<6. Calibration Procesure>
6-1
IM 12J05D02-01E
6.
Calibration Procesure
Calibration of the dissolved oxygen analyzer is performed in the following situations:
• When a new dissolved oxygen sensor is installed.
• When the membrane is replaced and/or the electrolyte solution is replaced
• When the measuring error after cleaning exceeds the acceptable deviation from reference
method
• When error message E12 or E16 indicates the need for maintenance
NOTE
When a new sensor is installed, when the membrane is replaced, and/or the electrolyte solution
is replaced, it may take some time for the electrodes to stabilize due to the initial electrolysis. In
particular, a zero calibration should be performed after the electrodes are exposed to the air or
immersed in sample water for about half a day. When the sensor cable terminals 13 and 15 are
shorted together before installation, the time for the zero point to stabilize can be reduced.
NOTE
It may take a long time for the electrodes to stabilize in the first electrolysis just after installing
the DO30G sensor or other galvanic sensors and polarographic sensors, or after replacing the
membrane or electrolyte solution. The zero calibration in particular should be carried out after
leaving the sensor operating in air or measurement liquid for about half a day. The time for
stabilizing the zero point can be reduced by shorting the terminals 13 and 15 of the sensor cable
before installation.
6.1 General
6.1.1
Calibration methods
There are three methods for calibration of the EXA dissolved-oxygen analyzer: air calibration,
water calibration and manual calibration.
l
Air calibration
This is the most common and easiest way to calibrate the analyzing system. The calibration is
done in AIR.CAL mode in maintenance level.
l
Water calibration
This is the traditional way to calibrate dissolved oxygen analyzers in laboratory environment. .
Accurate results can be obtained if the calibration is performed carefully. The water calibration
may include a zero calibration if so selected in service code 21. Normally only a zero check is
performed without calibration, since a good sensor has no zero signal.
Always select 1 in service code 21 for the DO70G optical dissolved oxygen sensor.
Water calibration is not possible in salt water unless salinity compensation is activated in service
code 04. The calibration is done in H2O.CAL mode in maintenance level.
NOTE
In normal industrial environment better results are obtained with air calibration, which is therefore
the recommended method.
9th Edition: Aug. 05, 2015-00
Summary of Contents for EXA DO402G
Page 9: ...Blank Page...
Page 23: ...Blank Page...
Page 77: ...Blank Page...
Page 81: ...Blank Page...
Page 85: ...Blank Page...
Page 87: ...Blank Page...
Page 95: ...Blank Page...