Showing papers in "Fire and Materials in 2011"
TL;DR: In this article, a cone calorimeter was used to determine the burning behavior of polyester fabrics with varying densities, and the effects of these variables on TTI and pkHRR were observed.
Abstract: The aim of this study was the optimization of cone calorimeter to determine the burning behavior of textile fabrics. In particular, the combustion behavior of commercial polyester textile fabrics with varying densities was studied in terms of time to ignition (TTI), heat release rate (HRR), and relative peak (pkHRR) were monitored. Reproducibility and repeatability of the data have been verified by the influence of instrument variable including incident heat flux, the temperature of ceramic backing pads and retaining grid used during sample mounting as well as sample weight (as the number of fabric layers), the density of textiles, and the relative humidity. A low reproducibility has been obtained when a wire grid was not used to stabilize samples during the tests. The effects of these variables on TTI and pkHRR were observed. Copyright © 2010 John Wiley & Sons, Ltd.
106 citations
TL;DR: In this article, material properties and external factors influencing the charring rate of solid wood and glue-laminated timber were investigated for both solid and gluelaminated timbers, respectively.
Abstract: Material properties and external factors influencing the charring rate of solid wood and glue-laminated timber
73 citations
TL;DR: In this article, failure modes for a variety of parallel and series arc faults are described along with circuit breaker response, electrical data, photos, and video frames to explain the conditions that led to a hazardous condition.
Abstract: While there are many circumstances that can lead to residential electrical fires, it is useful and practical to identify and document potential hazardous conditions and provide physical explanations of electrically initiated fires. Failure modes for a variety of parallel and series arc faults are described along with circuit breaker response, electrical data, photos, and video frames to explain the conditions that led to a hazardous condition. This work identifies some of the various conditions that can create overheated hazardous conditions and shows how wire insulation is commonly the first to ignite. Conditions explored include bundled extension cords under rugs, abused NM-B at a load center entrance, broken wires and loose connections. Physical phenomena investigated include glowing connections, series and parallel arcing faults. Low and high current arc energies are discussed and compared to the combustible energy of volatile gases produced from wire insulation to illustrate the wide difference in the arc energy compared to chemical combustion energy from the decomposed PVC. Electrical wire insulation properties were also measured on various wire types to show the effects of thermal aging. Hardness of the wire insulation and cracking of the insulation was used as a measure of insulation lifetime at 140∘C. Copyright © 2010 John Wiley & Sons, Ltd.
61 citations
TL;DR: In this article, the spectral absorptivity of 62 products has been measured in the wavelength region of 0.3-20 mu m and the effective absorptivities for fire-induced heat radiation typically lie in the range of0.75-0.95.
Abstract: The spectral absorptivity of 62 products has been measured in the wavelength region of 0.3-20 mu m. Effective absorptivity for fire-induced heat radiation typically lies in the range of 0.75-0.95. It was found that the effective absorptivity varies significantly with the temperature of the heat source. This has implications on the heating of a surface. The effect is more important when the absorptivity is used as input for calculations of ignition temperature and thermal inertia. It was also found that the absorptivity of radiation from fires for products exposed to irradiation in many cases decreased with increased exposure time. This is surprising since, for example, wood that is darkened when exposed to heat obviously has a higher absorptivity in the visual part of the spectrum than fresh non-darkened wood. The reason that was identified for this is because the absorptivity in the IR drops, and measurement results are given which clearly illustrate this.
57 citations
TL;DR: In this article, a new kind of dry powder based on potassium bicarbonate was studied for fire suppression, which was denoted as "K-powder" and used in laboratory-scale experiments.
Abstract: Fire suppression effectiveness of a new kind of dry powder based on potassium bicarbonate was studied in this paper. The powder consisted of superfine potassium bicarbonate and some organic and inorganic additives, which was denoted as ‘K-powder’. The physical and chemical characteristics of the K-powder were characterized by a series of techniques of X-ray diffraction, scanning electron microscopy, Fourier transforms infrared (FTIR) and thermal gravity analysis, etc. Performance of the new potassium-based powder in fire suppression was studied by laboratory-scale experiments, which exhibited much superior fire suppression efficacy than that of the commercial bicarbonate powder. Such improvements could be reasonably ascribed to the special chemical composition, microstructure and radiation effect on the mechanisms. The preparation, fire suppression and possible fire-extinguishing mechanisms were studied in detail. Copyright © 2010 John Wiley & Sons, Ltd.
