Abstract
Six portable direct-reading instruments for measuring industrial aerosols were evaluated with respect to bias and precision. The six instruments were: the Sibata P5, Simslin II, TM-digital, RAM-1, TSI3500 and RDM 201. As a reference, total dust was determined using an open 37 mm cassette and respirable dust by means of sampling with a cyclone. Both commonplace and toxic industrial aerosols were selected as the test aerosols. Some of the tests were performed on aerosols simulated with a generator and a dust chamber and some were performed on aerosols in sintering plants, mines and smelters. The zero drift, the reference unit drift and the flow rate drift were recorded during each test run. These drifts were also examined in a special laboratory experiment with respect to temperature changes. None of the six tested instruments gave the same readings as the filter method, but four of them could be calibrated to yield precision less than 25% for a given aerosol. The fifth instrument, i.e. the Simslin II, displayed somewhat greater precision, and the sixth, the RDM 201, displayed precision much greater than 25%. Wide differences in factory pre-calibration were found among instruments of the same model.