RADWAG MA 200.3Y Moisture Analyzer - Manual (Page 67)

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uniformity and other. The sampling process should be carried out as quickly as
possible, so that a sample does not loose or absorb humidity from surrounding
area.
Applied sampling standards should match individual user needs and
requirements of tested material, its consistence and sample size.
Number of samples
Increasing number of tested samples also increases statistic measurement
certainty. Number of samples depends on uniformity of tested material, its
purity, accuracy of applied measuring method and anticipated accuracy of
obtained results.
Material mechanical disintegrating for measurements
Applied disintegrating method should be selected appropriately to tested
material. Substances that are hard and brittle (crisp) can be disintegrated by
cutting. Grinding such substances may cause their heating and thus humidity
vaporization, resulting in unreliable measurement results. Unless a substance
can be prepared for measurement otherwise than grinding, any possible
moisture content loss should be calculated.
Use of high-silica sand
Ensuring optimum substance drying requires that a sample has the largest
possible surface for moisture content vaporization. Test results of moisture
content in substance which surface has a form of a shell (e.g. glucose syrup) or
doughy (e.g. butter), can be much more reliable if a sample is mixed with a
dried high-silica sand (improvement of measurement accuracy and
repeatability).
Grease in a form of paste or melting substances
Such substance requires testing with use of a filter made of glass fibre, which
considerably increases active evaporation surface by separating the substance
between the fibre. Initial filter drying is necessary only in case of measurements
which require very high accuracy.
Liquid substances
It refers to liquid substances, which by creation of drops on their surface,
caused by surface tension, may render difficulties in drying process. In such
cases, it is proved to use a glass fibre filter to shorten measurement time. The
filter causes separating tested liquid around the fibres, and increasing active
evaporating surface. Initial filter drying is necessary only in case of
measurements which require very high accuracy.
Substances with structure of leather or temperature sensitive
In case of such substances it is proved to a glass fibre filter. While testing, a
substance is placed on a drying pan, and sample surface is covered with a filter,
which protects the sample from direct heat radiation. In such case, the sample is
heated by convection (which is milder than radiation).
Substances containing sugar