IKA C 2000 control - Manual (Page 22)

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IKA  -WERKE C 2000 basic / control Ver. 04 08.07
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For information on the fundamental principles of calculation for gross calorific value
and heat value, please refer to the applicable standards (for example: DIN 51 900;
ASTM D 240; ASTM D 1989).
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As determined by the system, during a combustion experiment, not only is heat
generated from the combustion of the sample, but heat also occurs in the form of
extraneous energy.
This may fluctuate considerably in proportion to the heat energy of the fuel sample.
The combustion heat of the cotton threat that ignites the sample and the electrical
ignition energy would result in distorted values of the measurement. This effect is
taken into consideration in the calculation with a correction value.
Substances with low flammability or substances that burn poorly undergo combus-
tion in combination with combustion aids. The combustion aid is first weighed and
then added to the crucible with the sample. From the weight of the combustion aid
and its known specific gross calorific value, it is then possible to determine the
quantity of heat that is introduced thereby. The result of the experiment must be
corrected by this amount of heat.
The C 14 disposable crucible is a combustible crucible that can be used instead of a
traditional crucible. The disposable crucible undergoes total combustion with no
residue. If a disposable crucible is used, there is then no need for a cotton thread.
The crucible is in direct contact and is ignited by the fixed ignition wire of the de-
composition vessel.
The purity of the material used in the disposable crucible prevents any chemical
contamination of the sample material from occurring (no blind values).
Decomposition vessels in which the disposable crucible is used must be retrofitted
with an additional part (holding surface C 5010.4, see accessories). The sample is
weighed into the disposable crucible as usual. In most cases, no additional combus-
tion aid is necessary because the disposable crucible itself acts as the combustion
aid.
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