Showing papers in "Journal of Fire Sciences in 2005"
TL;DR: In this article, the effects of aspect ratio on critical velocity were analyzed from smoke movement, where the aspect ratio is height/width for a tunnel of rectangular cross-section, and a good agreement has been obtained.
Abstract: In this study, the critical velocity was investigated with various aspect ratios (0.5, 0.667, 1.0, 1.5, 2.0) of the tunnel cross-section in tunnel fires. Reduced-scale experiments were carried out under the Froude scaling using ethanol pool fire. Temperatures were measured under the ceiling and vertical direction along the center of the tunnel. The effects of aspect ratio on critical velocity were analyzed from smoke movement. It has been found that the critical velocity increases with aspect ratio, where the aspect ratio is height/ width for a tunnel of rectangular cross-section. This study used new dimensionless velocity and dimensionless heat release rate parameters considering aspect ratio of the tunnel. The critical velocity varied with the one-third power of the heat release rate for under-medium fires. The results of this study are compared with other small-scale and full-scale experiments. A good agreement has been obtained.
102 citations
TL;DR: In this paper, the pyrolysis and fire behavior of high impact polystyrene (HIPS) containing red phosphorus and melamine polyphosphate was investigated using thermogravimetry coupled with FTIR and MS, respectively.
Abstract: Pyrolysis and fire behavior of high impact polystyrene (HIPS) containing red phosphorus and melamine polyphosphate were investigated. The thermal and thermo-oxidative decomposition were characterized using thermogravimetry coupled with FTIR and MS, respectively. The fire behavior was monitored with a cone calorimeter using different external heat fluxes and determining the LOI. Red phosphorus reduced the heat release in HIPS due to radical trapping in the gas phase. The reduction in effective heat of combustion was accompanied by an increase of incomplete combustion products such as smoke and carbon monoxide. Melamine polyphosphate in HIPS acted in the condensed phase with barrier formation. The heat release rate was reduced, whereas the total heat evolved, smoke and carbon monoxide formation were not influenced significantly. Using both fire retardants, the resulting fire retardancy was characterized mainly by superposition.
77 citations
TL;DR: In this article, flame-retardant nanocomposites are synthesized by melt-blending ethylene-vinyl acetate copolymers with modified layered silicates as nanofillers.
Abstract: Flame-retardant nanocomposites are synthesized by melt-blending ethylene-vinyl acetate copolymers with modified layered silicates as nanofillers. Thermogravimetric analysis performed under air demonstrates a clear increase in the thermal stability of the layered silicate-based nanocomposites. The cone calorimeter is used to investigate fire hazards. The nanocomposites cause a large decrease in the peak of heat release rates. Char formation is the main important factor for the improvement of flame retardancy and its function is outlined. Further improvements of the flame retardancy by combinations of nanofillers and traditional flame-retardant additives based on metal hydroxides are also studied. The nanocomposites based on nanofillers and aluminum trihydrate can be used as very efficient systems for flame-retardant cables. The corresponding results are outlined for a coaxial cable fulfilling the UL 1666 riser test.
59 citations
TL;DR: In this article, a comprehensive discussion on the flammability of organic-inorganic nano-composites is presented based on different fire testing methods, and it has also been found that when traditional flame-retardant additives were added to the nanocomposites, less additive was required to achieve the same level of flame retardancy.
Abstract: A comprehensive discussion on the flammability of organic-inorganic nano-composites is presented based on different fire testing methods. Based on various flammability tests, reduced peak heat release rate, an increased oxygen index, and an enhanced thermal stability were observed, while faster burning rates were found when the nanocomposites underwent horizontal and vertical burning tests. Moreover, it has also been found that when traditional flame-retardant additives were added to the nanocomposites, less additive was required to achieve the same level of flame retardancy.
45 citations
TL;DR: In this paper, the rate of thermal degradation and the thermal resistance of three intumescent fire-retardant coatings under atmospheres of varying oxygen content were measured using thermal gravimetric analysis and differential thermal analysis in an atmosphere of nitrogen or air.
