Comparison of Particle Size Determined with the Coulter Counter and by Optical Microscopy

The success of the Coulter counter in other fields has led to its being considered for use in the counting and sizing of dusts in industrial hygiene. This study attempts to derive a relationship between microscopy measurements and measurements made with the Coulter counter. Particle size distributions for selected dusts were derived from measurements with a Coulter counter and by microscopy. The data and results of this study show that particle size based on microscopy will in general differ from that determined with the Coulter counter. It also suggests that errors in excess of 500% are possible if particle size volume distributions are calculated by transforming projected area distributions.