COMPARISON OF RESPIRABLE SAMPLERS TO DIRECT-READING REAL-TIME AEROSOLMONITORS FOR MEASURING COAL-DUST

Three types of respirable dust samplers were positioned side-by-side a s area samplers within three coal-fired electric power generating faci lities. Respirable dust readings were taken using two direct-reading a erosol monitors (MIE PDM-3 Miniram and the TSI Model 8520 Dust Trak) a nd the results compared to side-by-side respirable coal dust concentra tions. Both direct-reading instruments use optical sensors far detecti ng dust concentrations, and in this study the air was passed through a 10-mm cyclone prior to detection. Respirable samples were collected u sing a 10-mm cyclone with a 5-mu m PVC filter connected to a constant flow pump calibrated at 1.7 L/min. The samples were collected for fift een 8-hr shifts over a one-month period. Respirable dust concentration s ranged from 0.23 to 10.83 mg/m(3). The responses of each of the dire ct-reading instruments were compared to the respirable values. Neither of the two direct-reading instruments provided values that were ident ical to each other or the respirable samplers, but regression analyses indicated high coefficient of determination (R(2)) values (0.85 and 0 .94). Other statistical methods (analysis of variance, pair wise t-tes ts, and mixed effect models) found no significant differences (p>0.05) between the data sets for the direct-reading instruments and the resp irable samples. II was concluded that the two direct-reading instrumen ts can be used to measure respirable coal dust.