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Quantitative Backdraft Experiments.

pdf icon Quantitative Backdraft Experiments. (583 K)
Fleischmann, C. M.; Pagni, P. J.; Williamson, R. B.

International Association for Fire Safety Science. Fire Safety Science. Proceedings. 4th International Symposium. July 13-17, 1994, Ottawa, Ontario, Canada, Intl. Assoc. for Fire Safety Science, Boston, MA, Kashiwagi, T., Editor(s), 337-348 pp, 1994.


National Institute of Standards and Technology, Gaithersburg, MD


fire research; fire safety; fire science; backdraft; experiments; compartment fires; explosion hazards; gravity current


This paper focuses on 17 experiments in a 1.2 m by 1.2 m by 2.4 m compartment. A methane burner, flowing at either 70 kW or 200 kW, was ignited inside a closed compartment and burned until the initially available oxygen was consumed. After the fire self-extinguished, the burner was left on allowing the unburned fuel mass fraction in the compartment to increase. After removing a hatch, covering a 1.1 m wide by 0.4 m high slot opening, a gravity current entered the compartment. It traveled across the floor, mixed with the unburned fuel, and was ignited by a spark near the burner. After mixture ignition, a backdraft occurred as a deflagration ripped through the compartment culminating in a large external fireball. Histories recorded prior to backdraft included: fuel flow rates, upper layer temperature, lower layer temperatures, upper layer species concentrations for O2, CO2, CO, and HC. Data collected to quantify the backdraft included opening gas flow velocities and compartment pressures. Results indicate that unburned fuel mass fractions >10% are necessary for a backdraft to occur.