IKA C 2000 control - Manual (Page 45)

IKA  -WERKE C 2000 basic / control Ver. 04 08.07
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The term “measurements” as used in the following presentation includes both
measurements for calibration of the calorimeter system (calibration measurements)
and actual measurements for determining gross calorific values. The difference con-
sists mainly in the evaluation (see Chapters 8 and 9 on this subject). The prepara-
tion and actual execution is nearly identical in both cases.
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Before precise measurements are possible with the calorimeter system, it must first
be calibrated. This is done by performing combustion on tables of FHUWLILHG EHQ]RLF
DFLG (see Accessories) with a known gross calorific value. From this process, the
heat energy that is required to raise the temperature of the calorimeter system by 1
degree Kelvin is used to determine the heat capacity (C value) of the system. This
value is used for the subsequent determinations of gross calorific value.
The heat capacity is determined with the measuring cell and the decomposition ves-
sel (DV). It has a substantial influence on the gross calorific value being determined,
and must be re-determined particularly when the device is first placed in service,
after maintenance service, and after parts are replaced.
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The calibration must take place under the same conditions that will prevail in the
subsequent experiments. If specific amounts of substances are added to the de-
composition vessel during combustion experiments (for example distilled water or
solutions), exactly the same amount of the substance must be added during calibra-
tion.
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• In order to achieve precise results, you should make certain that the tempera-
ture does not increase by more than 4 K during the combustion.
• The increase in temperature during the determination of gross calorific value
must be of the same magnitude as for the calibration (for example: 2 tablets =
about 1g benzoic acid ≅ 3.1 K). It may be necessary to perform several experi-
ments to determine the optimal sample size.
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A maximum of 4 decomposition vessels may be used when working with the calo-
rimeter system. This is possible by coding the decomposition vessels from 1 to 4.
For systems with automatic DV detection, the calorimeter recognizes which vessel a
measurement is being performed with and assigns its calibration parameters to it.
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