Copper corrosion meter

[nibola]

Hi
I have a corrosion meter, a 9030 Plus corrater instrument that measures the corrosion of a copper probe in mils per year. This corrosion meter is connected to a Web Master Water Controller, that reads the 4-20mA signal.
So there are two displays, one for the corrater on the other one for the controller
On the configuration panel of the corrator I can change the “Probe rate 4-20 LOOP F/S”. This value defines the full scale for the 4-20mA. By default is 20MPY.
If I change this value to 1 for instance, the reading in the corrater stays the same but the reading in the controller is multiplied by 20.
I guess that this is changing the scale of the 4-20 signal. My questions are:
What is this value for? I mean, how do I know which is the correct value?
It is confusing also that when I change this value, the readings on the corrater stays the same and the readings on the controller change.
As far as I know, the only way to calibrate the system is to replace the copper probes.

Any help regarding this corrosion meter will be highly appreciated

Best regards

 

[Compositepro]

TRFM applies here. My guess is that is serves both as a scaling factor and as a calibration factor. Replacing the probe is not a calibration procedure. The meter on the controller may only be a current indicator, whereas the 4-20 signal can be calibrated in units of mils per year.

 

[cloa]

You should ask in the Corrosion Engineering Forum- much more relevant (their bread and butter). Just with my limited experience of online corrosion measurement- that probe description doesn't sound right- its more likely that its a linear polarisation device which is attached to the process pipe( measuring its corrosion) and probe is a reference probe. Such a probe needs considerable setup and calibration for corrosion environment so that it measures the corrosion rate right assuming that its even useful (not useful if considerable localised corrosion occurs). The controller is just to improve the output to record.

http://www.eng-tips.com/threadminder.cfm?pid=1529

Use translation assistance for Engineers forum

Note the rules include No Student posting

 

[nibola]

Thank you Compositepro and cloa

You are right that replacing the probe is not a calibration procedure, but I guess that installing new probes is a way to check that the corrosion rate goes down to near a zero value and that the meter is working fine. I don’t know any other way to do it.

And you are right that the readings do not make much sense. Before going ahead trying to figure out why do I have that corrosion rate, the first thing I want to do is to make sure that the signals and the readings I am having are correct. And then from there, to decide whether the values are good enough for me or not.

What I don’t really understand is why changing the parameters in the corrater, the values in the same corrater do not change and the values in the controller do change. I don’t understand what is that useful for.

Thanks for telling me about the corrosion engineering forum, I didn’t see that one before, I will post my doubts there as well

Thanks again!