Abstract: Studies are conducted to measure the rate of thermal degradation and the thermal resistance of three intumescent fire-retardant coatings under atmospheres of varying oxygen content. The degradation trials are conducted using thermal gravimetric analysis and differential thermal analysis in an atmosphere of nitrogen or air. It has been found that a low oxygen content in the atmosphere significantly affects the rate of degradation of the char material at temperatures greater than 540°C. The global kinetics of the thermal degradation is modeled using three or four first-order parallel reactions. The degradation of char is modeled using the method of invariant kinetic parameters. The derived kinetic parameters are reported. The thermal resistance of the materials coated on steel plates is determined using a cone calorimeter with controlled oxygen content in the atmosphere. It has been found that the thermal resistance of two of the coatings has been strongly influenced by the oxygen content of the atmosphere;...
45 citations
TL;DR: The mass spectra of brominated epoxy resins collected from pyrolysis at 300 C in the open system under helium are presented and discussed in this paper, where the authors show that bromine-containing aromatics (brominated phenols, alkenyl aryl ether, hydroxyalkyl acyclic acid, and nonbrominecontaining compounds) form high-boiling decomposition products.
Abstract: Brominated epoxy resins cured with diaminodiphenyl sulfone are thermally less stable than nonbrominated analogs. This thermal instability is likely to be caused by the formation of hydrogen bromide which destabilizes the epoxy network. As a result of the reaction of HBr with the epoxy resin, bromine-containing aromatics (brominated phenols, alkenyl aryl ether, hydroxyalkyl aryl ethers), as well as nonbromine-containing compounds form high-boiling decomposition products. The mass spectra of the brominated products collected from pyrolysis at 300 C in the open system under helium are presented and discussed.
30 citations
TL;DR: In this article, the authors show that the addition of organically modified montmorillonite (OMMT) significantly reduces the heat release rates and mass loss rates of the high impact polystyrene (HIPS) composites.
Abstract: The HIPS-montmorillonite nanocomposites are prepared by the static melt intercalation method. XRD analysis indicates that the spacing of the silicate layers increased from 1.51 nm for the untreated montmorillonite to 3.44 nm for the HIPS-montmorillonite prepared by the melt intercalation method. The cone calorimeter test results show that the addition of organically modified montmorillonite (OMMT) significantly reduces the heat release rates and mass loss rates of the high-impact polystyrene (HIPS). Compared with the pure HIPS, the heat release rates of the HIPS-OMMT composites are reduced by 29.5% at 3 phr, 44.8% at 5 phr, 52.1% at 10 phr, and 61.4% at 20 phr levels. The char residues of the composites are examined by the scanning electron microscope (SEM) technique. The fine surface morphology obtained for the residues shows that distinctly separated layers are present in the HIPS-OMMT composites while the original silicate layers remain untouched in the HIPS-untreated montmorillonite mixtures. It is sh...
21 citations
TL;DR: In this paper, the relationship between socioeconomic factors and fire in China is analyzed and the degree of correlation between them is found to be different from that in other countries, and the tendency of fire incidence and serious fire situations occur with the development of economy, which is a distinctive characteristic of the relation between fire and socioeconomic factors.
Abstract: Fire differs remarkably from other natural disasters because of its close relationship with human behaviors, which are affected by socioeconomic factors. In this article, research on the relationship between socioeconomic factors and fire in China is presented. Correlation analysis shows that in China, socioeconomic factors have a notable influence on fire. But the degree of correlation between them is different from that in other countries. In China, tendency of fire incidence and serious fire situations occur with the development of economy, which is a distinctive characteristic of the relationship between fire and socioeconomic factors. The fire data from China sounds paradoxical between two periods under study and the research indicates that fire rate has a poor relationship with college education, while in developed countries they are revealed as negative correlation. Finally, we discuss how socioeconomic factors influence fire and some predictions made on the fire situation in China.
20 citations
TL;DR: In this article, the effects of the ground conditions; surface inclination, the ground temperature, and the surrounding airflow velocities, on the propagation velocity of the flame tip and on the thickness of the flammable gas layer are investigated.
Abstract: The propagation of a precursor flame tip through a layered flammable gas mixture along a fuel-soaked ground is studied experimentally under the effect of the surrounding airflow. The behavior of the precursor flame tip is investigated by the simultaneous measurement of the images of color Schlieren photograph and a visualized chemiluminescence zone due to the OH radical in the flame tip. The effects of the ground conditions; the surface inclination, the ground temperature, and the surrounding airflow velocities, on the propagation velocity of the flame tip and on the thickness of the flammable gas layer are investigated. The thickness and the length of the OH luminescence zone in the flame tip are of the order of 1 and 2-3 cm, respectively. The tip of the OH luminescence zone propagates in the velocity boundary layer of the airflow. When the ground temperature is not so high, even above the stoichiometric temperature of combustion of the liquid fuel, no propagation of flame tip occurs in the counter airfl...
