MICROWAVE MOISTURE SENSOR

Product moisture is essential to manufacturing and processing web products such as tissue, paper, paperboard, nonwovens, textiles and plastics. Microwave-absorption technology has been used extensively to determine moisture on the web, but limited resolution restricted its use to measuring large quantities of water. These limitations prevented accurate measurement of thinner products or grades with low moisture levels.

Aqualot HMF sensors use patented technology to detect the smallest amounts of water possible with extreme accuracy and degree of stability, enabling these sensors to measure thin materials such as light paper and nonwoven grades without accuracy being affected by color and composition.

The Aqualot HMF moisture sensor consists of two parts, which together form a resonance chamber, and the product passes through the center of this divided chamber. A microwave emitter stimulates two standing waves in the resonance chamber. One wave corresponds to the absorption wavelength of the water molecules in the microwave spectrum, and the second wave serves as a reference.

Contrary to traditional absorption technique, the Aqualot HMF moisture sensor evaluates the shift in the resonant frequency of the two standing waves with respect to one another instead of the attenuation of the microwaves by the quantity of water molecules in the measuring gap.

This patented microwave resonance principle is virtually insensitive to changes in product composition, an advantage that keeps product-specific calibrations to a minimum. Also, the device has the ability to resolve to an exceedingly high degree the lowest percentages of moisture, thereby extending the use of microwave technology beyond traditional measuring techniques.