In this video, we are calibrating the EXO Optical Dissolved Oxygen sensor in percent saturation using Kor Software. You can also use the EXO Handheld or the Kor Mobile App.
Calibrating in DO percent calibrates all dissolved oxygen parameters, so you don’t have to do a separate calibration for mg/L. We recommend calibrating in DO percent for both ease and accuracy.
DO percent is a direct measurement from the sensor and goes into the DO mg/L calculation along with temperature and conductivity. So if you are measuring dissolved oxygen in mg/L, you want to make sure your temperature sensor is reading accurately, and your conductivity sensor is calibrated and ready to go.
As with every calibration, it is so important to make sure your sensors, sensor guard, wiper, and cal cup are all clean. For efficiency, you may decide to use a separate cal cup and sensor guard for calibration; that way, you know it is clean and it won’t negatively impact your calibration.
Now for this calibration, we are going to be calibrating in a 100% water-saturated air environment. We achieve this by placing a small amount of water in the cal cup and placing it over the sensors. It is important that you do NOT seal the cup as the cal cup needs to be vented to the atmosphere for it to become fully saturated.
If you prefer to calibrate in air-saturated water or if you want to do a 2-point calibration with a zero point, please refer to the EXO User Manual for details.
Ok, so we are going to put a small amount of clean water in the cal cup; about an inch of water or 3 cm is enough. You don’t want too much water in the cup because you don’t want the sensor submerged in the water. You want them above the water.
Before putting the sonde in the calibration cup, make sure there aren’t any water droplets on the DO sensor or the thermistor. You can dab them dry with a Kimwipe. Next, put on the sensor guard and insert the sonde into the calibration cup. And remember, do NOT over-tighten the seal around the cup!
Next, wait about 10 minutes for the cal cup to become 100% saturated and for the sensors to equilibrate. Then, using Kor Software or the mobile app, you will enter your true, local barometric pressure. If you are using the EXO handheld with a built-in barometer, this value will be populated automatically.
Next, we simply wait for the readings to stabilize. Kor software will indicate when your readings are stable, and you can see the actual temperature and DO readings in real time.
Once they are stable, we’ll go ahead and click apply. You will then see the calibration record so you can verify the calibration values. From here, you have the opportunity to redo the calibration point or proceed with completing the calibration. We’ll go ahead and complete the calibration.
And now our ODO sensor is calibrated and ready for use. Be sure to check out our other EXO University videos, and thanks for watching!