52 citations
TL;DR: In this paper, the influence of the dehydration temperature and the initial water/cement ratio on the rehydration activity of dehydrated cement paste (DCP) was presented.
Abstract: Subjected to the wet surrounding, hydrated cement paste (HCP) exposed to high temperature may exhibit rehydration behavior. This paper presents the influence of the dehydration temperature and the initial water/cement ratio on the rehydration activity of dehydrated cement paste (DCP). Original HCPs were prepared with two water/cement ratios of 0.3 and 0.5, respectively, and cured under the fog-spraying standard condition for 30thinspacedays. The DCP powders used were obtained by grinding dry HCP less than 75µm and then subjecting to different temperatures, up to 900∘C. The rehydration properties of DCP were evaluated by the required water for standard consistency, the setting time, the rehydrated compressive strength and the microstructure evolution. X-ray diffraction (XRD) was employed to identify the crystalline phases before and after rehydration. Experimental results showed that the coupled rehydration effect from the dehydrated hydration products and the initially unhydrated cement determined the rehydration behavior of DCP. The rehydration of DCP strongly depended on the dehydration temperature and the water/cement ratio of the original HCP. Copyright © 2010 John Wiley & Sons, Ltd.
47 citations
TL;DR: In this paper, the mass loss rate (MLR) of poly(methyl methacrylate) (PMMA) exposed to known radiant fluxes is simulated with two recently developed numerical codes, the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) and the Federal Aviation Administration (FAA) ThermaKin.
Abstract: The mass loss rate (MLR) of poly(methyl methacrylate) (PMMA) exposed to known radiant fluxes is simulated with two recently developed numerical codes, the National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS) and the Federal Aviation Administration (FAA) ThermaKin. The influence of various material properties (thickness, thermal conductivity, specific heat, absorption of infrared radiation, heat of reaction) on mass loss history is assessed, via their effect on the ignition time, average MLR, peak MLR, and time to peak. The two codes predict the influence of material parameters on the MLR in the order of decreasing importance: heat of reaction, thickness, specific heat, absorption coefficient, thermal conductivity, and activation energy of the polymer decomposition. Changes in the material properties also influence the MLR curves by switching the sample from thermally thick to thermally thin. The two numerical codes are generally in very good agreement for their predictions of the MLR vs time curves, except when in-depth absorption of radiation was important. Copyright © 2010 John Wiley & Sons, Ltd.
40 citations
TL;DR: In this article, the effect of combination of expandable graphite (EG) with nanoclays would be exploited with sodium and organo-modified montmorillonites, namely Cloisite®Na, Cloisitic®10A and Cloisites®30B.
Abstract: Expandable graphite (EG) and polyethylene terephthalate (PET) were melt blended to develop a new nanocomposite intumescent flame retardant in which the effect of combination of EG with nanoclays would be exploited with sodium and organo-modified montmorillonites, namely Cloisite®Na, Cloisite®10A and Cloisite®30B. X-ray diffraction analysis coupled to transmission electron microscopy and rheology shows that PET–EG–clay compounds are characterized by an exfoliated and/or intercalated morphology as a function of the type of clay. Thermal stability of composites is enhanced in nitrogen and air by filler adding as compared with neat PET, while combustion rate is decreased both in the bulk material and in textiles made of fibers spun from the compound. Copyright © 2010 John Wiley & Sons, Ltd.
40 citations
TL;DR: In this paper, mesoporous silica SBA-15 synthesized from Pluronic P123 and tetraethoxysilane was used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame-retardant (IFR) system.
