Ohaus MB45 MOISTURE ANALYZER Manual - Manual (Page 52)

50 MB45
8.3 Selection of the drying temperature (cont)
The following procedure is suggested for selecting the temperature.
— Estimate moisture content of the sample.
— Determine the decomposition temperature of the sample by experiments.
— Compare the measurement results with the reference method if one exists.
— If an excessive amount of moisture is evolved, lower the drying temperature. If the
experimental results are too low, the drying temperature was possibly too low or the drying
time too short.
With samples which have a high moisture
content, it is possible to shorten the
measurement time by selection of the step
or rapid drying program. Here, the greatest
part of the existing moisture is separated at
an elevated temperature.
The drying temperature is then lowered and
kept constant until the end of drying. The
excessive temperature is used for rapid
Measurement time
long
short
Drying temperature
vaporization of the moisture, but the effective sample temperature does not exceed the boiling
temperature of the liquid (cooling effect through endothermic vaporization). In certain cases, local
heating and decomposition could still occur at the sample surface.
8.4 Selection of the drying program
Various drying programs are available in the Halogen Moisture Analyzer. There are four programs which
control the temperature profile. They are:
—
Standard drying program
— Fast drying program
— Ramp drying program
— Step drying program
Standard drying
Standard drying is suitable for precise
determination of the moisture content of
most substances. For special cases or for
time optimized measurements, the selection
of a more complex drying program may be
advantageous.