7.4.2.2 O
2
sensor calibration
The O
2
sensor needs to be calibrated after each sensor service. Wait at least 30 minutes after
mounting a new membrane before re-calibrating. The sensor is in contact with either:
• Air at atmospheric pressure (In Air)
• O
2
at known concentration (Direct value). The gas can be dissolved or not.
In air calibration
This calibration procedure places the O
2
sensor in water-saturated air, to provide a known oxygen
reference against which to calibrate.
Dry the sensor thoroughly, before placing the sensor storage cap under tap water. Shake off any
excess water, but leave a few drops inside the cap. Verify that the screw-on protection cap is in place
on the sensor head. If you use a Dacron mesh inside the protection cap, make sure it is dry before
attempting to calibrate. Then, loosely place the storage cap back on the sensor, holding it in place
with a few turns of its collar.
Set the calibration parameters accordingly and press calibrate.
Direct calibration
This procedure calibrates the oxygen sensor against a liquid sample containing a known level of
dissolved O
2
flowing through the sample line.
The instrument displays the sensitivity of the sensor as a percentage of the sensitivity determined
when calibration was last performed.
Set the calibration parameters accordingly and press calibrate.
7.4.2.3 O
3
sensor calibration
The sensor is either in contact with:
• Air at atmospheric pressure (In Air)
• O
3
at known concentration (Direct Value). The gas can be dissolved or not.
The procedure is the same as for the O
2
sensor. In the case of the "In air" calibration, the sensor
measures O
2
during calibration. The O
3
coefficient is deduced taking into account how the sensor
behaves in O
2
. As a different voltage is used at the anode to measure O
2
and O
3
, the O
3
measurement takes a long time to stabilize. To facilitate the follow up after an "O
3
in air" calibration,
negative values can be displayed.
7.4.3 TC sensor calibration
7.4.3.1 Calibration of the measured gas
1. Before initiating a calibration process, the calibration parameters must be set by pressing on the
Modify button. The last calibration parameters are memorized, so this step can be ignored if the
correct parameters are already set. Similarly, if only the calibration value has changed, then this
can be updated directly instead of pressing the Modify button.
Option Description
Gas Phase Select liquid or gas (direct calibration only)
Gas unit type Partial, fraction or dissolved (dissolved is for calibration in a liquid only)
Gas unit The list of available units depends on unit type selected above.
Liquid Select as appropriate.
Value Enter the gas concentration according to the value in the calibration media.
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