78 DBS-BA-e-1311
12.7 Drying temperature
Bear in mind the following factors when setting the drying temperature:
Surface of the sample:
Compared with powdery or grainy samples, liquid and spreadable samples have a
smaller surface for the transmission of heat energy.
The use of a glass fibre filter improves the heat application.
Colour of sample:
Light-coloured samples reflect more heat radiation than dark ones and therefore
require a higher drying temperature.
Availability of volatile substances:
The better and faster the water or other volatile substances can be disposed, the
lower a drying temperature is required. If water is difficult to get to (e. g. in
synthetics), it has to be calcined at high temperatures (the higher the temperature,
the higher the water vapour pressure).
Results equivalent to other moisture analysing methods (e. g. drying chamber) can
be achieved by experimentally optimising the setting parameters such as
temperature, heating level and shutoff criteria.
12.8 Recommendations / Guidelines
Prepare standard sample:
- Crush sample, as required, and spread it evenly in the aluminium dish.
Prepare special samples:
- For sensitive or hard to spread test materials (e. g. mercury) a glass fibre filter
is available for use.
- Apply the sample equally on the glass fibre filter and cover it with a second
glass fibre filter.
- The glass fibre filter is also useful as a protection when splashing materials
are dealt with (each splash falsifies the final result).
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