19 citations
TL;DR: A methodology to quantify the error in model predictions and the associated uncertainties with a statistical analysis of multiple scenarios and can be used to adjust future model predictions in order to take the error into account explicitly.
Abstract: The error in smoke transport models have mainly been analyzed with qualitative approaches till date. The results make it difficult to perform a quantitative assessment of the model error in fire safety design applications. Even if a model has a substantial model error, it can be a very useful tool, as long as the designer is aware of the errors and the uncertainties in the predictions. This paper presents a methodology to quantify the error in model predictions and the associated uncertainties with a statistical analysis of multiple scenarios. The knowledge of the model error can then be used to adjust future model predictions in order to take the error into account explicitly. This is done with an adjustment model valid for predictions during the whole pre-flashover phase of the fire scenario and not just at a single point in time. The approach taken is based on a quantitative comparison of model predictions and experimental measurements from several fire scenarios which constitute a scenario configuration. The application of the method is presented in a subsequent paper, where the model error in temperature predictions by the two-zone model CFAST 2.0 is analyzed.
18 citations
TL;DR: In this paper, the flame-retardant (FR) mechanism resulting from an intumescent phenomenon of the FR formulation: polyurethane polymer/ammonium polyphosphate/triazine carbonific (PU/APP/Carbonific).
Abstract: In this work, we studied the flame-retardant (FR) mechanism resulting from an intumescent phenomenon of the FR formulation: polyurethane polymer/ammonium polyphosphate/triazine carbonific (PU/APP/Carbonific). The FR properties (LOI and cone calorimeter) of the system were strongly improved in comparison with the PU and PU/APP systems. Characterization of the FR mechanism of the system PU/APP/Carbonific was carried out using scanning electron microscopy (SEM), elemental analysis (ELA), Fourier transform infrared spectroscopy (FTIR), and magic-angle spinning nuclear magnetic resonance (MAS-NMR 13C) spectroscopy of the solid state. The study shows the formation of organic phosphocarbonaceous esters, aromatic materials, and triazine-containing chars, which participate in the improvement of the fire-retardant properties of the system.
TL;DR: In this article, the design criteria are not clearly demonstrated to be worked out through systematic full-scale tests, and the authors propose a new approach to evaluate the reliability of smoke exhaust systems.
Abstract: Mechanical smoke exhaust systems are usually required in big atria of the Far East. However, the design criteria are not clearly demonstrated to be worked out through systematic full-scale tests. T...
TL;DR: In this article, the results and findings of three previous research projects are combined with new research to estimate the overall influence of longitudinal ventilation on fire size and spread in tunnels, concluding that although it may greatly increase the heat release rate of a fire in a tunnel, increasing the ventilation velocity will tend to reduce the likelihood of the fire spreading to an adjacent vehicle, assuming no flame impingement.
Abstract: The results and findings of three previous research projects are combined with new research to estimate the overall influence of longitudinal ventilation on fire size and spread in tunnels. Each of the three previous projects is briefly described. Combining the results of these three projects, together with the knowledge of HGV fire behavior in an experimental test, enables the estimation of the maximum fire size of a fire in a tunnel and the conditions under which it might spread to an adjacent vehicle, for a given longitudinal ventilation velocity. These results have been combined into a single computer model. The results are presented and discussed. It is concluded that, although it may greatly increase the heat release rate of a fire in a tunnel, increasing the ventilation velocity will tend to reduce the likelihood of the fire spreading to an adjacent vehicle, assuming no flame impingement.
TL;DR: In this article, an experimental study on the ignition process of wood exposed to a variable heat flux has been carried out, where the time to ignition, temperature distribution, and mass loss are measured for two species of wood.
