Set Zero Calibration - Thermo Scientific Orion Star A210 Series Manual

Chapter 6 Using the DO/RDO Channel
|
68 Orion Star A210 Series Benchtop Meter User Manual
|

Set Zero Calibration

An Air (water-saturated air) calibration or Water (air-saturated water) calibration must be
completed before a Set Zero calibration can be performed.
Prepare a sodium sulfite solution by dissolving about 15.0 grams of Na
distilled water. Transfer the solution to a BOD bottle or flask and use plastic paraffin film to seal
the bottle. A small amount of cobalt salt can be added to the sodium sulfite solution to act as an
indicator and change color when the sodium sulfite solution no longer has zero oxygen content.
1. Press the f1 (cal) key to start the calibration.
a. If more than one channel is displayed in the measurement mode, press the p or q
key to highlight DO/RDO-Channel and press the f2 (select) key.
2. Press the p or q key to highlight Set Zero and press the f3 (select) key.
3. Prepare the DO sensor and zero oxygen solution and allow them to reach equilibrium.
a. Use plastic paraffin film to seal the open area between the DO sensor and vessel
containing the calibration solution.
4. When the DO sensor and calibration apparatus are ready, press the f3 (start) key.
a. If using a stirrer probe, the stirrer probe will start stirring when the f3 (start) key is
pressed and stop stirring when the reading stabilizes.
5. Wait for the dissolved oxygen value on the meter to stabilize.
a. 0.0% will be displayed for P2 when the reading stabilizes.
6. Press the f2 (cal done) key to save and end the calibration.
7. The meter will display the calibration summary and export the data to the calibration log.
Press the f1 (meas) key to proceed to the measurement mode or press the f2 (print) key to
export the calibration data to a printer or computer.
SO in about 250 mL of
2 3
Thermo Scientific