6 preparing and performing measurements – IKA C 200 User Manual

Page 19

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The system must be calibrated in every work

mode used.

If a calorimeter is operated with several de-

composition vessels, you will need to deter-

mine the heat capacity of the system for each

decomposition vessel.

Ensure that calibration is carried out under the
same conditions as the subsequent tests. If sub-
stances are used in the decomposition vessel in
combustion tests (e.g. distilled water or solu-
tions), you must use exactly the same amount of
this substance for calibration.

For more detailed information on calibration, ple-
ase see the relevant standards.

6.1 Decomposition vessel C 5010

If several decomposition vessels are used,

their individual parts must not be interchan-

ged (see Stamping individual parts).

To prolong the life of wearing parts (o-rings,

seals, etc.) we recommend that you always

work with a water trap.

5.4 Calibration

The calorimeter system must be calibrated before
accurate measurements are possible. This is done
by combusting tablets made of certifi ed benzoic
acid (see Accessories) with a known calorifi c va-
lue. The heat quantity required to raise the tem-
perature of the calorimeter system by one Kelvin
is used to determine the heat capacity of the so-
called "C-value" of the system. For this calculati-
on the formula (1) (see section 5.1) is adapted:

C = (Ho * m + QExt1 + QExt2) / DT (2)

This value is used for determining the following
calorifi c values.
The heat capacity is determined by the measu-
ring cell and the decomposition vessel. It has a
signifi cant infl uence on the calorifi c value to be
calculated and must be redetermined in particular
when using for the fi rst time, after servicing and
when parts are replaced. A monthly control mea-
surement is recommended.

The term "measurements" below refers to both
the measurements to calibrate the calorimeter
system (calibration measurements) and the actual
measurements for determining the calorifi c value.
The difference lies in the calculation (cf. section
5, formulae (1) and (2)), whereas preparation and
performance are virtually identical.
Exact measurements are only possible when the
individual test steps are carried out carefully.

You must therefore follow the exact proce-

dure described in section 1 "For your safe-

ty” and in the following sections

Please also see section 5 "Calorimetric measure-

Failure to observe these instructions could re-

sult in damage to the decomposition vessel.

Damaged decomposition vessels could crack!

Follow the operating instructions for the de-

composition vessel!

6 Preparing and performing measurements

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