Principle of Differential Pressure Control Valve
P1 is the pressure of water supply, P2 is the pressure of backwater in the valve and P3 is the pressure of backwater outside the valve. When P1-P3 increases, the induction diaphragm moves the disc upward, reducing the flow area and increasing P2-P3, thereby maintaining P1-P2 constant, i.e. the pressure difference on the control system remains unchanged. Conversely, if P1-P3 decreases, the disc will move down, P2-P3 will decrease, and P1-P2 will remain unchanged. If P1-P3 remains unchanged, and the resistance within the controlled system changes, such as P1-P2 increases, the disc opens slightly, so that P2 returns to its original value, that is, P1-P2 remains unchanged. Therefore, this valve can adjust the pressure changes in the system outside the controlled system.