Abstract: Mesoporous silica SBA-15 synthesized from Pluronic P123 and tetraethoxysilane was used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame-retardant (IFR) system. Limiting oxygen index (LOI), UL-94 rating and thermogravimetric analysis were used to evaluate the synergistic effect of SBA-15 on PP/IFR system. It showed that PP/IFR system could reach V-0 with loading of SBA-15 ranging from 0.5 to 3 wt%, while without SBA-15 it had no rating at UL-94 test. The LOI value increased from 25.5 to 32.2 when the loading of SBA-15 was 1 wt%. The thermal stability of PP/IFR was improved in the presence of SBA-15 and the amount of the char residue at 600 degrees C was increased from 8.96 to 16.42 wt% when loading of SBA-15 varied from 0.5 to 5 wt%. Laser Raman spectroscopy (LRS) and scanning electron microscopy were employed to study the morphology of the char residue of PP/IFR system with and without SBA-15. Copyright (C) 2010 John Wiley & Sons, Ltd.
33 citations
TL;DR: In this paper, the synergistic effect on the thermal decomposition and heat release rate (HRR) of unsaturated polyester (UP) resin blended with multiwalled carbon nanotubes (MWNTs) and sepiolite nanoclay was investigated using thermal gravimetric analysis (TGA), pyrolysis combustion flow calorimetery (PCFC), and the cone calorimeter.
Abstract: The synergistic effect on the thermal decomposition and heat release rate (HRR) in particular the peak heat release rate (PHRR) of unsaturated polyester (UP) resin blended with multiwalled carbon nanotubes (MWNTs) and sepiolite nanoclay was investigated using thermal gravimetric analysis (TGA), pyrolysis combustion flow calorimetery (PCFC) and the cone calorimetery. Initial microcalorimeter findings established a synergistic effect for ternary system comprising a 10:0.5 wt% mixture of sepiolite:MWNT, respectively, which resulted in a 40% reduction in heat release capacity (HRC). This result was also confirmed within the well-established cone calorimeter by a 50% reduction in PHRR in contrast to unfilled UP. The mechanism behind this reduction is thought to be due to the bridging of the MWNTs between the sepiolite clay needles, creating a tight protective surface layer that reduces the MLR. TGA also confirmed the advantage of such a ternary system through a 36∘C shift in the onset decomposition temperature and an 11% increase in residual char. Copyright © 2010 John Wiley & Sons, Ltd.
32 citations
TL;DR: In this paper, the simultaneous use of conventional fire-retardant additives and an insulative intumescent thermal barrier/mat was investigated to improve the fire performance and mechanical property retention of glass-fibre-reinforced polyester composites.
Abstract: This study investigates the simultaneous use of conventional fire-retardant additives and an insulative intumescent thermal barrier/mat to improve the fire performance and mechanical property retention of glass-fibre-reinforced polyester (GRP) composites. Significant reductions in the peak heat release rate (PHRR) and total heat release (THR) were observed from measured cone calorimetric data following the addition of nitrogen, phosphorous, halogen containing and hydroxylated fire-retardant additives. Some fire-retarded glass-fibre-reinforced composites further protected by an intumescent mat containing silicate fibres, expandable graphite and borosilicate glass bound together by an organic matrix show further reductions in PHRR. Despite improving the fire retardancy of the composites, the presence of fire-retardant additives alone does not improve flexural modulus retention following exposure to a heat source. However, the introduction of a 'passive' fire proofing insulative fabric enhances fire performance while preserving the mechanical properties of composites exposed to high heat fluxes or fires.
TL;DR: In this paper, temperature response and mass loss data were determined using a high heat flux decomposition apparatus with controlled oxygen environment, including thermal conductivity, specific heat capacity and density as a function of temperature as well as heat of decomposition and Arrhenius kinetic decomposition constants.
Abstract: Thermal properties were measured on coupon size samples for use in predicting the temperature response and mass transfer during fires exposures. The thermal properties were determined up to temperatures of 800°C through inverse heat transfer analysis on temperature response and mass loss data. Temperature response and mass loss data were determined using a high heat flux decomposition apparatus with controlled oxygen environment. Data included thermal conductivity, specific heat capacity, and density as a function of temperature as well as heat of decomposition and Arrhenius kinetic decomposition constants. Properties for inert materials (no decomposition) compared well with manufacturer reported values and values using other methods. Properties for two decomposing materials, woven glass vinyl ester composite and balsa wood, were measured and compared well with data from other methods. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, the thermal radiation protection performance of aluminized fabrics made of basalt fiber and glass fiber was evaluated and compared using the UV-Vis-NIR (ultraviolet-visible-near infrared) spectrophotometer.
