KROHNE OPTISENS PAC 050 EN - Manual (Page 16)

Manual OPTISENS PAC 050
OPTISENS PAC 050 16
4.4 Calibration
Main menu Calibrate
Calibrate  Meas. val. 6.99pH
. Cal. press & 
. Slope
. 058 mV/pH
The calibration solutions stored as „buffers
used“ are recognised automatically. It does
not matter whether you start with buffer 1
or 2.
Sensor zero
001 mV
Basic settings
Basic settings  . Buffers used
Buffers used  Buffer 1
7.00 pH
Buffer 2
4.00 pH
Sensor buffer
7.00 pH
4.4.1 Calibration procedure
1) Switch the controller OFF and select manual temperature compensation. Enter the temperature of the
calibration solutions.
2) Immerse the electrode in one of the calibration solutions. Wait until the measured value is stable, then
calibrate by pressing keys and - while still applying pressure - additionally key .
The pH of the calibration solution is now displayed as measured value.
3) Rinse the electrode and repeat step 2 with the second calibration solution.
4) Check the slope and sensor zero-point, then put the electrode back into the armature. Select automatic
temperature compensation and switch ON the controller.
NOTE The slope should be close to 59 mV/pH, the zero-point close to 0 mV. The slope decreases and the zero
error increases with time. When either value exceeds certain limits, the instrument displays an error message
indicating that the electrode has to be replaced.
4.4.2 Buffers
At works the following buffers are stored:
• Calibration solutions: buffer solutions pH 4 and pH 7
• Inner buffer of the electrode: pH 7
If you want to use other calibration solutions, adjust the values - it does not matter if you start with the higher
or the lower pH.
If you are using electrodes with a special inner buffer, adjust the pH value of the sensor buffer, since this
value is used as zero for the calculation of the measured values. You will find the pH of the sensor buffer
printed on the electrode.