We investigated the effect of ventilation rate, ventilation configuration, fire elevation, and the presence of a plenum (suspended ceiling) on the fire compartment temperatures during forced ventilated methane gas fires (100-400 kW). We found that with low air-inlet positions, fires with ventilation rates greater than 2-3 times the stoichiometrically required air (referred to here as well-ventilated fires) produce twolayer temperature profiles; fires with a lower ventilation rate (underventilated fires) produce single-layer profiles with a temperature gradient. Higher temperatures throughout the enclosure are seen in underventilated fires as compared to well-ventilated fires. We observed that high air-inlet locations perturb the two-layer temperature profile of the well-ventilated fire, cooling the upper layer and heating the lower layer. For underventilated fires, high air-inlet locations lower temperatures in the enclosure but do not perturb the profile shape. Elevated fires and fires in a compartment with a plenum were seen to behave similarly for the same distance from fire base to ceiling, producing hotter layers the shorter the distance.

Force-ventilation compartments are a common environment for fire growth in sealed or high-rise structures. Currently, no method exists for reliably estimating the fire hazard in these enclosures. Using data from compartment fires in the forced ventilation facility at the Lawrence Livermore National Laboratory (LLNL), a simple correlation has been developed following the methods of McCaffrey, Quintiere and Harkleroad. The upper layer temperature rise above ambient, LIT = Tu -Too, is given as a function of: the fire heat release rate, G, the compartment mass ventilation rate, m, the gas specific heat capacity, cp,

Assumptions made and results obtained when applying three fire modeling approaches to study three accidental fires that occurred in single-family dwellings are presented in this article. The modeling approaches used are: a simplified analytical model of fire growth, a zone model (CFAST), and a field model (FDS). The fires predicted are: a house fire of suspected initial location but of unknown ignition source, a small-apartment fire initiated by the ignition of a sofa, which extinguished due to oxygen depletion, and a one-story house fire started by a malfunctioning gas heater. The input to each model has been kept as independent as possible from the other models while consistent with the forensic evidence. The predictions from the models of the fires' characteristics are analyzed in the context of the forensic evidence for each accidental fire to compare the models' predictive capabilities. It is found that in spite of the differences in the sophistication of these three modeling approaches, the results are in relatively good agreement, particularly in the early stages of the fire. Simpler models can be used as a first step towards less approximate modeling or to confirm the order of magnitude of the results from more complex models. The results of this study can be used to reach conclusions about the complexity of the model required to describe a particular fire scenario.

Experimental results are presented of the piloted ignition delay time and the upward flame-spread rate over the surfaces of insulated electrical cables under an externally applied radiant flux. The objective of the experiments was to assess and rank the fire performance of seven types of complex cables commonly used in electrical installations. The experiments were carried out with 46 em long single cables that were suspended vertically and exposed to irradiance levels ranging from 0.5 -2.5 W/cm 2 • Some of the cables had a conducting core, and some did not. A simplified analysis, similar to that developed by Quintiere and coworkers was developed to indentify the parameters that dominate the fire characteristics of the cable. A method similar to that proposed by the above authors was applied to develop flammability diagrams and to define the flame spread properties of the cable materials in an attempt to assess and rank the fire performance of the seven types of cable. It is shown that the method can be successfully applied and that it provides a simple way to rank the cables and to calculate the parameters important to ignition and flame spread in electrical cables. The study also explores the feasibility of predicting the piloted ignition performance of the cable insulations using thermogravimetric analysis (TGA) data in conjunction with the ignition and flame spread formulas by proposing that the surface temperature at which thermal degradation produces pryolyzate is related to the ignition temperature for that particular material. The predicted ignition delay times are compared with experimental results and it is shown that for most polymers, the temperature at which thermal degradation is first Observed can be used to estimate ignition delay times, particularly at high irradiance levels.

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