The program objective was to develop and evaluate methods for the continuous measurement of gaseous emissions from stationary sources, specifically in large or complex ducts where total flow processing techniques are not practical. This report is concerned with the measurement of mean gas concentrations in rectangular ducts. Work consisted of a review of related programs, development of a computer program to assess stratification levels and evaluate sampling techniques, formulation and evaluation of point sampling methods for continuous monitoring, development of a multi-port continuous gas sampling probe, and field demonstration of hardware and techniques. Results showed that emissions can be accurately monitored using as few as one flow sensor and one sampling probe, even in the presence of significant velocity and compositional stratification, although stratification levels were too high for single point samples to be acceptable. It was shown for all data examined that good accuracy can be attained by taking a spatial concentration average -- flow proportional sampling is not required. The field demonstration verified the acceptability of the proposed methodology.

"EPA 600-2-75-012." "July 1975." Cover title. Appendices included. Bibliographical references included. PB-245 024.