You are here:
A DATA REDUCTION SYSTEM FOR CASCADE IMPACTORS
Citation:
McCain, J., G. Clinard, L. Felix, AND J. Johnson. A DATA REDUCTION SYSTEM FOR CASCADE IMPACTORS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/7-78/132A.
Description:
The report describes a computer-based data reduction system for cascade impactors. The system utilizes impactor-specific calibration information, together with operating conditions and other pertinent information (e.g., stage weights, sampling duration), to determine particle size distributions in several forms for individual runs. The program can handle all commercial round-jet cascade impactors, including common modifications, which are in current use in stack sampling. Other round-jet impactors can be easily substituted. Slotted impactors could be accommodated with slight program revision. A spline technique is applied to fit a curve in the cumulative size distribution obtained from each individual impactor run. The fitted curves have forced continuity in coordinates and slopes. Size distribution averages for multiple runs are made using the fitted curves for interpolation at consistent particle diameters, regardless of the diameters at which the data points fall in the original individual run data sets. After statistical analyses to locate and remove outliers from the data being averaged, variances, standard deviations, and confidence intervals are calculated. The averages and statistical information are available in tables and graphs in several size distribution formats. Averaged data are stored on disks for subsequent use.