H74.0.14.6C-05
Operating Manual GMH 3692
page 9 of 12
7 Calibration of the Sensor
In order to compensate for ageing of the sensor, the sensor has to be calibrated at regular intervals.
The device is equipped with an easy-to-use calibration functions.
We recommend to calibrate the sensor at least all 7 days, or to get maximum precision, before each
measuring series.
7.1 One Point Calibration ('
(AL 1-PT
')
The calibration adjusts the sensor to the oxygen content of the atmosphere (20.95%). Therefore simply
expose the sensor to the ambient air (sufficient ventilation in closed rooms has to be ensured)
Start calibration: press
-key for 2 seconds
The display will show '
A,R
, and as soon the values for oxygen and temperature are stable, the
calibration will be finished
Then the electrode state resulting of the successful calibration will be shown for a short time (evaluation in
10% steps: xx%
ELE[
).
7.2 2 / 3-Point Calibration ('
(AL 2-PT
,
(AL 3-PT
')
The sensor will be automatically calibrated to the oxygen content of the atmosphere (20.95%) and one or two
additional concentrations. As reference gases usually Nitrogen (0% vol O
2
) or pure oxygen are used
1. Start calibration: press
-key for 2 seconds
2. First calibration reference: (Pt.1)
As first reference at a 3-point calibration, the zero reference has to be applied (
NULL
),
at a 2-point calibration either 100% or 0%(
NULL
).
The display will show
, and the referring reference which should be applied:
-
NULL
for 0% oxygen
-
0.2
for pure oxygen
As long as the display blinks, no valid reference is recognised by the instrument.
As soon the values for oxygen and temperature are stable, the calibration of the first point will be finished
.
The instrument tells you to apply the next reference (possible references are blinking in the display).
3. Second calibration reference: (Pt.2)
The display will show
, and the referring reference which should be applied:
-
A,R
for ambient air
-
0.2
for pure oxygen
-
NULL
for 0% oxygen
As long as the display blinks, no valid reference is recognised by the instrument.
As soon the values for oxygen and temperature are stable, the calibration of the second point will be
finished. At 2-point calibration the calibration will be finished and the electrode state resulting of the
successful calibration will be shown for a short time (evaluation in 10% steps: xx%
ELE[
).
At 3-point calibration the instrument tells you to apply the next reference (possible reference is blinking)
4. Third calibration reference: (Pt.3)
The display will show
, and the referring reference which should be applied:
As soon the values for oxygen and temperature are stable, the calibration of the second point will be
finished. At 2-point calibration the calibration will be finished and the sensor state resulting of the successful
calibration will be shown for a short time (evaluation in 10% steps: xx%
ELE[
).
In case of error messages being displayed during the calibration process, please refer to our notes
at the end of this manual! If a calibration cannot be carried out after an extended period of time, at
least one of the measuring values is unstable (oxygen partial pressure, temperature).
Please check your measuring arrangements!
7.3 Evaluation of Sensor State (
ELE[
)
Watch sensor state: press key "CAL" shortly once display show for a short time xx%
ELE[
.
It will show the electrode state resulting of the last successful calibration carried out.
The valuation is displayed in 10 percent steps: 100% means optimal sensor condition. Lower values are
indicating that the sensor life time will be reached soon.
Remark: But also an erroneous pressure may be the cause of low valuation values.
