| Popis: |
A rotating drum dustiness tester was used to characterize variability of dustiness in dependence of type and mass of test material, testing time, and surface adhesion. Powders of six common materials entered the study: bentonite, barium sulphate, talc, Aloxite, carbon black, and coal. Except for coal, dustiness was in general positively correlated to the mass of powder under testing. Surface adhesion tended to be aAected from the type of test material. For a fixed dust dispersion time (180 sec) the dependence of dustiness on time was characterized in terms of the time required to arrive at the median of the cumulative distribution of mass delivered at the outlet of the drum. In general the time required was positively correlated to the mass of material under testing. A three-parameter multiplicative model for dustiness potential was developed for two of the test materials (bentonite and barium sulphate). The model included surface adhesion, time, and mass of material under testing as predictors. The model was highly significant ( p < 0.001) and accounted for more than 80% of the observed variation in dustiness. It is concluded that for dustiness testing to become useful a careful control of all the operating parameters are required in order to have reproducible tests. Therefore standardization of the method is essential. # 1999 British Occupational Hygiene Society. Published by Elsevier Science Ltd. All rights reserved. |
