The process system is a juice pasturiser heat exchanger...

In short I have discovered that the steam valve is fully closed when the controller indicates 57% open. In principle, how do you scale the valve so that it is closed at 0% and fully open at 100% ?

(I will find out the valve type tomorrow and post it here...)

Thanks,
Mick

 

I think the controller indicator acts as the program. please find out the scaling block program and analysis it. then change the upper limit and lower limit to your desire limits (like 0% and 100%). probably now it is programed to indicate lower limit as 57%.

Bye
Reminder

 

You could have a calibration mismatch between the I/P or the positioner.

4-20mA might not be ranged for 0-100% output of either the I/P or the positioner.

Carl

 

I have a jumo 500 controller. it operates a steam modulating valve.
I have looked at the valve during normal Process Operation and it is physically opening aprox 45% (Maybe a bit less.)

As I said, the Jumo output indication icon and numerical display range from 57 - 60 %

I don't want the valve to open any more, I just want the scale to be realistic and read 0 - 45%

How and where do I scale the analogue as you say Carl?