Basic Principles
Purpose
The moisture analyzer can be used for quick and reliable determination of the
moisture content of materials of liquid, pasty, and solid substances using the
thermogravimetric method.
Material
The moisture of a material is often mistakenly equated to its water content. In fact,
the moisture of a material includes all of the volatile components which are emitted
when the sample is heated, irrespective of the type of material. Among such volatile
substances are:
– Water
– Fats
– Oils
– Alcohols
– Organic solvents
– Flavorings
– Volatile components, products of decomposition (when a sample is overheated)
There are many methods for determining the moisture content of a substance.
Basically, these methods can be divided into two categories:
When absolute methods are used, the moisture content is directly determined
(for example, as a weight loss registered during the drying routine). These methods
include oven drying, infrared drying, and microwave drying. All three of these
methods are thermogravimetric.
When deductive methods are used, the moisture content is indirectly determined.
A physical property related to the moisture in the substance is measured (e.g.,
conductivity). These methods include capacitive and spectroscopic approaches.
Thermogravimetry is the process of determining the loss of mass that occurs when
a substance is heated. In this process, the sample is weighed before and after being
heated, and the difference between the two weights is calculated.
In a conventional drying oven, circulating hot air warms the sample from the
outside to the inside. Efficiency is lost during drying because as the moisture
evaporates, it cools the sample surface.
By contrast, infrared rays (IR rays) penetrate the substance. The majority of the rays
reach the interior of a sample, and then directly heat the sample.
IR-Strahlung
Substanz
Wärmeenergie
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Operating Instructions Moisture Analyzer MA160
Basic Principles
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