Second guessing myself here, need someone to either tell me I'm wrong or confirm that my thinking is correct please.
I have an equal-percentage characteristic control valve and I need to control differential pressure across it. This is a secondary control mode. The primary mode is control based on flow rate (equal-percentage -> linear installed characteristic, so flow rate is linear with valve position, ideal for PID). When I have to do dP control, PV should be the square root of dP, correct? Because dP is proportional to flow rate squared, so I should sqrt dP in order for it to work with a PID loop properly.
I have an equal-percentage characteristic control valve and I need to control differential pressure across it. This is a secondary control mode. The primary mode is control based on flow rate (equal-percentage -> linear installed characteristic, so flow rate is linear with valve position, ideal for PID). When I have to do dP control, PV should be the square root of dP, correct? Because dP is proportional to flow rate squared, so I should sqrt dP in order for it to work with a PID loop properly.