As transducers age, their original calibrations drift, becoming less reliable due to repeated loading and unloading, ageing components, and environmental conditions. Temperature is an important factor in the calibration process as this has a strong effect on how transducers behave which is explained here. Ideally, a transducer should be calibrated at the temperature that it will be used at.
The goal of calibration is to minimise any measurement uncertainty by ensuring the accuracy of test equipment. Calibration quantifies and controls errors or uncertainties within measurement processes to an acceptable level.
How often should I re-calibrate my transducers?
The best practice is for transducers to be calibrated annually. However, this is dependent on the acceptable level of drift.
A calibrated source that measures the same parameter as the transducer is required for re-calibration to be conducted.
Calibrating a pore pressure transducer using GDSLAB
Please refer to Helpsheet 142 - Entering transducer calibration data
Pressure controllers: using our FieldCal software tool to re-calibrate a controller
First, “Connect” to your GDS controller, then “Begin” calibration.
You will then be met with this screen, select “Least Squares Calculator”1.
For a 3MPa controller, the following pressure intervals are only an example of what you can choose. Set the pressure of the reference to 0, type 0 in the “Reference (kPa)”3 box and then select “Add”4. This will create the first calibration point. Repeat this for each pressure interval to the pressure limit and then go back down to 0.
The reference pressure is matched with the counts (ct) of the controller and a line is plotted to determine what pressure to display depending on the counts. For example, a two-point calibration matches 0kPa to 0ct and 1000kPa to 1000ct, this line will then interpret 371ct as 371kPa.
Once finished. Select “Calculate Least Squares Fit”5, this will provide you with the “Correlation Coefficient”6, the closer this value is to 1 the better as this is the linearity of the calibration. Then “Save”7 the calibration, select “Use”8 and then select “Store Calibration Permanently”2.
AdvDCS V2 (Calamari) systems
To re-calibrate transducers in systems based on AdvDCS V2 devices, please refer to the following page:
214 GDS Helpsheet - Change, update or create transducer calibrations in AdvDCS V2-based systems