Swann AMU pH-Redox Operator's Manual page 51

AMU pH-Redox
Maintenance
Standard
pH Calibration
Process ORP
Calibration
Standard ORP
Calibration
Process
pH or ORP
Calibration
A-96.250.441 / 060619
The ideal pH electrode has an offset of 0 mV at pH 7 and a slope of
59.16 mV/pH unit. Real electrodes differ from this ideal. Therefore,
pH electrodes are calibrated with two buffer solutions, of different
pH values.
mV
177
118
59
0
-59
-118
-177
-236
-295
-354
-413
14 13 12 11 10
Same as process pH calibration.
Our reference electrode system is Ag/AgCl. The measuring value is
roughly 50 mV higher than the calomel reference system.
The slope of the ORP electrode is not defined. To compensate the
offset of gel electrodes, a calibration can be done with one buffer
solution. Because ORP electrodes are slow, it can take some time
after calibration until the measuring value is stable again.
The process calibration is based on a comparative measurement of
the on-line instrument with a correct manual measurement. Compare
the measuring value of the manual measurement with the on-line in-
strument and if necessary, enter the correct measuring value in the
menu <Maintenance>/<Process Cal.> of the on-line instrument.
NOTICE: For a reliable process calibration, the process value
has to be stable.
The deviation of the measuring values is shown as offset in mV. Se-
lect <Save> and press [Enter] to save the correct measuring value.
.
9 8 7 6 5 4
pH
3 2 1 0
49