Fire Safety Science Digital Archive

The Swedish Fire Research Board and the U.S. Federal Emergency Management Agency are sponsoring a project to further the understanding of the basic mechanisms involved, as well as to support the development of standards for and to seek ways of improving the performance of portable fire suppression systems used by fire departments. This effort includes both experiments and computer model development work. This paper describes a physically based computer model developed to simulate one aspect of the problem: the manual suppression of post-flashover fires. This includes: (1) a discussion of the physical basis behind the model; (2) a comparison of model predictions with available experimental data; and (3) an analysis of fire suppression effectiveness using the model. The analysis concludes that, when direct assess and extinguishment of the burning fuel is not possible, improved fire control occurs with water sprays having a Rosin-Rammler distribution of droplet sizes and volume medium drop diameters in the 0.15 to 0.35mm range. This agrees with available experimental data. It is also shown that fire fighting venting and standoff distance requirements may lead to more severe fires requiring more water for control. Finally, the analysis shows that venting and water spray induced air/gas flow effects also serve to channel hot steam and gases away from the fire-fighter adding to his safety. Additional experimental work is also recommended before all these conclusions can be considered definitive.