embarrassing question regarding PID tuning

[ndzied1]

Do you have a feedback? I'm thinking carwash and things being very simplified they may not include an expensive device like a flow meter. Or maybe if the chemicals are very expensive then maybe they do?

Does the metering valve stay where it is after you stop pulsing?
OR
Do you send a constant string of pulses where the frequency determines the opening of the metering valve?

These are two different scenarios requiring different types of control.

 

[ganutenator]

Yes on the flow meter.
I am awaiting info on the valve.
All I know that uses pulse width modulation at this time.