The automatic control valve of booster pump is divided into three parts: main valve body, diaphragm control room and bypass pipe. With the diaphragm as the boundary, the upper cavity above the diaphragm is connected with the drainage pipe, and the lower cavity below the diaphragm is connected with the valve inlet pipe. The small valve plate is fixed on the valve rod, and the large valve plate slides up and down on the valve rod. When the motor is started, the pressure at the valve inlet increases gradually, and the pressure water:
1) When the force pushing the large valve plate upward is generated, the valve cannot be opened immediately (because there is back pressure in the upper chamber of diaphragm control).
2) The pressure enters the lower chamber of the diaphragm control chamber through the bypass pipe. With the increase of water inflow into the lower chamber, when the pressure in the lower chamber is greater than that in the upper chamber, the pressure water in the lower chamber pushes the diaphragm upward. At this time, the small valve plate does not exert pressure on the large valve plate.
3) The large valve plate has a force to push it upward. Under the action of these two forces, the valve will gradually open, so as to achieve the purpose of light load, closing and slow opening when starting the pump. In case of sudden power failure, accidental pump shutdown or normal pump shutdown, the pressure water flow velocity at the valve inlet decreases, and the large valve plate also decreases. When the flow velocity is zero (i.e. when the flow velocity at the water inlet is zero), the large valve plate closes rapidly due to its own gravity (for 3S ~ 5S), which can prevent most of the water from flowing back. At this time, a water pressure difference is formed in front of and behind the valve, On the one hand, the pressure water is relieved through three pressure relief grooves at the bottom of the small valve plate.
4) The pressure water enters the upper chamber of the diaphragm control room from the bypass pipe (this process is a pressure absorption chamber, which can effectively absorb part of the water energy). When the pressure water in the upper chamber is greater than that in the lower chamber, the pressure water pushes the diaphragm down. When all the pressure water in the lower chamber is squeezed out, the small valve plate slowly drops and returns to the standby state. The slow closing time in this process can be adjusted (3S ~ 150s), At that time, all valve plates have been closed without leakage. Because it has four water hammer elimination functions such as quick closing, linear pressure relief, pressure suction chamber and slow closing, there is no sound during shutdown, and the effect is very good.