Instruments for an ideal cooking process

The Berthold measuring system LB 568 provides an online and real-time moisture measurement of digester-fed wood chips. The LB 568 generates multiple microwaves in a wide frequency range, emitted by an antenna below the conveyor. The microwaves penetrate the wood chips and are received by a second antenna above the belt. When penetrating the wood chips, the microwave signal‘s characteristics change in terms of attenuation and phase shift. These changes directly correlate to the wood chip moisture. Fluctuations in the layer height and bulk density can be compensated for by using a radiometric area weight measurement. The complete system thus provides a stable and reliable moisture reading. The microwave moisture meters are installed on the feeder belt to the digester. The electronics for data evaluation are installed close to the antennas. Depending on the representativeness of the sampling and the measuring conditions, a typical accuracy of better than +/- 1.0 % moisture can be achieved.

Customer benefits

  • Accurate moisture leads to accurate solids addition leads to accurate digester chemical charge
  • Measurement independent of wood species
  • Operates reliably at moisture levels up to and above 50%
  • Transmission measurement provides representative sample as opposed to traditional „surface only“measurements


  • Installs around existing conveyor belts
  • Non-contact measurement
  • FCC compliant
  • State-of-the-art microwave transmission technology measuring the material cross-section
  • High measurement repeatability


3 Results

Berthold's Measurement Solutions

MicroPolar LB 567/568

Microwave moisture analysers for all kinds of bulk materials, non-contacting, reliable and maintenance free

LB 571 Microwave Resonator

Sensor for online moisture measurement of bulk materials