6\vwhp fdoleudwlrq – IKA C 5000 control Package 2/12 User Manual
Page 59

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Before it is possible to make precise measurements with the calorimeter system, it
must be calibrated. This is done by burning tablets of
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(see
accessories) with a known gross calorific value. This makes it possible to determine
the heat capacity (the C value) of the system based on the amount of heat that is
required to raise the temperature of the calorimeter system by 1 degree Kelvin. This
value is then used for subsequent determinations of gross calorific values.
The heat capacity is determined by the measurement cell and the decomposition
vessel. It has a substantial influence on the gross calorific value being determined,
and must especially be determined when the system is first placed in service, after
maintenance or repair work, and when parts are replaced.
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Calibration must take place under the same conditions as will be found during sub-
sequent experiments. If measured quantities of substances (for example distilled
water or solutions) will be used in the decomposition vessel, exactly the same quan-
tity of these substances should be used during calibration.
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•
In order to achieve precise results, you should take care that the combustion not
exceed an increase in temperature of 4 K. This applies as a rule of thumb if no
benzoic acid is being used during the calibration.
•
It should be mentioned here in advance that when determining gross calorific
values, the increase in temperature must be roughly the same as for the cali-
bration (for example 2 tablets – approximately 1 g of benzoic acid
≈
2.6 K)
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When working with the calorimeter system, a maximum of 4 decomposition vessels
can be used. The maximum for the duo-control system is 2 decomposition vessels
per measurement cell. This is possible by coding the decomposition vessels from 1
to 4. The system recognizes which decomposition vessel an experiment is being
performed with and assigns its calibration parameters to it.
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To do this, attach the black coding rings into the recesses on the decomposition
vessel provided for this purpose.
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