Berthold Industrial Systems

Moisture measurement with the Micro-Moist LB356
on a conveyor in a chute in a pipe

Measuring moisture using microwaves Moisture content is an important parameter in many production processes. The measurement of moisture is therefore a basic prerequisite for process optimization, quality assurance, and the saving of energy and raw materials. With the Micro-Moist microwave moisture gauge you have a measuring system that determines the moisture of the widest range of materials on-line, is contactless, reliable and maintenance-free - even under harsh operating conditions - and remains stable over a long period with a high level of accuracy.

Measuring principle The Micro-Moist LB 356 system for moisture determination is based on microwave technology. Microwaves are influenced in their intensity and speed of propagation by free water molecules. The reduction in intensity (attenuation) and velocity (phase shift) of the microwaves are directly related to the moisture content in a product. Micro-Moist measures on several frequencies. In each measuring cycle at each discrete frequency, both attenuation and phase shift are determined and tested for plausibility. Only accepted measurement values are used in calculating the moisture content. Basically, only non-conducting material can be measured. Decisions regarding steel-reinforced conveyor belts are made on a case-by-case basis.

The advantages of microwave technology

• high and selective sensitivity to free water molecules
• the entire cross-section of the material is measured, in this way a representative measurement is possible even where the distribution of moisture is not uniform

Advantages compared with other microwave-based measuring systems for determining moisture

• Non-contact transmission method The entire cross-section of material is measured, without any contact with the product
• Measuring phase shift and/or attenuation Fluctuations in particle size, product temperature and composition are disturbing parameters for only attenuation measurement. In phase measurement or combined phase and attenuation measurement, these disturbing influences are reduced
• Measuring many discrete frequencies With single frequency measuring systems, spurious reflections and resonance often occur. Micro-Moist, with its multifrequency measuring system, identifies and eliminates inaccurate measurements caused by reflections and resonance (plausibility check).

Using the LB356 for the measurement of moisture on a conveyor belt

The Micro-Moist LB356 measures on-line the moisture contained in the most diverse bulk materials on conveyor belts. This is particularly advantageous in that the measuring method is completely contactless. Originally developed to measure moisture in hard coal, Micro-Moist has proved itself in a wide variety of application domains over recent years. Measuring the moisture in foodstuffs, wood chips, animal food, sand and soil are just a few examples of domains where it is used successfully.

Components: Transmitting and receiving antennae High frequency antenna cable LB 356 evaluation unit Area weight measuring device comprising scintillation counter and shielded radiation source

Using the LB356 for the measurement of moisture in a chute

The ability to measure moisture in a chute is particularly advantageous. This arrangement provides a fixed volume of material which in turn has a positive influence on the performance. Thus, under certain circumstances, the radiometric area weight measurement may be not required. In order to facilitate this measuring arrangement, Berthold can supply a chute made of plastic. This chute is ideal for measuring all types of bulk material up to a product temperature of 80° C. Components: Transmitting and receiving antennae High frequency antenna cable LB 356 evaluation unit Polypropylene chute (360 mm x 250 mm, height 350 mm) including mounting devices for the antennae and area weight components Options: Area weight measuring device consisting of scintillation counter and radiation source in a shielding container Typical installation The chute is installed directly in the product stream or as a by-pass. A steady filling of the chute during the measurement process must be guaranteed. Sensors are installed on the mounting devices at the chute. The evaluation unit is installed close to the horn antennae, limiting the length of each HF-cable to a maximum of 2 metres. The shorter the cable connections between the horn antennae and the evaluation unit, the better the stability of the instrument.

Using the LB356 for the measurement of moisture in pipelines

Micro-Moist LB356 can perform in-line measurement of moisture or dry matter in liquid and paste-like products. For this purpose, Berthold supplies a flow-through cell with a nominal diameter of 50 mm which can be easily inserted into the process line. Micro-Moist has proved itself over many years in the foodstuffs industry in determining the moisture or dry matter of butter, cheese products, and caramel.

Components

• Flow-through cell, DN 50, PN 10 bars, PTFE lining
• HF antenna cable
• LB 356 evaluation unit

Typical installation The detector cell is best installed in a vertical pipe under pressure. The fitting is done by dairy screw necks or tri-clamps. The evaluation unit is installed close to the flow cell, limiting the length of each HF cable to a maximum of 2 metres. The shorter the cable connections between the flow cell and the evaluation unit, the better the stability of the system.

Application Notes

• Moisture in Wood Chips (LB356)

for more information, email

SE Asia and Australasia: industrial@berthold.com.au

North America: usinfo@berthold.com.au

Europe: euroinfo@berthold.com.au

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