Butterfly valve is also called a flap valve, is a simple structure of the regulating valve, but also can be used for low pressure pipeline medium switch control.

蝶阀又叫翻板阀，是一种结构简单的调节阀，同时也可用于低压管道介质的开关控制。

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These valves use a screw type valve instead of a simple flap, and they have a pressure regulating mechanism that will vent water to the ground if the intake pressure exceeds a set level.

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