Metrohm 1.873.0014, Manual

Page: 84 / 192

4.6 Determinations
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76 ￭￭￭￭￭￭￭￭
873 Biodiesel Rancimat
4.6.1 Preparing the instrument and the accessories
The cleanliness of instrument and accessories is an indispensable prerequisite
for
reliable, reproducible and correct analysis results . Even the slight-
est contamination could catalytically accelerate the oxidative decomposition
and lead to completely incorrect results. Therefore always observe the
instructions for use of measuring and reaction vessels in this section.
Check and prepare the instruments and vessels as follows (see also figure
5, page 14) :
1 Check openings for reaction vessels
￭
Check whether the openings are clean and empty. Blow the dust
out of the openings with nitrogen.
If the instrument is not used, always seal the openings with the
sealing plugs.
2 Fill the measuring vessels
Note
Only use measuring vessels and accessories which are absolutely
clean and in a perfect condition .
￭
Fill the cleaned measuring vessels with 60 mL distilled water
each.
For analysis times > 24 h approx. 7 mL more distilled water must be
added per day to compensate for the evaporation loss, so that the
electrodes remain safely immersed.
3 Insert the measuring vessels
￭
Place the clean measuring vessel covers equipped with a PTFE tube
on the measuring vessels.
￭
Insert the measuring vessels with the measuring vessel covers into
the openings provided for this on the 873 Biodiesel Rancimat and,
at the same time, carefully guide the connection plugs
(5-
15
) of the
cover carefully into the electrode connectors (3-
2
) .