The flow value in the pipeline is controlled by the change of the opening size of the main
valve disc and can be stabilized at a set value. The size of the main disc switch and the opening is controlled by the size of the pilot
valve. The media pressure is taken from the downstream side of the throttle plate plus the spring force and the pressure taken from the upstream side of the throttle plate acted on the lower part of the diaphragm respectively. When the flow rate and pressure on both sides of the throttle orifice plate change, the pressure acting on the lower part of the diaphragm will no longer balance, the diaphragm deformation, the opening of the guide valve change, and the opening of the main valve will also change accordingly, so that the flow in the main road will return to the original set value.