Demands for the automation of material milling processes accompanied by a lack of automatic methods of continuous measurement of material dispersion were the reasons for initiating activities aimed at developing a device for taking automatic measurements. The dependence of the bulk density of a dust bed on the size of particles was determined on the basis of its theoretical model. This relationship was used for constructing a radioisotope device for continuous dispersion measurements. The results of laboratory experiments, as well as the results of tests on the device in an industrial installation, will be presented.