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Examining the effectiveness of water suppression for mitigating backdrafts



Ryan Falkenstein-Smith, Thomas Cleary


An analysis of the backdraft phenomenon's mitigation from water suppression is con- ducted in a 2/5th scale compartment. Different volumes of water were introduced via a ceiling- mounted misting nozzle into the compartment, which hosted conditions conducive to backdraft (i.e., a fuel-rich, oxygen-depleted, and high-temperature environment). The effect of water suppression was examined using two metrics indicative of backdraft: 1) the flow of the gravity current mixing into the compartment and 2) the total heat release of the resulting fireball. The gravity current was analyzed using density estimations obtained from phi meter measurements at six positions within the compartment. The total heat release of each observed backdraft was estimated from carbon dioxide and carbon monoxide concentrations in the exhaust duct residing over the compartment. Backdrafts were still observed in instances where water suppression was implemented. In some cases, water suppression increased fuel concentration around designated ignition sources. Upon entering the compartment, the gravity current's velocity declined as more water was introduced, allowing more fuel to escape and less to be combusted in the ensuing fireballs. Measurements were validated from comparisons to established empirical formulas and orthogonal measurements.
Conference Dates
March 19-22, 2023
Conference Location
College Station, TX, US
Conference Title
13th United States National Combustion Meeting


Backdraft, Water Suppression, Gravity Current, Total Heat Release


Falkenstein-Smith, R. and Cleary, T. (2023), Examining the effectiveness of water suppression for mitigating backdrafts, 13th United States National Combustion Meeting, College Station, TX, US, [online], (Accessed May 17, 2024)


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Created March 19, 2023, Updated September 8, 2023