Thermo Scientific ALPHA PH 560 Manual page 30

Electrode Offset
Settings
To Determine the
Offset Value:
Thermo Scientific Alpha pH 560
NOTE: 'Electrode Offset Setting' is not available when the pH
Controller is configured for ORP measurement mode.
(Refer Page 32 for switching measurement modes)
In applications where continuous pH measurement is required, it may
not be convenient to remove the electrode for calibration. In such cases,
an on-line offset adjustment is recommended. The pH Controller
allows you set an offset of up to ± 2.00pH to compensate for errors in
the pH electrode.
The pH Controller adds or subtracts the offset value from the measured
pH value and displays the corrected value. However, if you need to
offset the value beyond the average offset you would expect in your
application type, consider a full calibration or even electrode
replacement.
1. Take a sample from the liquid of pH measurement. Record the pH
reading of the pH Controller at the time the sample was taken.
2. Measure the pH value of your sample using another calibrated pH
meter having its own electrode (pH tester, hand-held meter or
bench meter)
3. The difference between these two readings is the offset
Figure 5–21. Electrode Offset Settings
From pH measurement mode press ENT key to enter setup
1 1
mode as described in page 24. The LCD shows the first
screen of setup mode (OFS). Press ENT key to access
electrode offset setting (OFS).
The upper display shows the last configured offset value (if
2
any), otherwise zero. The lower display shows currently
measured pH reading (including last configured offset value).
Allow the reading to stabilize. LCD shows 'READY'
annunciator when the reading is stable.
Press ▲ or ▼ key to set the upper display to the newly
calculated offset value.
As the upper display value (offset) changes, the pH
3
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