DI Water Centrifugal Pump Flow PID control

[Camcanpro]

Clarification

Thanks for the advice

In 4000L tank, the DI water will mix with other materials first, such as color, Sweeteners etc. So the conductivity can meet the meg meter requirement. Sorry for the confusion.

Also the meg meter is installed in a vertical pipe with the flow going upwards, and placed more than xxx pipe diameters from bends.

 

[Bit_Bucket_07]

I'm just having a hard time envisioning how the fluid flow under only the force of gravity could actually be as erratic as indicated by your PV graph.

I guess that I could see it if you were pumping into a closed vessel with a pressure relief valve intermittently releasing air from the receiving tank as the liquid level in the tank increased.

I would expect to see a much more consistent flow rate, even as I would expect a relatively consistent flow rate with the pump running and the control valve in a fixed position. Either your meter is lying to you, or something in your process is impeding fluid flow in a very random manner.


BTW: Although the power wiring should not be in the same conduit with your signal wiring, I don't think that electrical interference from a 120 VAC 60 Hz circuit would explain the deviation pattern seen in your flowmeter output signal graph.

Another BTW: Is the signal from the flowmeter stable when there is no flow?

 

[Calistodwt]

Magnetic flow meters can be installed in horizontal or vertical piping so long as the pipe remains full at the point of measurement.

Magnetic flow meters can be used to measure laminar or turbulent flow (i.e. they are not Reynolds number sensitive).

Is your control valve cavitating at all ?

Is your pump cavitating ?

What is you line size and control valve size?

Do you have a filter on your measurement in your PLC ?

Are there any limits set on your valve travel as the PV trend has some flat spots at some high and low values?