Abstract: The infrared moisture meter (Model HWS) is an instrument for on-line measurement of moisture in paper. The absorption of two beams in the infrared range are compared using the infrared measuring method. The energy of one beam of wavelength 1.93 μm is absorbed by water molecules and is compared with the energy of a reference one of wavelength 1.78μm uninfluenced by water content. As the pathes of both rays through the tested material are the same, the ratio of the energies arriving at the detector is in direct relation to the moisture content of the material tested.
The infrared moisture meter has been operating continuously for two years with an aocurancy better than 0.5% H₂O.