RADWAG MAX 60 Moisture Analyzer - Manual (Page 76)

- 76 -
13.6. Drying mode analysis
In the first case the drying mode is an asymptote. The humidity content in a
sample reaches a constant and it does not change after long drying time.
Using this drying mode enables easy obtaining of repeatable humidity content
in a tested sample.
The measurement result refers specifically to the constant asymptote value. It
easily corresponds and it is simple to determine appropriate finish mode
criterion.
The other type of drying mode in its initial stage is carried out rapidly, and later
on it slows down. Humidity content never reaches a constant value. The drying
mode in this case may form in the following way:
The sample demonstrates thermal decomposition. The decomposing is sample
(product) evaporation, and the sample losses weight. The fat, oil, plastics and
other volatile ingredients may cause slower evaporation process than in case
of water. The ingredients that evaporate hard cause decreasing of sample
mass.
The measurement result using this drying mode can be optimistic:
•
Decreasing temperature may slow down ingredients’ reaction.
•
Selecting an appropriate finish mode criterion may enable detecting an
end of the analysis in the described drying point.
•
Selecting a constant drying process often ensures very good results.
•
Permanent maintaining initial mass of a sample to be tested
(+10%....+20%).