H74.0.05.6C-06
Operating Manual GMH 3651
page 12 of 18
8.2 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.
The calibration can be performed in gases (
[AL A,R
: Air, 100% Oxygen and/ or 0% oxygen like nitrogen) or in
saturated water solutions (
[AL AQUA
). The water solutions therefore have to be
“gased” sufficiently with the
referring gases. Another alternative for 0% is a Sodium sulfite solution ( can also be used at
[AL A,R
)
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 or oxygen saturated water
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 or
AQUA
for air saturated water
-
0.2
for pure oxygen or oxygen saturated water
-
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!
8.3 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 a erroneous pressure may be the cause of low valuation values.
