Dissolved oxygen (D.O.)
Multi 9420
72
ba75964e04
04/2015
Stability control
(AutoRead)
In the FDO
®
Check procedure, the Stability control function (AutoRead) is
automatically activated.
Proceed as follows to carry out the FDO
®
Check procedure:
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 %
1.
Connect the D.O. sensor to the meter.
2.
Place the D.O. sensor in the check and storage beaker, FDO
®
Check.
The sponge in the check and storage beaker must be moist (not
wet). Leave the sensor in the check and storage beaker long
enough so it can adapt to the ambient temperature.
3.
Start the FDO
®
Check procedure in the measuring menu with
FDO
Check / Start FDO Check
.
The meter switches to the measured parameter, %.
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 indi-
cator 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.