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Calibrate an Optical Dissolved Oxygen Sensor

Improve the accuracy of the Wireless Optical Dissolved Oxygen Sensor by calibrating the saturation measurement.

Before you start

Calibrating an Optical Dissolved Oxygen Sensor will require calibration standards with 0% and 100% dissolved oxygen saturation. Either water-saturated air (recommended) or air-saturated water can be used for the 100% dissolved oxygen saturation standard.

  • 100% dissolved oxygen saturation standard (water-saturated air)

    Moisten the sponge inside the sensor's rubber boot with distilled water. Loosely cover the sensor cap with the rubber boot and let the sensor acclimate for about 15 minutes. Leave the boot on the sensor cap during calibration.

  • 100% dissolved oxygen saturation standard (air-saturated water)

    Connect an air stone to an air pump and place the air stone into a beaker of water. Allow the air pump to run for about 10 minutes.

  • 0% dissolved oxygen saturation standard

    Pour 150 milliliters of distilled water into a beaker. Dissolve sodium sulfite, sodium bisulfite, or potassium sulfite into the water until a small amount remains undissolved in the bottom of the beaker.

Calibrate the sensor using one standard

Use only the 100% dissolved oxygen saturation standard to calibrate the Optical Dissolved Oxygen Sensor.

  1. Connect the sensor to SPARKvue.
  2. Create a display with DO2 Saturation as one of the measured quantities.
  3. From the Experiment Screen, click the Live Data Bar for DO2 Saturation from the bottom left and select Calibrate measurement.

  4. Ensure that the Optical Dissolved Oxygen Sensor is selected in the first box and DO2 Saturation (%) is selected in the second box. Select 1 point (Adjust Slope Only) in the third box, then click Continue.

    Start New Calibration (1 Point)

  5. Place the sensor into the 100% dissolved oxygen saturation standard, immersing the metal sensor body in the standard.

  6. Enter 100 into the Standard Value box, then click Set Calibration.

    Calibrate ODO Sensor (1 Point)

  7. Review your new calibration, then click OK to finish.

Calibrate the sensor using two standards

Use both the 0% and 100% dissolved oxygen saturation standards to calibrate the Optical Dissolved Oxygen Sensor.

  1. Connect the sensor to SPARKvue.
  2. Create a display with DO2 Saturation as one of the measured quantities.
  3. From the Experiment Screen, click the Live Data Bar for DO2 Saturation from the bottom left and select Calibrate measurement.

  4. Ensure that the Optical Dissolved Oxygen Sensor is selected in the first box and DO2 Saturation (%) is selected in the second box. Select 2 point (Adjust Slope and Offset) in the third box, then click Continue.

    Start New Calibration (2 Point)

  5. Place the sensor into the 100% dissolved oxygen saturation standard, immersing the metal sensor body in the standard.

  6. Under Calibration Point 1, enter 100 into the Standard Value box, then click Set Calibration.
  7. Transfer the sensor to the 0% dissolved oxygen saturation standard.

  8. Under Calibration Point 2, enter 0 into the Standard Value box, then click Set Calibration.

    Calibrate ODO Sensor (2 Point)

  9. Review your new calibration, then click OK to finish.

Set the salinity constant

The salinity of water can have an effect on the dissolved oxygen measurement. To account for this effect, a value can be entered for the salinity of the water sample.

Tip

Use the PASPORT Salinity Sensor (PS-2195) to obtain a precise salinity measurement.

  1. Connect the sensor to SPARKvue.
  2. Create a display with DO2 Saturation as one of the measured quantities.
  3. From the Experiment Screen, click the Live Data Bar for DO2 Saturation from the bottom left and select Configure Sensor.

  4. Enter a value in units of ppt into the Salinity box, then click OK.

    Salinity Constant