Computer automation of a dry-dust generating system.
Inhal Toxicol 1994 Mar; 6(2):95-113
A computer controlled system for the automated generation of a dry aerosol in an exposure chamber was developed to minimize variability in aerosol concentration over time. The automated exposure system consisted of a microprocessor controlled stepper motor, a personal computer with analog to digital converter, and a real time aerosol monitor. A computer program was written so that these devices could be used to produce a chamber dust concentration at a level selected. Attempts were made to reduced temporal variation using time series analysis. The mean of the absolute value of the difference between successive measurements was used as an indication of concentration variability for a particular trial. Trials were performed to determine the response of the chamber concentration levels to step changes in generator speed. Typical results for two trials performed to achieve dust concentrations of 10 and 25mg/m3 were presented. Small changes did not coincide well with desired levels, and the data suggested a longer time period necessary to realize the effect of a small speed change on concentration level. The authors conclude that the automated system has potential, although further work is needed to refine inconsistencies.
NIOSH-Publication; NIOSH-Grant; Aerosol-particles; Airborne-dusts; Dust-exposure; Equipment-design; Exposure-levels; Automation; Exposure-chambers
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University of Vermont & St Agric College, Burlington, Vermont