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 x 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.

Flammability, fire performance, and thermal stability of short glass fiber reinforced polyamide-6 and polyamide-66 containing halogenated and halogen-free flame retardants (FRs) were compared. Flammabilities were assessed by limiting oxygen index tests and UL94 classifications. Fire behavior was evaluated by mass loss cone calorimetry, a bench-scale tool, to assess fire performance of materials. Halogen-free, phosphorus-based FRs were shown to perform superior to halogenated counterparts on the basis of important fire properties, peak heat release rate, time to ignition, and fire growth index. Moreover, thermal stabilities were maintained at an acceptable level as a clear advantage of halogen-free FRs.

The use of mathematical models to predict the thermal resistance of polymer-based, intumescent coatings are reviewed and their limitations are discussed. A mathematical model is derived to describe the developing temperature profile across an intumescent coating when exposed to a radiant heat source. The model includes the effects of: the endothermic and exothermic reactions; convective heat transfer as degradation gases are transported through the coating; radiation heat transfer across the developing porous solid; and the increase in thermal resistance as gases are formed and the coating expands. The model predictions are compared with experimental data from the heating of epoxy-based and vinyl acetate-based intumescent coatings in a cone calorimeter. A sensitivity analysis is performed to show the effect of the thermal characteristics of the coating on the thermal resistance of the material. The application of the model to newly developed intumescent coatings is discussed.

Zinc stannate and hydroxystannate are used as synergists in fire-retardant systems in conjunction with halogenated species where their behavior is generally considered to be similar to antimony-containing synergists while offering the additional properties of smoke suppression and relative nontoxicity. The literature most often compares relative synergistic behaviors qualitatively but this article determines such behavior quantitatively using Lewin’s synergistic effectiveness parameter, E_S, calculated from sample limiting oxygen index (LOI) data. Flame-retardant formulations comprising zinc stannate (ZS), zinc hydroxystannate (ZHS), or antimony III oxide (ATO) in combination with selected and polymer-compatible bromine-containing flame retardants were formulated in commercial grades of poly(vinyl chloride) (PVC)), thermoset polyester resin, and polyamide 6. PVC formulations simulated both commercial cable and plastisol applications and comprised either a phthalate or aryl phosphate ester as plasticizer in combination with selected synergists. All formulations were subjected to flammability testing using LOI, UL94 (vertical sample mode), and cone calorimetric (including smoke analysis) methods. For all PVC/synergist combinations containing the phthalate plasticizer, synergy was evident with 2.0 > E_S > 1.0 and a relative effectiveness order ATO > ZHS > ZS. Zinc borate present as a cosynergist also has a quantifiable, positive effect. In the presence of the phosphate ester plasticizer, the reverse order is observed with marginal levels of synergy being evident (1.2 > E_S > 1.0). In polyester resin formulations, ATO and ZHS exhibit similar levels of synergy when present with dibromoneopentyl diglycol with the former being superior when decabromodiphenyl ether is the flame retardant. However, in all polyamide 6 formulations, the highest levels of synergistic effectiveness are observed (E_S ≥ 5.0) with ZS. Maximum values of E_S correspond to a molar ratio of Sn/Br<0.3 suggesting the formation of SnBr₂ and SnBr₄ as the effective flame-retarding species.

This article presents a series of experiments on benchmark fire suppression. The experiments were performed in a controlled environment, utilizing a cylindrical object or calorimeter centered above a 2 m diameter pan filled with kerosene-based hydrocarbon fuel, JP8. The experimental setup and procedure for gathering data on water suppression performance are presented. The characteristics of the nozzles used in the experiments are presented as well. The experimental results provide the boundary condition and temporal data necessary for validation of the fire suppression models used. The article also includes simulation results on the fire suppression experimental tests. The suppression simulations were carried out using a numerical model based on a Temporally Filtered Navier-Stokes (TFNS) formulation coupled with a Lagrangian model for droplets, which includes detailed descriptions of the interaction between the water droplets and the fire plume. The results from both experiments and simulations suggest that the criterion for complete suppression depends on a combination of factors including the mass flow rate (or nozzle diameter), nozzle operating pressure, and calorimeter presence. A critical regime which distinguished the regions of suppression and no-suppression in the domain of the mass flow rate versus operating pressure is found.

A time-dependent, moving boundary, multiphase Navier–Stokes model is developed to study the effects of aqueous foam with high air-to-water volume ratio (expansion ratio, Ex) on a jet diffusion flame. The flame is formed by combusting a steady flow of propane gas. Both the shape and velocity of the foam surface are affected by evaporation and injection rates, and are obtained by volume of fluid method. The evaporation at the advancing foam front releases water vapor as well as a significant amount of air into the flame. At low foam injection rates, simulations show that the flame spreads along the foam surface and is not extinguished. This is because the injection rate is comparable to the evaporation rate, which causes cooling but prevents the foam from advancing into the flame. However, at high foam injection rates, the simulations show that the flame lifts from the burner lip and the flame is reestablished above the rising foam surface due to the continued supply of the propane gas. Thus, the foam extinguishes the flame locally in its path by increased smothering as it rises towards the top of the burner. Both the smothering and evaporation effects are found to be important.

