Calibration a dew point measurement system


Thread Starter


We have a GE dewpoint measurement equipment installed on the outlet gas pipeline of our plant, I would need to have more information about the ways that we could make sure that the reading is correct.
I do appreciate your concern and advice.
Do you have the instruction manual for the device?

Are there any instructions in the manual about verifying calibration/output?

These are usually very difficult to calibrate without a lab set-up which can flow air of a known humidity over the sensor.

I believe the best way is to send the device to a proper calibration lab, unless your site has a very good instrumentation shop/lab.
Hi there,

Not much you can do to verify their accuracy in the field I’m afraid. I suggest you take the original data-sheet supplied with the analyzer/transmitter and see if there is some calibration constants that you can check. Consult the manual since they might have a calibration validation procedure in there. It will be some constants values you can check on the display or some voltages you can measure on the PCB.

Something you can check is the mA outputs according to the factory calibrated zero and span values. If it is dew point you have on the output it should have a facility on the matrix of the transmitter to simulate the 0 to 150 degrees C or whatever your factory calibration should be according to the data sheet.
You can then make adjustments on the transmitter's output to make sure the correct Z/S dew point values (as per data sheet)give a accurate 4 to 20 mA output.

I know the manufacturer can also supply you with various saturated salt solutions that you can use in a lab or w/shop environment to verify the accuracy of the transmitter so get hold of them and ask them about that.

Another possibility is to buy a hot factory calibrated standby identical to the installed unit and just change it out with this spare one while you send the other one for the calibration verification to the factory one a year or once every two years. There might be a limited sensor shelf live or special sensor storage requirements involved, so speak to the supplier and see if this might be possible option.