Thermo Fisher Scientific Alpha pH 2000D - Manual (Page 22)

6.2 Electrode Offset (OFS) sub-function
The electrode offset sub-function is only available if the transmitter 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 transmitter will add or subtract the offset value from the measuring 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, and then press the ENT key.
SETUP
HOLD
P H
SETUP
HOLD
P H
4. The display shows the current measured pH value (lower section of the display) and the current offset
value (upper section of the display). 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.
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