Tests of sampling systems for test aerosols in a dust channel and in ambient air. II

The paper reports on tests of filter devices, carried out in sampling systems by using flow of smoke, test aerosols, and ambient air, which showed that the horizontal elutriator in an optimal design was best suited for the measurement of the total respirate particulate matter. It is reported that systems that are equipped with a flow plate in front of the intake opening showed more favorable flow conditions in the aspiration area and showed a higher separation efficiency than sampling systems without such a plate. Finally, attention is given to tests run with a modified Andersen nonviable impactor which suggested that particulate losses on the upper nozzle plate and in the casing are largely avoided by a modification of the intake cone and the three upper impaction stages.