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Old December 11th, 2005, 09:01 AM   #7
10baseT
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United Kingdom

10baseT is offline
 
Join Date: Nov 2005
Location: wrexham
Posts: 271
Well , I'm of the opinion it is the wrong way of doing the job anyway , what is the relationship of pressure (valve position) V flow ? what is the valve seat type , equal percentage , fast opening , linear ?
Again , I can't see what the pressure entering the tank has to do with it - and you have to be very careful that the liquid entering the tank doesn't cause surging and oscillation on the perceived pressure read by the level transducer .
Does it matter if the level rises and falls between two levels ? if not , simple on off control will work .
How many different levels are required by the operator ? and why ?
I personally would use an ultrasonic level detector if it was necessary to have many different levels in the holding tank .
Smoothing is one thing for the PV , but moving the transducer input to the PV every 0.5second ? I don't think so (just out of interest , are you sure that your coding makes sure that there is a value in the PV continuously , rather than just every 0.5 seconds ?

All in all , a good case for designing the system before you build it .
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