Metrohm 1.873.0014, Manual

Page: 169 / 192

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6 Troubleshooting
873 Biodiesel Rancimat
￭￭￭￭￭￭￭￭ 161
Problem Cause Remedy
The induction times are
not reproducible for
multiple determina-
tions. The reaction vessels used are
not clean.
￭
Free the reaction vessel of particles
(dust, cardboard, glass fragments etc.)
with compressed air before weighing
in the sample.
￭
Only use new, unused reaction ves-
sels.
The reaction vessels used are
scratched on the inside. Only use new, unused reaction vessels.
The reaction vessel cover
(5-
8
) is not mounted correctly
or is too loose.
￭
If the reaction vessel cover is oblique
or not completely mounted, press
down as far as the limit stop.
￭
If the reaction vessel cover is loose on
the reaction vessel despite correct
assembly, the cover has to be
replaced.
The connection to the measur-
ing vessel is not mounted cor-
rectly. Ensure that no air can escape through
leaks when transferring from the reaction
vessel to the measuring vessel.
The temperature in different
channels of a heating block
differs, as there are burn marks
at one or more places in the
opening of the heating block. Check temperature in the different posi-
tions
(see Chapter 4.8.4.1, page 141) . If
necessary, carefully remove the impurities
from the
cold heating block.
The temperature in different
heating blocks differs. Determine the temperature correction
Delta T for each block separately
(see
Chapter 4.4.2, page 50) .
The sample is not homoge-
nous. Homogenize sample.
The stability times are
not reproducible for
multiple determina-
tions. The cell constant was not
determined or does not corre-
spond to the value entered.
￭
Determine cell constant (see Chapter
4.4.1, page 48) .
￭
Ensure that the measuring cell is
always used in the same channel, so
that the cell constant determined
once also corresponds to the measur-
ing cell.
￭
Ensure that the measuring cell is not
contaminated. If necessary, clean
(see
Chapter 4.6.4, page 80) .