Reproducibility of Aerosol Photometer, Midget Impinger, and Membrane Filter Counts for Limestone and Coal Dusts

The curves of error for dust counts were developed for counts made by aerosol photometer, midget impinger, and membrane filter procedures. The interrelation of counts by different procedures were studied. With limestone dust, the counts by the aerosol photometer were most reproducible and those by midget impinger were least reproducible. The type of dust and the particle size affected the comparability of counts by the different procedures.