Hungarian water-content monitors for solids

A special desiccator has been built for drying grain specimens, in which up to 15 specimens can be accommodatedtogether. The temperature in the device is regulated to e 0.5", with the temperature nonuniformity not exceeding 0.5~ The grain specimens are dried at 130 e 2"C, with a drying time of 2 h  5 min. The error of measurement for water content is  0.05%. In recent years, the Hungarian Instrument industry has routinely produced water-content meters for grain, for which test has been obligatory. The HMS has defined a procedure and rules for testing these instruments. The instruments are systematically checked throughout the country. The HMS has also examined the effects of various factors on the accuracy of water-content measurement for grain and flour using dielectric and conductometric methods. Figure I shows how the various factors influence the results of a water-content measurement for grain with an electrical system; the result is dearly influenced by the mass of the grain and the electrophysical characteristics. Tests show that in all dielectric instruments in which the grain is used intact (natural filling) the factors related to the nature of the grain (variety, place of growth, year of harvest) can be replaced by the natural density, as determined by the method of [1]. The effects of thenaturaldensity may be reduced in two ways: by appropriate correction in order to compensate for the natural density and by using specimens of constant mass. Instruments made in Hungary employ both