compressor section.

隔膜，用气压或液压操作的活门机构中的柔性部件。

DIAPHRAGM, A flexible part for operating a valve mechanism by pressure.