Ohaus MB45 MOISTURE ANALYZER Manual - Manual (Page 53)

MB45 51
Ramp drying
Ramp drying is selected if substances are
not stable on exposure to the full heating
power of the halogen radiator at the start. In
ramp drying, sensitive samples are
prevented from decomposition by the gentle
heating. Ramp drying can also be used
successfully with substances which form a
skin.
Fast drying
The fast drying program is suitable for
samples with a moisture content between
5% and 15%. In fast drying, the radiator
power exceeds the set temperature value
during the first minute following the start of
drying. This compensates the endothermic
heat of vaporization and accelerates the
drying process. Note that the sample must
contain sufficient moisture during the first
minute to cool it.
Step drying
The step drying program has a use similar
to that of fast drying. The duration of the
excessive temperature stage and the
temperature value are freely selectable. It is
used primarily with samples with a
moisture content greater than 15%.
An alternate application possibility lies in the selective determination of the moisture at different
temperatures. Gypsum, for example, releases only its surface water at 50°C, whereas the water of
crystallization can not be separated until 168°C. With this drying program, it is thus possible to
determine the surface water and the water of crystallization separately within the same measurement by
a controlled temperature profile.