In Process Calibration (Ph) - ABB AWT420 Operating Instruction

66 AW T4 2 0 | U N I V E R S A L 4 - W I R E , D U A L- I N P U T T R A N S M I T T E R | O I/A W T4 2 0 - E N R E V. B
...15 Calibration procedures
... pH/Redox/ORP calibration
...2-Point automatic calibration
6 Place the sensor into buffer 2 and press the
key to perform the high buffer calibration. The
calibration process screen is displayed:
Calibrate
pH 9.00 pH
Tmp 25.0 °C
Settling-Please Wait
Abort
On completion the result screen is displayed.
• If the calibration passes the slope and offset values
are displayed.
• If the calibration fails, the failure reason is displayed.
Note. The calibration can be canceled at any time during
the process by pressing the Abort
key.

In Process calibration (pH)

The In Process calibration is used when it is not possible to
remove the sensor from the process to perform the calibration.
In this calibration mode the actual sample is used to calibrate
the sensor.
In Process calibration is performed in two steps:
1 Sample collection
A grab sample is taken from the process and the sensor
records the measured value of the sample at that time.
Note. The grab sample should be taken as close to the
sensor as possible during the data collection period.
Performing this step erases any sample collections
performed previously for the selected sensor. Only the last
sample collection is stored in each sensor.
2 Collection complete
The pH of the sample is measured in the laboratory and
entered into the transmitter.
This sample must correspond to the last sample collection
step performed, or the calibration may not be correct.