Annals of Occupational Hygiene Advance Access originally published online on November 2, 2007
Annals of Occupational Hygiene 2007 51(8):725-738; doi:10.1093/annhyg/mem053
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Published by Oxford University Press on behalf of the British Occupational Hygiene Society
Evaluation of a Proposed Area Equation for Improved Exothermic Process Control
1 Division of Surveillance, Hazard Evaluation and Field Studies, National Institute for Occupational Safety and Health, 4676 Columbia Parkway, MS-R14, Cincinnati, OH 45226, USA
2 Department of Work Environment, University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, USA
* Author to whom correspondence should be addressed. Tel: +1-513-841-4212; fax: +1-404-929-2647; e-mail: jmckernan{at}cdc.gov
Our understanding of heat transfer and meteorological theories and their applications for engineering control design have been refined since the collective work in ventilation engineering for manufacturing process was published by Hemeon in 1955. These refined theories were reviewed and used to develop a newly proposed equation to estimate buoyant plume area (A). The area is a key parameter in estimating the plume volumetric flow (Q = 
A) required for exothermic process control. Subsequent to developing a theoretical equation for plume area (A), plume velocity and area data were collected in the laboratory using a thermal anemometer and a scale-model exothermic process. Laboratory results were compared to solutions provided by the proposed, American Conference of Governmental Industrial Hygienists (ACGIH) and Hemeon plume area equations to determine which equation most closely matched the laboratory data. To make this determination, either t-tests or Wilcoxon signed-rank tests were conducted (based on examination of data normality) to determine the difference between collected data and solutions from the proposed, ACGIH and Hemeon equations. Median differences and P-values from Wilcoxon signed-rank tests (non-parametric) indicate that the ACGIH and Hemeon plume area equations provide significantly lower values than the laboratory data. However, the proposed equation provided solutions that were not significantly different from the collected data. Results indicate that the plume area equations currently recommended by the ACGIH and Hemeon are not as accurate as the proposed equation over the range of parameters investigated.
Keywords: engineering controls • heat and cold • hot processes • local exhaust • ventilation
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Received June 29, 2007; in final form September 17, 2007