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inoLab 740
Why calibrate?
When to calibrate?
AutoCal
ConCal
AutoRead
Calibration record
ba75446e05
07/2010
6.2
Calibrating pH measurements
pH electrodes age. This changes the asymmetry and slope of the pH
electrode. This may cause the measuring system to ignore the limits of
a calibrated system. Calibration determines the current values of the
asymmetry and slope and stores them in the measuring module.
Calibration must be performed at regular intervals.
After connecting another electrode
When the sensor symbol flashes:
– after expiry of the calibration interval
– after a voltage interruption, e.g. battery change
You can choose between two calibration procedures: AutoCal and
ConCal:
is a fully automatic calibration using the datasets selected for buffer
solutions in the pH buffer menu.
The buffer solutions are automatically recognized by the measuring
instrument. Depending on the instrument setting (see page 74), the
instrument displays the relevant buffer nominal value or the current
electrode voltage in mV. The calibration can be terminated after the first
buffer solution. This corresponds to a single-point calibration.
is the conventional two-point calibration method using two buffer
solutions (pH 7.0 ± 0.5 and any other buffer solution) or a single-point
calibration using any buffer solution that is used as a high-speed
method.
When calibrating with AutoCal, the AutoRead function is automatically
activated.
The current AutoRead measurement can be terminated at any time
(accepting the current value) by pressing
The calibration record contains the calibration data of the current
calibration. You can call up the calibration record by outputting the data
storage (section 11.3).
Note
You can automatically print a calibration record following calibration. To
do so, switch on the printer before calibrating (print LED lights up
green). After a valid calibration, the record is printed.
g
.
pH
71
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