A semi-automatic method for the assessment of electric charge carried by airborne dust

This paper describes a new semi-automatic method for the determination of the distribution of the magnitude and polarity of the charge on airborne dust. The aerosol is sampled through an electrified elutriator with the flow split perpendicular to the electric field direction at the exit end. A similar flow rate through both exit parts is achieved by connecting one to a vacuum line and the other to an optical particle counter which counts the numbers of particles in a selected size range. The theory of the operating principle and method of data analysis is described in detail and the results of some tests carried out using coal dust are presented. The possibility of further development to a fully automated system is also discussed.