Dissolved Oxygen Calibration; Water Saturated Air Calibration - Thermo Scientific Orion Versa Star Pro User Manual

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Dissolved Oxygen Calibration

Note: A polarographic DO probe must be polarized prior to use. The probe is continuously
polarized when connected to the meter. If the polarographic DO probe is new, has been
serviced or has not been connected to the meter: connect the probe to the meter, power on the
meter and wait 30 minutes for the probe to polarize.
The Versa Star Pro meter with RDO/DO module offers the following calibration options:

Water Saturated Air – This is the simplest and most accurate method and uses the
calibration sleeve included with most DO probes. For best accuracy, the calibration
temperature should match the expected sample temperature. Moisten the sponge in the
calibration sleeve with distilled water and insert the probe into the sleeve. A BOD bottle can
be used with just enough distilled water to cover the bottom without touching the probe.

Air Saturated Water – This method uses water that is 100% saturated with air. Bubble air
into a water sample for an extended period, preferably overnight.

Manual (Winkler) – This method uses a water sample with a known concentration of
dissolved oxygen and is typically used to calibrate the DO probe to the value achieved by a
Winkler titration. Due to possible titration errors, this method is inherently less accurate.

Set Zero – This method uses an oxygen free solution to add a zero point to an existing
Water Saturated Air or Air Saturated Water calibration. This calibration is generally
recommended when measurements are below 10% saturation or 1 mg/L.
Prepare the DO probe according to the instructions in the probe user manual. Connect the
probe and any other electrodes to be used to the module inputs on the selected channel.
In the measurement mode, press the channel key until the channel with the RDO/DO module
with DO probe connected is shown.

Water Saturated Air Calibration

1. Press the f1 (Cal) key to start the calibration.
a. If more than one channel is displayed in the measurement mode, press the  or 
key to highlight the desired channel and press the f3 (Select) key.
2. Press the  or  key to highlight Water Saturated Air and press the f3 (Select) key.
3. Prepare the DO probe and calibration sleeve and allow them to reach equilibrium.
4. When the DO probe and calibration sleeve are ready, press the f3 (Start) key.
5. Wait for the dissolved oxygen value on the meter to stabilize and press the f2 (Accept)
key.
a. With a polarographic DO probe, 102.3 % will be displayed when the reading stabilizes.
b. With an RDO optical DO probe, 100.0 % will be displayed when the reading stabilizes.
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Chapter 6 RDO/DO Measurement Module
Orion Versa Star Pro Meter User Manual
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