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Dissolved oxygen
50
6.
Wait for the end of the measurement with stability control (beep,
[HOLD][AR] status indicator) or take over the calibrated value with
<ENTER>
.
The measured value is frozen.
7.
Switch to the measured value display with
The check measurement is not documented.
7.2.4 Evaluation
The evaluation is based on the accuracy required and defined by the user (e.g.
± 2 %). Together with the nominal value (100 %) this results in a validity scope
for the check of 98 to 102 % (see example).
If the measured value is within the validity scope, no cleaning or user
calibration is required.
If the measured value is outside the validity scope, the sensor shaft and
membrane should be cleaned, and the check should then be repeated
(see section 5.4.1).
Example:
– Required accuracy: ± 2 %.
– In water vapor-saturated air or air-saturated water, the nominal
value for the relative D.O. saturation (abbreviated: saturation) is
100 %.
– Therefore, the validity scope is 98 ... 102 %
– The check resulted in a measured value of 99.3 %
The measurement error is within the specified validity scope.
No cleaning or user calibration is required.
7.3
Calibration
7.3.1 Why calibrate?
D.O. sensors age. This changes the slope of the D.O. sensor. Calibration deter-
mines the current slope of the sensor and stores this value in the instrument.
®
The FDO
ularly calibrated.
To detect changes of the sensor as early as possible, the
®
FDO
Check procedure can be useful (see section 7.2
®
FDO
C
HECK
7.3.2 When to calibrate?
If your evaluation of the FDO
When the calibration interval has expired
925 D.O. sensor ages so little it does not have to be reg-
(
FDO
CHECKING THE
®
Check suggests calibrating
®
inoLab
Multi 9310 IDS
<M>
.
®
925), page 48).
ba75937e10
08/2021
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