A material thermal property database was developed for use in Consolidated Model of Fire and Smoke Transport (CFAST) simulations performed in support of fire investigations. The database includes thermal properties for interior surface materials; ignition, metal, and plastic target materials; and damage target materials. CFAST assumes that thermal properties of interior surface and target materials remain constant throughout the course of the fire. In reality, these properties vary with temperature. Assuming ambient temperature properties remain constant may result in significant errors in the heat conduction calculations. This paper presents the results of Fire Dynamics Simulator (FDS) compartment fire simulations to evaluate the effect on room temperature predictions of using constant versus temperature-dependent thermal properties for the gypsum board on walls and ceiling. The simulations show that assuming ambient temperature properties will overestimate the room temperature during the peak burning and decay periods of the fire. Fidelity of the predictions can be improved by increasing the specific heat in the constant property simulations to account for the gypsum dehydration energetics indirectly. The paper describes methodologies developed to estimate effective constant thermal properties for ignition and metal target materials and provides examples to illustrate their application. The methodology for ignition target materials relies on FDS heat conduction simulations of a series of ignition experiments conducted in the Cone Calorimeter. An evolutionary method is used to obtain values for thermal conductivity, specific heat, and ignition temperature that optimize agreement between calculated and measured ignition times. The approach to estimate effective thermal properties of metal target materials is similar. First, FDS and temperature-dependent property values of the metal are used to determine the time for the target surface to reach the melting point for a range of heating conditions. Next, an evolutionary optimization method is used to estimate constant property values that result in best-fitting FDS target temperature rise predictions.

A study was performed to determine through computer fire modeling up to what extent a room fire in which a flat screen television is the first major item ignited is more likely to result in flashover if the television casing is not treated with flame retardants. This was accomplished by quantifying the risk of flashover in a living room or bedroom due to a fire in which a flat screen television is the first major item ignited, and by calculating the ratio of the risk measures for televisions with untreated casing versus those with flame retardant treated casing. This ratio is an indication of the increased likelihood of flashover should flame retardant treated television casings be replaced with untreated casings. The results of the risk quantification indicate that living room fires initiated with a flat screen television are between 4.2 and 15.2 times more likely to result in flashover when the casing is not treated with flame retardants compared to a flame retardant treated television. For fires in the (master) bedroom, the relative likelihood is between 4.1 and 15.5. The relative likelihood of flashover is slightly lower for apartments than for single family homes.The calculated ratio varies depending on the assumed probability that the ignition source is sufficiently severe to ignite a television with flame retardant treated casing.fire modeling, fire risk assessment, flame retardants, flashover, television fires | INTRODUCTIONComparative furniture calorimeter and room fire testing over the past 35 years has demonstrated that television (TV) sets in the United States are much more difficult to ignite and, when ignited, release heat at a significantly lower rate than European TVs. [1][2][3][4][5] The primary reason for the difference in fire performance is that in the United States, the casing needs to have a UL 94 V-0 rating while a less stringent HB rating is required in Europe. To achieve a V-0 rating, the casing material, typically high-impact polystyrene (HIPS) or acrylonitrile butadiene styrene (ABS), needs to be treated with flame retardants (FR). FR treatment is generally not needed to meet the HB rating requirements.Table 1 shows some select results from three comparative studies. The peak heat release rate (HRR) is indicative of the hazard associated with a TV fire. Table 1 indicates that total mass loss measurements in the earlier studies, involving then popular cathode-ray tube (CRT) TVs, are comparable to the mass loss measurements from the recent study, which involved now popular flat screen TVs. It should be noted that the TV contents were removed prior to testing