Xylem Multi 3420 - Manual (Page 74)

Operation Multi 3420
74 ba75864e11 02/2011
4.9.5 D.O. calibration
Why calibrate? D.O. sensors age. This changes the slope of the D.O. sensor. Calibra-
tion determines the current slope of the sensor and stores this value in
the instrument.
Note
The FDO
®
925 D.O. sensor ages so little it does not have to be regu-
larly calibrated.
To detect changes of the sensor as early as possible, the FDO
®
Check
procedure can be useful (see section 4.9.4).
When to calibrate?
z If your evaluation of the FDO ®
Check procedure suggests a calibra-
tion
z When the calibration interval has expired
z If your accuracy requirements are especially high
z Routinely within the scope of company quality assurance measures.
Calibration procedures Calibration in water vapor-saturated air.
To calibrate the FDO
®
925 sensor, use the check and storage vessel,
FDO
®
Check.
Stability control
(AutoRead)
In calibration, the Stability control function (AutoRead) is automatically
activated.
Display calibration data
and output to interface
You can have the data of the last calibration displayed (see section
4.10.6). Subsequently, you can transmit the displayed calibration data
to the interface, e. g. to a PC, with the key.
Note
The calibration record is automatically transmitted to the interface after
calibrating.
Sample record
Calibration evaluation After the calibration, the meter automatically evaluates the current sta-
tus of the calibration. The evaluation appears on the display and in the
calibration record.
Multi 3420
Ser. no. 10139695
CALIBRATION Ox
Calibration date
30.03.2010 16:13:33
FDO 925
Ser. no. 10146858
SC-FDO 925 10158765
Relative slope 0.98
Sensor +++