Abstract: The ignition of combustible materials is an important process in a fire incident. In this work, an experimental study on the ignition process of wood exposed to a variable heat flux has been carried out. Increasing heat flux is adopted and adjusted to simulate a practical fire environment. The time to ignition, temperature distribution, and mass loss are measured for two species of wood. Both, the increasing rate of incident heat flux and the properties of wood, especially density, obviously affect the results. A conduction model is developed to calculate the surface temperature. A compound ignition criterion is brought out for a variable heat flux.
TL;DR: In this article, the smoke propagation characteristics in transversely ventilated tunnels were examined as a function of fire size, fire location, and airflow rates of supply and exhaust, and the results suggest that the smoke propagating distance and/or the smoke filling may serve as good criteria for determining the transverse ventilation rate.
Abstract: In order to determine the key features of the fire safety design in transversely ventilated tunnels, the smoke propagation characteristics are examined as a function of fire size, fire location, and airflow rates of supply and exhaust. A 12-m long scale model of the Memorial tunnel, with a scale down ratio of cross section 1/20, is used. Fire sizes and ventilation rates in real tunnels are then deduced from the Froude similarity. In general, it is found that the smoke propagating distance increases with the fire size and decreases with the exhaust ventilation rate. When the fire location is off-centered, the propagating distance becomes substantially larger than that of the centered fire with the same size. A hazardous situation generated from an imbalance between the supply rate and the exhaust rate is also observed. The results suggest that the smoke propagating distance and/or the smoke filling may serve as good criteria for determining the transverse ventilation rate.
TL;DR: In this article, a modified smoke filling time calculation method with sprinkler effect is presented, where a full-scale experimental program is conducted to evaluate the feasibility of the applica- tion of the model.
Abstract: Recently, many computational methods for determining the position of a smoke layer height in a confined space have been reported for fire safety design purposes. Most of the existing smoke layer height prediction models were developed without considering the sprinkler effect. However, most buildings are required to install sprinkler systems under the local fire regulations in many countries. Hence, most of the smoke filling time calculation models were not able to reflect the smoke layer height in a real fire. A modified smoke filling time calculation method with sprinkler effect is presented in this paper. In addition to the theoretical analysis, a full-scale experimental program is conducted to evaluate the feasibility of the applica- tion of the model. The experimental results show that the smoke filling time of a sprinklered fire test may have a 10-20% faster smoke filling time than an unsprinklered fire test in a confined space. Besides, a new algorithm for applied light beam detectors is developed to measure the smoke layer height precisely, in this study.
TL;DR: In this article, the authors examined the architectural fire safety design of corridors as a component of emergency building evacuation from the perspective of a maximum escape distance by the occupant in order not to experience skin pain or skin burn from exposure to the thermal radiation of a hot smoke layer.
Abstract: The architectural fire safety design of corridors as a component of emergency building evacuation is examined from the perspective of a maximum escape distance by the occupant in order not to experience skin pain or skin burn from exposure to the thermal radiation of a hot smoke layer. In this work, empirical expressions have been proposed to approximate an evacuee to study the thermal hazard. The maximum escape distance is calculated from the exposure time limit of the evacuee and the thermal radiant heat flux falling upon the evacuee's head at some walking speeds. The range of the maximum escape distance and its dependence on corridor's parameters are determined for the typical width of a corridor, the smoke layer temperature and the smoke layer depth. The length of a corridor for safe escape can be determined as a function of the corridor's width, smoke layer depth and temperature, at the walking speeds of evacuees. The maximum escape distance can be used as a quantitative design criterion for the design of corridors and similar structures where a hot smoke layer is expected.
TL;DR: In this paper, the effects of zeolites 4A, 13X, mordenite, and ZSM-5 on the thermal degradation and charring of intumescent ammonium polyphosphate (APP) and PER systems were explored by X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analyses (TGA).
Abstract: The effects of zeolites 4A, 13X, mordenite, and ZSM-5 on the thermal degradation and charring of intumescent ammonium polyphosphate (APP)–pentaerythritol (PER) systems were explored by X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analyses (TGA). The weight loss rate of the third main degradation step (corresponding to the maximum degradation rate of APP–PER) was remarkably decreased for all systems with addition of zeolites, especially for the systems with 4A and 13X where the minimal weight loss rate, 0.13%/ C and 0.11%/ C, were found. The residues of APP–PER systems with 4A and 13X at 600 C were 33–35% higher than that of the pure APP–PER system. The XPS–TGA results indicated that zeolites might execute their effects on the thermal degradation of APP–PER by two ways, that is, by catalyzing the esterification reaction between APP and PER at temperatures below 250 C and enhancing the cross-linking and charring by SiO2 and Al2O3 produced by the breakage of zeolites at temperatures above 2...
