KERN DLB 160-3A Operating Instructions Manual

Also see for DLB 160-3A: Operating instructions

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KERN DLB 160-3A Operating Instructions Manual Manual pdf 49 page image

DLB_A-BA-e-1110 4912 General information concerning moisture analysis12.1 ApplicationIn all cases where moisture is added to or removed from products, a fast determinationof the moisture content is of enormous importance. For countless products the moisturecontent is not only a quality feature but also an important cost factor. Very often fixedlimits for moisture content apply to the trade in industrial or agricultural goods as well aschemical or food products which are defined by terms of delivery and generalstandards.12.2 BasicsMoisture does not only mean water but includes all substances that evaporate whenheated up. In addition to water this includes,- Fats- Oils- Alcohol- Solvents- etc...There are various methods to analyse moisture in a product.KERN MLB uses a method called thermogravimetrics. In accord with this method, thesample is weighed before and after heating, determining the material moisture bylooking at the difference.The conventional drying chamber method follows the same principle, with the exceptionthat this method requires a considerably longer measuring period. . In accord with thedrying chamber method, the sample is heated from the outside to the inside by a hot aircurrent, so as to remove the moisture. The radiation applied in the KERN DLBpenetrates mainly the sample in order to be transformed inside it into heat energy thatis, warming from the inside to the outside. A minor amount of radiation is reflected bythe sample, a reflection that is less in dark samples than in light-coloured ones. Thedepth of penetration of the radiation depends on the permeability of the sample. Insamples of low permeability the radiation only penetrates the outer layers of thesample, possibly resulting in imperfect drying, incrustation or burning. For that reasonthe preparation of a sample is of great importance.12.3 Adjustment to existing measuring methodQuite frequently the KERN DLB replaces a different drying method (such as a dryingchamber) as the KERN DLB achieves shorter measuring times during a simplifiedoperation. For that reason the conventional measuring method must be matched to theKERN DLB in order to achieve comparable results.• Carry out parallel measurementLower temperature setting for KERN DLB than drying chamber method• Result of KERN DLB does not match reference- Repeat measurement with changed temperature setting- Vary shutoff criterion