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Using CFAST to Estimate the Efficiency of Filtering Particulates in a Building (NIST IR 7498)



Walter W. Jones, Richard D. Peacock


CFAST is a two-zone fire model used to calculate the evolving distribution of smoke, fire gases and temperature throughout compartments of a constructed facility during a fire. The modeling equations used in CFAST take the mathematical form of an initial value problem for a system of ordinary differential equations (ODEs). These equations predict quantities such as pressure, layer height and temperatures as functions of time. The model transports species produced during pyrolysis as well as the products of combustion. Eleven species are followed by the model. They can be categorized as non-reacting, particulate, reacting, and those which can agglomerate and settle. The species are: nitrogen, oxygen, carbon monoxide, carbon dioxide, hydrogen cyanide, hydrogen chloride, fuel in vapor form, soot, trace species and water vapor. A new feature of the model (version 6.1) is the capability to filter trace species and soot which flow through a fan system. Filtering is implemented through the routines that solve the ODE’s. Soot and trace species which are removed from the airstream are deposited on the filter.
NIST Interagency/Internal Report (NISTIR) - 7498
Report Number


smoke movement, environmental assessment, species filtering, HVAC


Jones, W. and Peacock, R. (2008), Using CFAST to Estimate the Efficiency of Filtering Particulates in a Building (NIST IR 7498), NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed June 19, 2024)


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Created April 30, 2008, Updated June 2, 2021