51
18 Conductivity indicator
18.6 Calibration
The cell constants of conductivity cells vary somewhat from one example to
another, and also drift with use (because of deposits and wear). This results in
a change of the output signal from the cell. It is therefore necessary that the
user is able to compensate for the deviations of the cell constant from the
nominal value, either by manual input or an automatic calibration of the relative
cell constant K
rel
,
Chapter 18.7 “Calibrating the relative cell constant”, page 53
.
The time interval between two calibrations depends on the conditions in which
the cell is used.
The conductivity of a solution varies with the temperature, so for correct
measurement both the temperature and the temperature coefficient of the
solution being measured must be known. The temperature can either be
measured automatically, with a Pt100 or Pt1000 temperature probe, or set
manually by the user. The temperature coefficient can be determined
automatically by the JUMO dTRANS Az 01, or entered manually.
.
Preparation for
calibration
Before the first calibration, it is necessary to select the method of temperature
acquisition (automatic or manual) to be used during calibration.
.
Select type of
temperature
acquisition
The instrument is in the measurement mode.
✱
Unlock the configuration level, if necessary,
“Unlocking the levels”, page 27, (code word 0300).
✱
Press the
key twice, for more than 2 seconds, to access the
configuration level.
The lower display shows “C111”.
Use the
and
keys to set the configuration parameter:
✱
Press the
key (confirmation)
✱
Press the
key (return to the measurement mode).
Cancel
You can change back to the measurement mode at any time, by
pressing the
key.
EXIT
If subsequent calibrations are carried out with the same settings,
then it will not be necessary to set the temperature acquisition
again.
Type of temperature acquisition
X
X
X
0
Manual temperature compensation
0
Automatic temperature compensation with Pt100
1
Automatic temperature compensation with Pt1000
2
PGM
PGM
EXIT
