6 | Operation and maintenance
G 1501
20 / 37
B-H86.0.12.DB2-2.1
6.3.1.3
Automatic pH calibration
The following steps describe how to calibrate the product automatically.
–
The product is switched on.
–
The pH electrode and, if applicable, a temperature sensor are inserted in the
product.
–
Ready-to-use GPH 7.0 buffer solution.
–
Ready-to-use GPH 4.0 or GPH 10.0 buffer solution.
NOTE
Automatic calibration can also be carried out with the pre-mixed PHL buffer solutions.
Since the temperature compensation relates to the GPH capsules, an error of a few
hundredths pH should be taken into account, depending on the temperature. Refer al-
so to the differences in the tables of the buffer solutions in
1.
Press the
Function key
for 4 seconds to open the
Calibration
menu.
(AL
appears in
the display.
2.
Release the
Function key
.
3.
PK 7
appears in the display.
4.
Place the electrode in the GPH 7.0 buffer solution.
5.
The product determines the correct value automatically. If the value is deter-
mined, the display flashes and an acoustic signal is issued to indicate a change to
the next calibration point.
6.
If the temperature sensor is not inserted, enter the temperature of the buffer solu-
tion by pressing the
Up key
and
Down key
and confirm the entry by pressing the
Function key
again.
7.
PK 4
and
PK 10
alternate in the display.
8.
Then, rinse the electrode with distilled or deionised water.
9.
Place the electrode in the second buffer solution. The product recognises whether
it is a
PK 4
or
PK 10
buffer solution automatically.
10.
If the temperature sensor is not inserted, enter the temperature of the buffer solu-
tion by pressing the
Up key
and
Down key
and confirm the entry by pressing the
Function key
again.
11.
Then, rinse the electrode again with distilled or deionised water.
After successful completion of the calibration the assessment of the electrode condi-
tion is displayed briefly in percent. Then, the current measurement is shown in the
display again. A low value can be the result of the age of the electrode, contaminated
or old buffer solutions or impurities on the BNC connector.
If the calibration is not completed successfully an error message is displayed.
(AL ERR.
. Confirm the error mes-
sage pressing the
Function key
. The product restarts and the standard value for the ze-
ro point and gradient are restored.
For this purpose, also refer to
Description
Prerequisite
Instruction
Outcome of an action
