In this video we are calibrating the EXO Conductivity/Temperature sensor for Specific Conductance in microsiemens per centimeter using Kor Software. You can also use the EXO Handheld or the Kor Mobile App.
Now, there are two different conductivity temperature sensors available for your EXO sonde. One is designed to be easily cleaned by the EXO Wiper, extending your deployments. The other CT sensor provides highly accurate data, it’s just not designed for wiping. Here, you can see how effectively the wiper can cleans the wiped CT sensor.
Before calibrating, we recommend checking the temperature sensor against a NIST-traceable thermometer since specific conductance is temperature compensated and therefore requires accurate temperature measurements.
Now, calibrating one conductivity parameter automatically calibrates all other conductivity parameters. So, we are going to be calibrating specific conductance for both ease and accuracy. But before proceeding, make sure your conductivity sensor is clean. This can be done by checking the measurement in air. A clean conductivity sensor should read 0 in air.
Also, it is important to make sure your sensors, sensor guard, and cal cup are all clean. And if you have a wiper installed, make sure that the wiper brush and brush guard are also clean.
For efficiency, we suggest using a dedicated cup and guard just for calibration.
If you are using an EXO cal cup, make sure to fill to the second line from the bottom so that the conductivity cell is fully submerged in the conductivity solution.
We suggest using a standard that is closest to your expected field measurements. Here we are going to use a 1,000 µS/cm standard, which is equal to 1 mS/cm. Now, let’s immerse the sensor in the solution.
Once the sensor is immersed, move the sonde around and give it a few taps to make sure there are no bubbles trapped in the conductivity cell. If you have a central wiper installed, go ahead and run it to help clear any bubbles.
In the software, we are going to go ahead and click calibrate for specific conductance. Now, if the measurements seem low, double-check that you have enough solution to cover the electrodes. This means enough solution to cover the holes on the side of the non-wiped version or enough solution to completely cover the measurement channel of the wiped version.
Since we are calibrating specific conductance rather than conductivity, you can simply set the calibration value to the solution’s value at 25 degrees C. In our case, we are going to confirm 1000 µS/cm.
Kor software will indicate when your readings are stable, and you can see the actual temperature and conductivity measurements in real-time. You want to make sure both of these parameters are stable before proceeding.
Once the measurements are stable, go ahead and click apply. Here, you can double-check the calibration values. At this point, you can choose to redo the calibration point or proceed with completing it. I’ll go ahead and complete the calibration. Next, you will see the calibration summary, which is stored in the cal record. The calibration data looks good, and the cell constant is within range for a good QC score.
And now our conductivity sensor is calibrated and ready to use. Be sure to check out our other EXO University videos, and thank you for watching!