Tobacco Asia

Volume 18, Number 4

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56 tobaccoasia By Thomas Schmid Moisture meters (or moisture analyzers, if you will) are crucial tools in practically every step of tobac- co processing. From whole leaf in the green leaf threshing (GLT) or primary all the way down to testing cigar fillers, expanded tobacco, reconstitut- ed sheet tobacco, final blend, or in-pack moisture, their applications are extraordinarily broad. For that reason alone, moisture meters must be easy to install, calibrate, and operate – besides delivering reliable measurements, of course. A tide of challenges to ensure accuracy Production lines often go through a rapid succes- sion of wildly varying product types, each one of them imparting their very own specifications in terms of targeted moisture and other components. "Moisture is a complex parameter," in the words of Stefan Tordenmalm, near-infrared (NIR) product manager at Swedish company Perten Instruments. This view is shared by André Tews, general man- ager of Tews Elektronik in Hamburg, Germany. "Tobacco is a natural product, therefore leaves and cut tobacco are very compressible and also vary in surface structure and color, all of which pose chal- lenges [for accurately gauging moisture content]," It's color where peril lurks… More or less pronounced color variations can in- deed impede measurement accuracy, particularly when a meter using NIR (near infrared) sensor technology is deployed. "Infrared moisture me- ters on the whole are affected by color changes in the tobacco. So what we're trying to do in the de- velopment of our moisture meters is to minimize that effect by using various hardware and software adjustments to make the machine less color-sensi- tive," explained Sean Herrington, managing direc- tor of Moist Tech Corporation. …or is it ambient light? Another area that needs to be addressed especially when NIR sensors are used is ambient light from natural or artificial sources in the environment. A sensor should ideally ignore the ambient light con- ditions; or at least compensate accordingly to en- sure accurate readings. "Our moisture meters are insensitive to ambient light, so when conditions do change it won't affect the instrument," assured Herrington. But what about core moisture? Measuring surface moisture is one thing, but it does not take into account the often substantial- ly higher core moisture, which depending on the product, can be an important parameter. While NIR sampling beams typically cannot penetrate into the core, microwave-based machines like the ones developed by Tews Elektronik might just be Moisture Measurement Matters Brabender MT-C Moist Tech's model 828

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