Thermo Fisher Scientific Alpha pH 2000 - Manual (Page 28)

6.2 Electrode Offset (OFS) sub-function
The electrode offset sub-function is only available if the controller is
configured for pH measuring. Use this sub-function to set an offset that
corrects the readings without removing the electrode from the control system.
The setting range is ±120 mV.
The controller will add or subtract the offset value from the measured pH and
display 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 system. Record the controller's pH reading at the
time you take the sample.
2. Measure the pH value of your sample using a calibrated pH tester, hand-
held meter, or bench meter. Record the correct pH value.
3. Select the “OFS” sub-function, then press the ENT key.
SETUP
HOLD
P H
SETUP
HOLD
P H
4. The display shows the current measured pH value (lower value) and the
current offset value (upper value). Press the
▲ or ▼ key to adjust the
pH value noted in Step 2. As the
▲ and ▼ keys
are being pressed to
adjust the pH value, the offset value also changes. Press the ENT key to
confirm the new offset value.
5. Continue with additional Setup procedures, or return to the Measurement
mode by pressing the
▲ and ▼ keys (escape) simultaneously.
Note: The offset value is reset during full calibration. See section 5 for
full calibration instructions.
Note: The offset sub-function is blanked out during ORP operation.