TopCal S CPC 300
6 Commissioning
Hauser
45
6.5.6
Set up 1 – Temperature
The pH value requires temperature compensation for two reasons:
1.
Temperature effect of the electrode:
The electrode slope is dependent on the temperature. Therefore this effect must be
compensated for temperature changes
(
temperature compensation
, see below).
2.
Temperature effect of the medium:
The medium pH value is also temperature dependent. For high-accuracy measure-
ments, the pH value related to temperature
can be entered in table form (
medium temperature compensation
, see below).
Temperature compensation
ATC: Automatic temperature compensation: The medium temperature is measured with
a temperature sensor. This temperature is used via the temperature input in the
Mycom S CPM 153 to adjust the electrode slope to the medium temperature.
MTC: Manual temperature compensation: This is advisable in processes which run at a
constant temperature. Here, you enter the temperature value manually, which is used to
adjust the slope of the electrode to the medium temperature.
MTC+Temp.: The pH value is corrected with the manually entered temperature (see
MTC). On the display however, the value which appears is what the temperature sensor
measures in the medium.
Medium temperature compensation
Tables for Medium 1...3:
For medium temperature compensation, tables can be created in the CPM 153 for three
different media. Before starting the process, the most suitable table for the active
medium can be selected.
Procedure:
•
Take a sample from the process. The pH value should be as near as possible to the
reference value of the process.
•
In the laboratory, heat the sample to
at least
the process temperature.
•
During cooling, record the value pairs for pH and temperature at those temperatures
at which you later wish to take measurements (e.g. process temperature and ambient
temperature in the laboratory).
•
Enter these recorded value pairs in the table (Field GBB3). As a reference tempera-
ture (Field GBC1) select the temperature, at which the reference value of the process
is defined (e.g. ambient temperature in the laboratory).
Содержание TopCal S CPC 300
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