Abstract: Rapid progress has been made in the field of fire protection during the past few decades, nevertheless, the development of fire protective clothing with prolonged durability has always been a matter for public attention. In order to prevent or minimize skin burn damage resulting from flashover, a kind of thermal protective composite fabric, the surface of which is aluminized, has been upgraded and developed. Using the UV–Vis–NIR (ultraviolet–visible–near infrared) spectrophotometer, the thermal radiation protective performance of aluminized fabrics made of basalt fiber and glass fiber were evaluated and compared. The aluminized fabrics and the substrate fabrics used were exposed to a fire environment generated by burning liquified gas for a few minutes, aiming at evaluating the protective effect of the aluminum coating and characterizing the thermal insulating performance. The results showed that the spectral reflectance of aluminized fabrics present obvious differences over a wide range of wavelengths, perhaps due to the different yarn parameters and weave structure. The fire exposure experiment indicated that the aluminized fabric of basalt fiber had better thermal protective performance than the substrate fabrics. Although the thermal insulating performance of aluminized fabrics is insufficient to provide enough time for people to focus on his/her job, the aluminized fabrics exhibit great potential application in the fields of firefighting and military. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, a fracture energy-based failure criterion (GC) is used to characterize the adhesion between spray-applied fire-resistant materials and steel structures, and the theoretical basis of this test method is validated by experimental compliance tests.
Abstract: Adhesion of spray-applied fire-resistive materials (SFRMs) to steel structures is critical in enabling a building to remain functional during a fire for a specific period of time for life safety and fire department access. Empirical tests such as ASTM E736 have been widely adopted by the industry in an effort to ensure sufficient bonding between SFRMs and steel structures. ASTM E736 assesses the adhesion of SFRMs by using tensile strength, a failure parameter that depends on the test geometry and has limited use for predicting failure in other geometries and conditions. These limitations have produced an urgent need for a scientifically based adhesion test method. In this paper, we propose a new test method that would provide more fundamental information that is independent of test geometry and has predictive capability. This paper utilizes a fracture energy-based failure criterion (GC) to characterize the adhesion between SFRMs and steel. The theoretical basis of this test method is validated by experimental compliance tests. The dependence of GC on various test variables such as specimen width, substrate type, SFRM formulation, and test rate are examined. A comparison between this new test method, and the current widely used strength-based test method is also presented. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In the last half century, the science of understanding how fires burn and how heat smoke and gases are generated and how they affect people has progressed substantially in the last 50 years as mentioned in this paper and the principles of facility design for life safety in fires have reached a degree of maturity.
Abstract: The science of understanding how fires burn and how heat smoke and gases are generated and affect people has progressed substantially in the last half century. The principles of facility design for life safety in fires have reached a degree of maturity. Standards and code provisions for fire detection, suppression and control have become the norm. Real-scale (or nearly real-scale) test methods for the flammability of furnishings and interior finish have been established. In addition, some tests have been developed that measure the results of the burning of a small sample from the finished product. Yet, while there have been numerous small-scale apparatuses developed for assessing the generation of heat, toxic gases, and visible or corrosive smoke, these facets of life and property safety have not found widespread inclusion in building and fire codes. There has been an invigorated effort in ISO TC92 SC3, Fire Threat to People and the Environment, to develop a coherent and comprehensive set of fire safety standards and guidance documents for life safety. Smaller efforts are ongoing within some national and regional standards bodies. In November 2008, experts in this field gathered at The Royal Society in London to hear papers that captured the state of the art and to discuss where we might go from here. This paper summarizes the papers and the discussion from that meeting. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, five commodity thermoplastics (polyethylene, polypropylene, thermoplastic polyurethane, poly(butylene terephthalate), and poly(amide 6)) were melt compounded with vapor grown carbon nanofibers via twin screw extrusion.