TL;DR: In this article, a mixture of ammonium polyphosphate and 2-methyl-1,2- oxaphospholan-5-one 2-oxide exhibits a synergistic fire-retardant effect in high-impact polystyrene (HIPS), as measured by the oxygen index and UL94 vertical burning test.
Abstract: A mixture of ammonium polyphosphate and 2-methyl-1,2- oxaphospholan-5-one 2-oxide exhibits a synergistic fire-retardant effect in high-impact polystyrene (HIPS), as measured by the oxygen index and UL94 vertical burning test. Mechanistic studies carried out by means of TGA, FT-IR, and GC/MS revealed that the condensed-phase activity of the additives resulted in the formation of a polyphosphoric acid and probable polyphosphazene-type structures is likely to account for the flame retardation. In addition, reaction between the additives and polymer alters the composition of the pyrolysis products compared to those of neat HIPS.
TL;DR: In this article, the Setaflash closed-cup tester is used to measure the flash points of combustible liquids, especially for high-viscosity liquids, and good correlations can be found between the flash point and the time to ignition, the peak heat release rate, and the propensity to flashover.
Abstract: The closed-cup flash points of nine organic compounds and 38 organosilicon compounds are measured using a Setaflash closed-cup tester. This study demonstrates that Setaflash closed-cup tester is an effective tool for measuring the flash points of combustible liquids, especially for high-viscosity liquids. The flammability properties of these chemical compounds are determined using a cone calorimeter at a low-incident heat flux of 3 kW/m 2 . The results show that good correlations can be found between the closed-cup flash point and the time to ignition, the time to peak heat release rate, and the propensity to flashover. There is no good correlation between the closed-cup flash point and the peak heat release rate.
TL;DR: In this paper, the authors investigated the backdraft in underground mine tunnel fire by means of experimental simulation and found that a backdraft occurs with the reversal of descensionally ventilated airflow.
Abstract: The backdraft in an underground mine tunnel fire is investigated by means of experimental simulation. According to the results, such a backdraft phenomenon is different from a general one in a compartment fire. A backdraft of tunnel fire takes place in an open system with flowing gases and no newly formed vents are needed to result in it under such an occasion. The backdraft occurs with the reversal of descensionally ventilated airflow. The results obtained extend the range where a backdraft can occur and promote a better understanding of the backdraft phenomenon.
TL;DR: In this paper, the variation of CO produced by burning wood cribs is studied, and a series of experiments with different wood crib structures are conducted, and the mass loss rate and the concentration of CO are measured.
Abstract: Traditionally, the burning of wood cribs has been divided into a surface area controlled regime, and a porosity controlled regime according to mass loss rate. In the two regimes, the concentration of CO produced should also have different characteristics. In this paper, the variation of concentration of CO produced by burning wood cribs is studied. A series of experiments with different wood crib structures are conducted. The mass loss rate and the concentration of CO are measured. It has been found that the concentration of CO has an obvious transitional state, and the corresponding transitional value of porosity factor for dividing the two burning regimes according to the concentration of CO is exactly the same as that according to the mass loss rate.
TL;DR: The evaluation of the predictive capability of the smoke transport model CFAST 2.0 shows that the statistical method is applicable for this purpose and that reduction of the model error can be achieved with the adjustment model for the types of scenarios subject to analysis.
Abstract: In this paper the predictive capability of the smoke transport model CFAST 2.0 is evaluated for five different scenario configurations. The evaluation is made by statistical analysis according to a methodology presented in an earlier paper. Model predictions and experimental data, previously published, are compared and quantitative measures of the predictive capability are thus derived. With the quantitative knowledge of the model error, future predictions from the two-zone model can be adjusted so that the error is taken into account. The suitable method of adjustment depends on how the uncertainty is treated in a specific application. This can be done either by using conservative adjustments or by treating the uncertainty in the predictions as a stochastic variable. The evaluation shows that the statistical method is applicable for this purpose and that reduction of the model error can be achieved with the adjustment model for the types of scenarios subject to analysis.
