Experimental Investigations of Fire Spread and Flashover Time in Office Fires

Abstract

The characteristics of, prediction models for, and experimental data pertaining to flashover in full-scale room fires were first reviewed. Then, initiation, growth, full development, and decay of three office fire scenarios were experimentally explored using a 10 MW fire test facility and continuous online combustion gas analysis. The conditions for flashover were investigated and compared with correlations in the literature. The model office compartment is an aerated lightweight concrete structure with dimensions of 5 m  6 m and with a net room height of 2.4-3.3 m. The results show that the measured minimum heat release rate at flashover is consistent with the correlations of Babrauskas [5] and McCaffrey et al. [6]. Based on the fundamental definition of flashover using the 'energy-filling' concept it is possible to predict the flashover time via a case-based reasoning method. However, more work is needed to further validate this concept.

On the Analogy Between Flashover and Thermal Ignition

“…A recent paper in this journal [1] is concerned with flashover, that is, transition from a small and localized fire to one involving an entire enclosure. Such transition is rapid and is accompanied by a sharp increase in heat release rate.…”

“…The authors of [1] discuss flashover as thermal instability and in so doing invoke the classical thermal ignition work by Semenov and Frank-Kamenetskii (F-K). They state:…”

“…Returning to the statement quoted from [1], it is doubtful whether the reference to the boundaries is quite correct. Heat transfer in flashover is largely by radiation, and what distinguishes gas radiation from radiation from a solid is that the former is from within the volume of gas whereas the latter is from the surface only.…”

Experimental Study on the Fire-Spreading Characteristics and Heat Release Rates of Burning Vehicles Using a Large-Scale Calorimeter

“…In fire researches, calorimeters, which can estimate a heat release rate, smoke generation, carbon dioxide, carbon monoxide, and so on, have been widely used for experimental study [2][3][4][5]. In the case of heat release rate, it has been regarded as one of the most important factors during experimental studied since it can be used to calculate the size of the fire and be more easily used in performance-based design (PBD).…”

Experimental study of the influence of interior lining distributions on flashover in the enclosure with different ceiling structures

“…It is affected by the thermal property of interior linings, ventilation, the volume of enclosures, the height of soffit, and the chemistry of the hot gas layer. The phenomenon of flashover has been extensively studied . A great number of definitions to flashover have been developed based on experimental studies.…”