Orp Calibration - Honeywell APT4000PH User Manual

ORP calibration

ORP calibration mode is automatically preset when ORP meas-
urement is configured. The potential of a redox electrode can
be calibrated using a redox buffer solution. For this purpose,
the difference between the potential measured and the poten-
tial specified for the calibration solution is determined. During
measurement, the APT4000PH then adds this difference to the
potential measured.
mV ORP = mV meas + ∆mV mV
ORP
mV
meas
∆mV
It is also possible to relate the elctrode potential to another ref-
erence system – such as the standard hydrogen electrode. In
that case, the temperature-corrected potential (see table) of
the reference electrode used must be entered. During measure-
ment, this value is then added to the ORP measured.
Please make sure that measurement and calibration tempera-
ture are the same, since the temperature response of the refer-
ence electrode is not automatically taken into account.
Temperature dependence of commonly used reference systems
Temperature Ag/AgCl/KCl
[°C] 1 mol/l
[∆mV]
0 249
244
10
20 240
25 236
30 233
227
40
221
50
60 214
70 207
80 200
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=
displayed ORP
=
direct electrode potential
=
delta value, calculated during
calibration
Ag/AgCl/KCl Thalamid Mercury
3 mol/l [∆mV] sulfate
[∆mV] [∆mV]
224 -559 672
217 -564 664
211 -569 655
207 -571 651
203 -574 647
196 -580 639
188 -585 631
180 -592 623
172 -598 613
163 -605 603
APT4000PH
Display Action
Activate calibration
(Press CAL).
Enter mode code 1100
Select with key, edit number
with key, proceed with ENTER.
Remove the electrode and temper-
ature probe, clean them and
immerse them in the redox buffer.
Enter desired value for redox buffer
(Secondary display: Electrode
potential displayed for approx. 6 s)
Select with key,
edit number with
proceed with ENTER
Display of electrode data
(delta value)
Proceed with ENTER.
Rinse electrode and temperature
probe and reinstall them.
The measured ORP value [mV] is
shown in the main display alter-
nately with "Hold",
"enter" flashes.
End with ENTER.
Remark
If an invalid code is
entered, the
APT4000PH returns
to measuring mode.
Display
(approx. 3 sec)
APT4000PH is in the
Hold mode.
After approx. 6 s the
secondary display
shows the measured
temperature.
key,
"Zero" and "enter"
icons are flashing,
Sensoface is active.
After end of calibra-
tion, the outputs
remain in Hold mode
for approx. 20 sec.
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