Microwaves penetrate the bulk material, causing a rotation of the free water molecules. As a result the velocity of the microwaves is slowed down (phase shift) and their intensity is weakened (attenuation). Both effects are measured and used as a direct indication of the moisture content.

These measuring effects are already achieved by using very small microwave transmission power – typically 0.1 mW. Consequently the measured material is neither warmed nor modified. Factors such as color, viscosity, inhomogeneous composition or dust have no or only a negligible effect on the measurement performance.


Fast neutrons are slowed down by scattering the hydrogen nuclei. But they are hardly affected by scattering other material components.

The measurement system comprises a source, emitting a cloud of fast neutrons. After their interaction with the water molecules within the measured material, the attenuated neutrons are measured with a specific detector that is sensitive to slow neutrons only. As the number of slow neutrons corresponds to the hydrogen content, the neutron technology is a extremely reliable measure for the product moisture.

It is not affected by temperature, pressure, conductivity or varying particle sizes and even frozen water can be measured reliably.

Online moisture measurement on bulk materials

The MicroPolar measures the moisture content of a wide variety of bulk solids online. The measurement takes place on the conveyor belt, bunker, silo or at the shaft. The microwave transmission technology used allows non-contact measurement of the entire material cross-section. The result is accurate and representative online measurements for quality assurance and process optimization.

Typical areas of application for all kind of bulk materials are found in mining, power plants, coking plants, chemistry, building materials, wood and paper industry.

Further information about our microwave moisture measurement

Moisture measurement in storage and weighing containers

The radiometric measuring technology measures the material moisture in storage and weighing containers. Large material volume (up to 1 m diameter) which is detected by the measurement offers you extremely representative measurement results. The moisture is measured either from the outside through the container wall or with an inserted dip tube.

The measurement setup is extremely robust and has already proven itself, in numerous difficult applications such as moisture measurement of coke, sinter, sand, gravel, calcareous sandstone as particularly accurate and reliable. Once installed and calibrated, no further recalibration or maintenance is required.

Further information about our radiometric moisture measurement


Advantages at a glance

  • No contact with the material to be measured
  • Precise and maintenance-free operation
  • Measurement of the whole material profile
  • Easy to install on existing conveyors or chutes
  • State of the art technology

  • Subsequent installation on existing systems possible
  • High availability and therefore high operational safety
  • Reliable measurement without recalibration