TL;DR: In this article, the authors used a zone model as well as simplified mathematical models, which are commonly employed by fire safety engineering designers to investigate the smoke temperature and accompanying effect in an underground structure with a long corridor.
Abstract: In Taiwan, since underground structures are more functional and complicated than usual buildings, for example, mass rapid transportation centers and underground shopping streets, performance-based designs are always adopted in allowing architects greater design freedom without any reduction in levels of fire safety of underground structures. Consequently, the function and efficiency of the smoke control systems in a public-use underground structure are becoming one of the important subjects for fire safety design engineers. This paper used a zone model as well as simplified mathematical models, which are commonly employed by fire safety engineering designers to investigate the smoke temperature and accompanying effect in an underground structure with a long corridor. Also, an evacuation assessment and escape time calculation were evaluated in this paper to address the strong relationship between evacuation and smoke control design. Further, experimental data collected from a full-scale underground corridor in Japan was used to verify the results from the model predictions. Language: en
TL;DR: In this paper, a multicell concept, which first divides the total space into subspaces and then uses the traditional two-layer zone model in each subspace, is performed to simulate the smoke filling process in a domestic boarding-arrival passage, with an aspect ratio of about 52.3, of an international airport terminal by using CFAST version 4.0.
Abstract: A multicell concept, which first divides the total space into subspaces and then uses the traditional two-layer zone model in each subspace, is performed in this paper to simulate the smoke filling process in a domestic boarding-arrival passage, with an aspect ratio of about 52.3, of an international airport terminal by using CFAST version 4.0.2. Results show that the impingement of ceiling jet upon the passage ends is a critical time for the evacuation of people near these ends. Some comparisons are also presented to show that more reasonable results about the smoke temperature field and the smoke layer interface height are achieved using this method than using the traditional two-layer zone model. Further, results through different subspace dividing technology and using FDS version 3.0, a CFD model, are also achieved and compared on simulating the smoke filling process in a simplified passage, for the purpose of studying the prediction of impingement time, the smoke temperature distribution, and the smoke layer interface height development pattern before and after the impingement. The limitations of this modeling technology and future research topics are also discussed.
TL;DR: In this paper, it was argued that the halogens, as flame extinguishants, act as heat sinks in the same manner as nitrogen although they do not enter the combustion chemistry.
Abstract: In previous papers it was argued that the halogens, as flame extinguishants, act as heat sinks in the same manner as nitrogen although they do enter the combustion chemistry. Thus they act, as extinguishants, as heat sinks although, because of their fuel content, they may also add energy to the system.
TL;DR: Among fire experts, scientists and consultants, contributions to The Forum will not be refereed in the conventional sense, but will be subject to review by the Editor or a member of the Journal’s Editorial Board relative to appropriateness, clarity, timeliness, and scope of interest.
Abstract: among fire experts, scientists and consultants. Contributions to The Forum will not be refereed in the conventional sense, but will be subject to review by the Editor or a member of the Journal’s Editorial Board relative to appropriateness, clarity, timeliness, and scope of interest. The Editor will be the sole judge of those contributions to be published. Opinions expressed, however, are those of the authors and not of the Editor or Sage Publications Ltd.
TL;DR: Among fire experts, scientists and consultants, contributions to The Forum will not be refereed in the conventional sense, but will be subject to review by the Editor or a member of the Journal’s Editorial Board relative to appropriateness, clarity, timeliness, and scope of interest.
Abstract: among fire experts, scientists and consultants. Contributions to The Forum will not be refereed in the conventional sense, but will be subject to review by the Editor or a member of the Journal’s Editorial Board relative to appropriateness, clarity, timeliness, and scope of interest. The Editor will be the sole judge of those contributions to be published. Opinions expressed, however, are those of the authors and not of the Editor or Sage Publications Ltd.
TL;DR: Using semi-quantitative arguments based on the principles of stoichiometry and ignition, the behaviour of a flammable vapour in a microcalorimeter is analysed in this paper.
Abstract: Using semi-quantitative arguments based on the principles of stoichiometry and ignition limits the behaviour of a flammable vapour in a microcalorimeter is analysed. As acknowledged at the end of the paper, the author has also used input by an investigator other than himself in preparing a synthesis suitable for publication.