A coupled thermo-mechanical model is presented for calculating the compressive strength and failure of polymer laminated composites with thermal barrier when exposed to fire. Thermal barriers are used to protect composite structures from fire, and this article presents a model for calculating the improved structural survivability under compression loading. The thermal component of the model predicts the through-thickness temperature profile of the composite when protected from fire using a passive thermal barrier insulation material. The thermal analysis is coupled to a mechanical model that calculates the loss in compressive strength with increasing temperature and heating time. The model predicts the strength loss and failure time of an insulated composite supporting a static compressive load when exposed to fire. The accuracy of the model is evaluated using failure times measured in fire-under-compression load tests on a woven E-glass/vinyl ester composite protected with a passive thermal barrier. The model predicts reductions to the failure time with increasing heat flux (temperature), applied compressive stress, and reduced insulation thickness, and this is confirmed by experimental testing. It is envisaged that the thermo-mechanical model is a useful analytical method to design thermal barrier material systems to protect composite structures exposed to high temperature or fire.

Flame retardants including magnesium hydroxide (MH) and huntite hydromagnesite (HH) were used to develop halogen free flame retardant (HFFR) compounds based on ethylene vinyl acetate (EVA) for wire and cable applications. Cone calorimeter and limiting oxygen index (LOI) results show that cross-linking affects not only mechanical properties, but also flame retardancy. Consequently, flame retardancy is mainly influenced by type of flame retardants and mixing ratio of base polymers and to a lesser extent by cross-linking. Tensile strength increased with increase of MH, while elongation at break decreased with increase of MH in cross-linked formulations. On the other hand, elongation at break increased with increase of HH while tensile strength decreased with increase of HH in cross-linked formulations. HFFR compounds with tensile strength of 12 MPa, elongation at break of 200%, LOI of 40% was developed to meet the stringent specifications of wire and cable industry.

The thermal insulation properties of thermoplastic polyurethane elastomer nanocomposites were characterized at different heat fluxes. Thermoplastic polyurethane elastomer was modified with different loadings of montmorillonite nanoclays and carbon nanofibers (CNFs) via twin screw extrusion processing. The addition of nanoparticle into thermoplastic polyurethane elastomer resulted in the formation of a char layer and modified the thermal insulative properties of the material. It was found that thermoplastic polyurethane elastomer with 10 wt% CNFs and with 5 wt% nanoclays gave the best thermal performance with respect to protecting a substrate. The surface temperature of the thermoplastic polyurethane elastomer-clay nanocomposites did not vary much with addition of clay particles while the surface temperature of the thermoplastic polyurethane elastomer-CNF nanocomposites varied more substantially. Some of the trends in surface and substrate temperature measurements with nanomodification can be described using a simple energy balance model that takes into account the basic heat transfer mechanisms.

The present article deals with the experimental study to investigate the effects of tunnel slope on the critical velocity in the tunnel fires. The 1/20 reduced-scale model tunnel is adopted on the basis of Froude scaling law. The methanol, acetone, and n-heptane pool fires are used as fire sources with the heat release rate ranging from 1.11 to 1.85 kW, 3.13 to 5.21 kW, and 9.16 to 15.6 kW, respectively. The angle of tunnel slope is varied as five different degrees 0, 2, 4, 6, and 8°. A load cell is used to measure the mass loss rate of the burning fuel. The location of smoke layer is determined on the basis of temperature variation measured at the tunnel ceiling by K-type thermocouples. The present experiments observe the effects of the tunnel slope, fire size, and ventilation velocity on the back-layering distance. The results showed that critical velocity increases with tunnel slope due to the stack effect. The correlation between the critical velocity and the angle of tunnel slope was obtained for the pool fires whose heat release rate was varied with the ventilation velocity.

A new type of nanocomposites consisting of solid 4A zeolites and gaseous fire extinguishing agent of 2-bromo-3,3,3-trifluoropropene (BTP) was fabricated in large scale, in which BTP anchored in the porous zeolites. Laboratory-scale fire extinguishment tests showed that the nanocomposites as additives can greatly improve the performance of conventional sodium bicarbonate (NaHCO₃) dry powder for relatively shorter extinguishing time and smaller amount of agents required. Such an improvement could be ascribed to the simultaneous effect of solid NaHCO₃, gaseous BTP desorbed from the zeolite when presented to higher temperature and the porous zeolite as heterogeneous inhibition of flame free radicals.