Knick Stratos Pro A401B PH, User Manual

Page: 132 / 196

132
ORP (Redox) Calibration
The potential of a redox sensor is calibrated using a redox (ORP) buffer
solution. In the course of that, the difference between the measured
potential and the potential of the calibration solution is determined
according to the following equation. During measurement this differ-
ence is added to the measured potential.
= displayed ORP
= direct sensor potential
= delta value, determined during
calibration
mV
ORP
= mV
meas
– ΔmV mV
ORP
mV
meas
ΔmV
The sensor potential can also be related to another reference system
– e.g. the standard hydrogen electrode. In that case the temperature-
corrected potential (see table) of the reference electrode used must
be entered during calibration. During measurement, this value is then
added to the ORP measured.
Please make sure that measurement and calibration temperature are
the same since the temperature behavior of the reference electrode is
not automatically taken into account.
0
10
20
25
30
40
50
60
70
80
Temperature
[°C]
Ag/AgCl/KCl
1 mol/l
[∆mV]
Ag/AgCl/KCl
3 mol/l
[∆mV]
Thalamid
[∆mV]
Mercury
sulfate
[∆mV]
249
244
240
236
233
227
221
214
207
200
224
217
211
207
203
196
188
180
172
163
-559
-564
-569
-571
-574
-580
-585
-592
-598
-605
672
664
655
651
647
639
631
623
613
603
Temperature dependence of commonly used reference systems
measured against SHE