Multi 9310 Dissolved oxygen
ba75937e03 12/2011 51
7.2.4 Evaluation
The evaluation is based on the accuracy required by the used. Together with
the nominal value (100 %) this results in a validity scope for the check.
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.
4. Start the measurement with <ENTER>.
The measured value is checked for stability (stability control).
The [AR] status indicator is displayed. The measured parameter flashes.
5. Wait for the end of the AutoRead measurement ([HOLD][AR]) status
indicator or
take over the measured value with <ENTER>.
The measured value is frozen.
6. Switch to the measured value display with <M>.
The check measurement is not documented.
01.07.2011
08:00
[t90= 30 s]
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