Abstract: Five commodity thermoplastics (polyethylene, polypropylene, thermoplastic polyurethane, poly(butylene terephthalate), and poly(amide 6)) were melt compounded with vapor grown carbon nanofibers via twin screw extrusion. These materials were then analyzed for flammability behavior by cone calorimeter to determine how the nanofibers would reduce flammability of the polymers. It was found by cone calorimeter that the nanofibers greatly reduced peak heat release rate and improved many other flammability parameters of the samples. However, smoke release was increased in all samples, which may be one drawback of using these materials. Interestingly, the amount of flammability reduction was not uniform across all samples, with nanofiber reducing flammability the most in the thermoplastic polyurethane sample. The mechanism of flammability reduction in the polymers tested in this paper is shown again to be a mass loss rate reduction induced by the formation of thick tangled networks of carbon nanofibers during polymer decomposition. This mechanism was confirmed by studying the mass loss rate curves and electron microscopy analysis of the final chars collected from the cone calorimeter experiments. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, two new methods are presented, one that uses the vapor pressure, and one based on the normal boiling point and enthalpy of vaporization at the same boiling point.
Abstract: Published flash point prediction methods are evaluated for accuracy against experimental data from the DIPPR ® 801 database. The most accurate methods require a vapor pressure correlation, which is often not available. Two new methods are presented, one that uses the vapor pressure, and one based on the normal boiling point and enthalpy of vaporization at the normal boiling point. The vapor pressure method shows little improvement over the previous methods unless group contributions are implemented. The boiling point method predicts the flash point within an absolute average deviation of 1.3% when compared with data for more than 1000 compounds. The previous most accurate method that was not based on vapor pressure exhibited an absolute average deviation of 1.84% for the same test set. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors describe the results from an experimental campaign, focused on vertical upward flame spread over a charring material, and derive the temporal evolution of the mass loss rate due to pyrolysis.
Abstract: In this paper, we describe the results from an experimental campaign, focused on vertical upward flame spread over a charring material. First, for validation purposes of simulation tools, we report on cone calorimeter results for square (9.8 cm x 9.8 cm), 1.65 cm thick, medium density fibre samples, mounted horizontally. Temperature is shown at the surface and at different depths. The mass of the sample is continuously measured. From the raw data, we derive the temporal evolution of the mass loss rate due to pyrolysis. Different externally imposed heat fluxes are investigated (20, 30 and 50 kW/m(2)), onto dry and wet material. Afterwards, for the configuration of two particle board plates (0.025 m thick, 0.4 m wide and 2.5 m high), vertically mounted face to face is considered. Two different horizontal spacing distances between the two plates are studied (30.5 and 10.5 cm). The purpose of this set-up is to investigate the vertical upward flame spread with strong radiative heat feedback. To that purpose, the temporal evolution of surface temperature is measured over the height of the plates. The measurement data are used to test a pyrolysis model in numerical simulations. Copyright (C) 2010 John Wiley & Sons, Ltd.
TL;DR: The effects of Na2WO4, Na2SnO3, and Na2MoO4 on the thermal decomposition and fire performance of wood were characterized by thermogravimetric analysis, differential thermOGravimetry, differential thermal analysis, and thermodynamic mass spectrometry analysis as discussed by the authors.
Abstract: The effects of Na2WO4, Na2SnO3, and Na2MoO4 on the thermal decomposition and fire performance of wood were characterized by thermogravimetric analysis, differential thermogravimetry, differential thermal analysis, and thermogravimetry–mass spectrometry analysis. The kinetics of thermal degradation were analyzed using Doyle's equation and the limiting oxygen index was shown to be enhanced by the addition of Na2WO4, Na2SnO3, and Na2MoO4. The addition of these chemicals caused a decrease in the decomposition temperature, a reduction in weight, and an increase in the amount of char produced. The activation energies of the samples were also decreased after treatment by these flame retardants, during both the charring stage and the calcining stage. The flame retardants were shown to be able to catalyze the dehydration reaction, resulting in the formation of more H2O, CO2, and char molecules, but less levoglucosan and levoglucose. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, the effects of cooling regimes and post-fire-air-curing on compressive strength of mortar were investigated, and the results showed significant strength gain approximately 39, 100 and 130% for 400, 600, 800 and 1000°C elevated temperature, respectively.
