working principle

When the valve feeds water from the inlet end, the water enters the main valve control chamber through the microfilter, needle valve, and check valve, and then drains to the downstream through the ball valve. Since the needle valve opening degree is smaller than the ball valve opening degree, that is, the drainage speed of the main valve control chamber is greater than the water inlet speed, the control chamber pressure is lowered, and the inlet pressure acting on the lower end of the main valve disc opens the main valve to supply water downstream.

When the pipeline stops supplying water, if the downstream water starts to flow back, a part of the return water enters the main control room through the ball valve. Due to the check valve action, the return water cannot flow out from the main control room, causing the main control room to gradually increase pressure and slowly close the main valve. 

The main technical parameters