1, a simple flowmeter can't adjust the flow because it has no actuator.

2. The flow can be automatically adjusted by three parts: flowmeter, PID regulator and regulating valve.

3. Input the flow value you want on the PID regulator, which controls the opening of the regulating valve to regulate the flow, and the real-time flow signal detected by the flowmeter is fed back to the PID regulator.

The three forms a closed-loop control loop, thus realizing accurate control.