This report presents the results of two different experimental studies to develop a procedure for designing short roof mounted stacks on industrial buildings. These studies are an extension of ASHRAE RP-136, which investigated the dilution of exhaust gases between vent and intake locations on building surfaces.

PART I of this report presents a flow visualization study carried out in a water channel using dye injection to visualize roof flow patterns over model buildings.

PART II of the report presents a wind tunnel study of the effect of stack height on exhaust gas dilution to roof level air intakes. The wind tunnel experiments complimented the flow visualization study by providing quantitative information on rates of exhaust gas dilution for varying stack height on different building configurations.