Empirical determination of the error in the ACGIH method of predicting airflow distribution in two ventilation systems.
Seattle, WA: University of Washington, 1995 Jun; :1-123
Ventilation systems are important in reducing worker exposure to airborne contaminants. To do this job sufficiently, ventilation systems must deliver the correct airflow to each hood according to its requirements. Proper airflow distribution is achieved through proper design, installation and maintenance. Proper design requires an accurate predictive model of the system. The most commonly used model is that described by the American Conference of Governmental Industrial Hygienists (ACGIH) in Industrial Ventilation: A Manual of Recommended Practice. The efficacy of this predictive model, which is based on published loss coefficients, has not been documented in the field and published literature. It is the purpose of this field study to compare the observed loss coefficients to those published by the ACGIH in the Industrial Ventilation manual. In this study, the error is determined by analyzing the differences between the observed sum of loss coefficients and the sum of published loss coefficients for each branch. Error in the loss coefficients is important because it results in a proportional error in airflow distribution. The data analysis for this work focused on the coefficients for different components (e.g. hoods, elbows) in an effort to identify the sources of deviation from the predicted sum of coefficients. That analysis indicated substantial discrepancies between the predicted and observed sums of loss coefficients which may translate into unacceptable shifts in airflow distribution.
Ventilation; Industrial-ventilation; Ventilation-systems; Exhaust-ventilation; Air-flow; Air-contamination; Airborne-particles; Equipment-design; Models
Jeanne S. Hoppe, University of Washington, School of Public Health and Community Medicine, Department of Environmental Health, Room F226D, Box 357234, Seattle, WA 98195-7234
Empirical determination of the error in the ACGIH method of predicting airflow distribution in two ventilation systems
University of Washington, Department of Environmental Health, Seattle, WA