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Calibration
6 CALIBRATION
CALIBRATION OF THE TEMPERATURE SENSOR
6.1
The temperature sensor is an accurate NTC. It has precise tolerances and, therefore, does not
require calibrating.
CALIBRATING THE O
6.2
Since the oxygen sensor only experiences a very slight amount of wear as a result of exposure,
regular calibration is not necessary. It has been empirically determined that after 1 million
exposures (equal to 1 million O
ppb and that at higher O
There is a light pulse counter integrated in the software, which counts the number of light
exposures. When 1 million exposures have taken place, the warning "Calibrate or replace the O
sensor" will be displayed and the sensor must be calibrated or replaced. The warning symbol will
be displayed as a reminder.
After successfully calibrating the sensor, the light pulse counter will be reset and the warning
symbol will no longer be displayed.
The following two principle methods are described to calibrate the oxygen sensor:
1. One point calibration
This method is recommended if a high accuracy for higher oxygen concentration is
required.
2. Calibration with two gasses
This method is recommended to ensure the specified accuracy over the whole oxygen
measuring range.
CALIBRATION FREQUENCY
6.2.1
It is recommended to recalibrate the sensor after 1 million exposures. If the default sample time
(1 measurement/30 seconds) is used, the sensor must be recalibrated once a year, assuming that
the sensor is in operation 24 hours a day, seven days a week. If a shorter sample time is used, the
sensor will reach 1 million light exposures sooner and will, therefore, require calibration sooner.
ONE POINT CALIBRATION
6.2.2
For most applications in the low oxygen measuring range a calibration of the zero point is
sufficient.
Preparation:
The calibration gases must be dry.
The zero-point calibration should be carried out using a gas with a certified oxygen
content of ≤ 0.001%. The use of nitrogen or carbon dioxide with a purity of 99.9990%
(Class 5.0) is reccomended.
33
SENSOR
2
measurements), the O
2
values, no deviation is detectable.
2
deviation from the zero point is just 5
2
9065 Luminescent Dissolved Oxygen Analyzer
2
Waltron User Manual
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