A simple procedure is presented for estimating room temperature and the likelihood of the occurrence of flashover in an enclosure. The engineer can use the results for quantitative estimations of the effects of building design and fire load on the tendency for flashover as defined by a temperature limit.T HE ABILITY to predict the onset of flashover would be a useful tool for the designer, code official, or others concerned with building firesafety. A large amount of effort is being expended at the moment in the fire research community directed at precisely this end. Recent advances in fire modeling have made possible the development of computer simulations of the growth and spread of fire in an enclosure. It is now possible to predict the outcome of a fire from a burning object in a single compartment given information about the geometry of the room, properties of the wall material, the nature and size of the ignition source, the fuel array and its burning characteristics, etc. Examples of the input requirements and an assessment of the agreement between the predictive results and experimental data are available.l.2.8Although very useful in elucidating the physics and chemistry of fire growth and spread, these models tend to be extremely complex and will require several more years of development before they can be routinely utilized by the practicing fire safety specialist. What is needed in the interim are formulae or procedures for analysis which, while remaining tractable, will yield good estimates of the behavior of the fire. This approximate or coarser approach will obviously be less accurate than the complete computer solutions but will have the benefit of being able to be applied very simply yet still preserve the elements of a rational approach to hazard 98
This paper describes an experimental study of the dynamics of smoke filling in realistic, full-scale, multiroom fire scenarios. A major objective of the study was to generate an experimental data base for use in the verification of mathematical fire simulation models. The test space involved 2 or 3 rooms, connected by open doorways. During the course of the study the areas were partitioned to yield four different configurations. One of the rooms was a burn room containing a methane burner which produced either a constant energy release rate of 25, 100, or 225 kW or a time-varying energy release rate which increased linearly with time from zero at ignition to 300 kW in 10 min. An artificial smoke source near the ceiling of the burn room provided a means for visualizing the descent of the hot layer and the dynamics of the smoke filling process in the various spaces. The development of the hot stratified layers in the various spaces was monitored by vertical arrays of thermocouples and photometers. A layer interface was identified and its position as a function of time was determined. An analysis and discussion of these results are presented.
An experimental procedure is described which can be used to derive data relevant to the prediction of ignition and flame spread on materials. This procedure offers a direct method for determining material property data suitable for use in mathematical fire models. The apparatus utilizes a radiant heat source capable of supplying up to 6.5 W/cm2 to a vertically oriented specimen. The test results pertain to piloted ignition of a vertical sample under constant and uniform irradiation and to lateral flame spread on a vertical surface due to an external applied radiant heat flux. The results can be used to display the maximum velocity and ignition time as a function of irradiance. Critical or minimum irradiances for spread and ignition are determined. An empirical correlation, based on heat conduction principles, is found to correlate the ignition data and also provides a more general interpretation for the flame spread results. Further analyses of the data yield effective values for the thermal inertia of the material (kρc), its ignition temperature, and a parameter related to flame temperature. These parameters appear to be phenomenological constants for each material, rather than factors dependent on the apparatus. Results are presented for a wide range of materials. Suggestions for extending the results to other flame spread conditions are presented.
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