dear all.
i have aproblem in pressure control that i was using electronic prssure transducer type SMC :EIT 2010-O1FB with o/p (0.005- 0.1)bar with current control (4-20)mA and i got another type of transducer JOHNSON TRANSDUER 80004 with same charctristics but the problem is when fixing new one pressure (which control temperature throuh oil valve) not stable and temperature is variation is too much .

i need to know how to adjust itas i tried with manual but not coming with me .
thanks

 

A Johnson Controls EP-8000-4 is a high volume I/P, 4-20mA electronic to 3-15 PSI (0.21 to 1.05 bar) pneumatic transducer converter.

The I/P is a dumb device. It is not a controller. It makes no control decision. It merely converts an analog 4-20mA to a corresponding pneumatic signal.

Its user guide is here:
http://cgproducts.johnsoncontrols.com/MET_PDF/216370.PDF

The first thing to do is to determine whether this unit will span your desired range. Page 6 describes the minimum spans necessary under "calibration". Your former device was 0.005 - 0.1 bar. It isn't clear is that's your desired range and if so, over what electronic input span.

The reason these things come spanned the way they do from the factory is that 90% of all installations use these default settings. I'd question why you want a 0.005-0.1 bar signal. Is the actuator really setup to respond over that range?

Assuming you can get a suitable span for your actuator, your description of the problem is "pressure (which control temperature throuh oil valve) not stable and temperature is variation is too much."

Since you don't provide any details of your control scheme, I'll reference Figure 14 on page 6 of the EP-8000 manual which shows a heating control application.

The I/P does NOT control the temperature through the oil valve. Your controller (whatever it is) controls the valve by creating a 4-20mA output which drives the valve through the I/P.
An "electronic controller is marked on in Figure 14. You must have something functionally equivalent.

I'd recommend that you examine your controller for an adjustment labelled gain or PB or Prop band.

If it's labeled PB or Prop Band, increase the value.
If it's labeled gain, decrease the value.

Either action will make the control output less sensitive and reduce the instability.

David