5.3 Dissolved Oxygen Calibration – Zero Calibration
A zero calibration can be performed to update the sensor’s signal offset. As supplied, the sensor is
factory calibrated and this value is stored in the internal electronics, but the operator can perform this
calibration as needed. Use the following procedure to perform a zero calibration on the Trace DO
sensor.
1.
Enter the calibration menu on the AV38 Remote Display (see the AV38 user guide for detailed
information on the various menus in the user interface).
2.
Press the ENTER key from the ZERO calibration menu to initiate the calibration process. When
the temperature calibration procedure is started, the analog output is placed into hold mode.
The user is prompted to prepare the sensor. The sensor value is dynamically updated during
this step.
Thermo Scientific AquaSensors
™
AquaTrace
™
Trace DO System User Guide
22
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Calibrate
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Zero
MENU ESC ENTER
3.
Remove the Trace DO sensor from sample chamber.
4.
Rinse the sensor head off with clean water. Shake any excess water off the tip of the sensor.
5.
Fill a beaker approximately ½ full with zero solution. Zero solution can be prepared by mixing
13.0 grams of sodium sulfite (Na
2
SO
3
) with 1.0L of deionized water. Observe all safety
requirements when mixing and working with the zero solution. Suspend the sensor over the
beaker with the tip of the sensor sits immersed at least one-inch deep in the zero solution. Allow
the sensor to acclimate and stabilize. In order to reach a stable zero it may be necessary to
allow the sensor to stand for up to twelve hours depending on the oxygen level in the sensor
prior to the calibration.
6.
After the unit has stabilized press the ENTER key to proceed with the calculation.
1.0 ppb
Sensor ready?
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MENU ESC ENTER
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