Stratos®Pro A4... PH User Manual

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 difference
is added to the measured potential.
mV ORP = mV meas – ΔmV
134
mV ORP
mV meas
= displayed ORP
= direct sensor potential
ΔmV = delta value, determined during
calibration
The sensor potential can also be related to another reference system
– e.g. the standard hydrogen electrode. In that case the temperaturecorrected
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.
Temperature dependence of commonly used reference systems
measured against SHE
Temperature
[°C]
0
10
20
25
30
40
50
60
70
80
Ag/AgCl/KCl
1 mol/l
[∆mV]
249
244
240
236
233
227
221
214
207
200
Ag/AgCl/KCl
3 mol/l
[∆mV]
224
217
211
207
203
196
188
180
172
163
Thalamid
[∆mV]
-559
-564
-569
-571
-574
-580
-585
-592
-598
-605
Mercury
sulfate
[∆mV]
672
664
655
651
647
639
631
623
613
603