KERN & SOHN MLB 50-3C - Manual (Page 58)

58 MLB_C-BA-e-1431
16.4 Preparing a sample
Prepare one sample at a time for measuring. This prevents the sample from
exchanging moisture with its surroundings. If several samples have to be taken at the
same time, they should be packed in airtight boxes so that they do not undergo
changes during storage.
To receive reproducible results, spread the sample thinly and evenly on a sample
dish.
Patchy spreads will produce inhomogeneous heat distribution in the sample to be
dried resulting in incomplete drying and increased measuring time. Sample clusters
generate increased heating of the upper layers resulting in combustion or
incrustation. The high layer thickness or possibly arising incrustation makes it
impossible for the moisture to escape from the sample. Due to this residual moisture,
measured results calculated in this way will not be comprehensible or reproducible.
Preparing a sample from bulk material:
No special sample preparations are necessary for
bulk materials.
Spread powdery or grainy samples evenly on the
sample dish.
Coarse sample may need crushing (grind, crush
using a mortar).
Preparing a sample from liquids:
This, too, does not require any special sample
preparation.
Spread glutinous or sticky samples thinly. It is
advisable to use glass fibre filters.
Weight loss caused by splashes can be prevented by
covering the sample with a glass fibre filter. If using
glass fibre filters, their weight has to be deducted
from the gross weight.
Preparing a sample from solids:
In this case special preparation of the sample is
advisable, as drying, in particular the drying time,
depends on the surface as well as the thickness of
the sample.
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