A disk turning on a diametrical axis inside a pipe, used as a throttlevalve or damper.
节流阀，减压阀：管道内沿直径中心轴线上的圆片状旋钮，用作节流阀门或阀门。
2
Butterfly valve through the valve shaft rotation to drive the rotation of a disc-shaped disc, to open and close a valve, cut off from the main pipe and throttle with.