Abstract: The effects of cooling regimes and post-fire-air-curing on compressive strength of mortar were investigated. Mortars were made with CEN reference sand, CEM I 42.5 R cement and natural spring water. The sand–cement and water–cement materials' ratios were chosen as 3.0 and 0.50 for all mixtures, respectively. At 28 days, the specimens were heated to maximum temperatures of 400, 600, 800 and 1000°C. Specimens were then allowed to cool in the air, furnace and water. After cooling, the specimens were air-recured. Compressive strength test was carried out before air-recuring and after 7 days of air-recuring. The highest reduction in compressive strength was observed at 1000°C regardless of cooling regime. Gradual cooling regime in air and furnace without post curing showed almost no difference in terms of compressive strength reduction for four elevated temperatures. Shock cooling in water caused significant reduction in compressive strength compared with both gradual cooling regimes without post curing. After air and furnace cooling regimes, 7 days air-recured specimens showed further reduction in compressive strength for four elevated temperatures. Specimens cooled in water and subjected to 7 days air-recuring showed significant strength gain approximately 39, 100 and 130% for 400, 600 and 800°C elevated temperature, respectively. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors developed a radiative fire spread submodel for which a suitable ignition criterion method is needed and implemented it into the fire zone modeling software BRANZFIRE, by converting it from a deterministic to a probabilistic model.
Abstract: Research is ongoing to increase the functionality of the fire zone modeling software BRANZFIRE, by converting it from a deterministic to a probabilistic model. One component of this work is the development of a radiative fire spread submodel for which a suitable ignition criterion method is needed. This paper provides details of that ignition criterion procedure and its implementation into the submodel.
A list of requirements that the ignition methodology had to satisfy was established. Of the many different piloted ignition models available, the Flux–Time Product technique, and its associated ignition criterion, was selected to be incorporated into the fire spread submodel. This method provides a practical engineering approximation of when a secondary fuel item that is subjected to incident radiation will ignite that is commensurate with the accuracy of the overall model.
Primarily to demonstrate the use of the technique in the submodel, a series of ignition experiments were conducted on a single example of upholstered furniture using the Cone Calorimeter apparatus, with specimens tested in both the horizontal and vertical orientation, under piloted and auto ignition conditions. The experimental incident radiation and time-to-ignition data, for the piloted ignition mode, was analyzed using a modified Flux–Time Product correlation procedure.
To deal with the auto ignition mode, an empirical approximation, based on the modified Flux–Time Product procedure, is proposed. Data for use in the submodel was therefore also derived for the auto ignition mode, based on an experimental determination of the minimum ignition flux. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, an enthalpy-based pyrolysis model is used to simulate vertically upward flame spread over a charring material in a parallel plate configuration, where the mass loss rate is also considered.
Abstract: Simulation results, obtained by means of application of an enthalpy-based pyrolysis model, are presented. The ultimate focus concerns the potential of the model to be used in flame spread simulations. As an example we discuss vertically upward flame spread over a charring material in a parallel plate configuration. First, the quality of the pyrolysis model is illustrated by means of cone calorimeter results for square (9.8 cm × 9.8 cm exposed area), 1.65 cm thick, horizontally mounted MDF samples. Temperatures are compared at the front surface and inside the material, for different externally imposed heat fluxes (20, 30 and 50 kW/m2), for dry and wet samples. The mass loss rate is also considered. Afterwards, vertically upward flame spread results are reported for large particle board plates (0.025 m thick, 0.4 m wide and 2.5 m high), vertically mounted face-to-face, for different horizontal spacings between the two plates. The simulation results are compared to experimental data, indicating that, provided that a correct flame height and corresponding heat flux are applied as boundary conditions, flame spread can be predicted accordingly, using the present pyrolysis model. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, the use of boehmite as a fire retardant in low-density polyethylene and polyamide 6 was explored by using X-ray diffraction and scanning electron microscopy.
Abstract: SUMMARY This paper explores the use of boehmite as a fire retardant in low-density polyethylene and polyamide 6. The structure and morphology of the filler are characterized by X-ray diffraction and scanning electron microscopy. The water content of our boehmite is estimated about 30% by thermogravimetric analysis. The filler/matrix interactions in nanocomposites are investigated by means of thermo-physical measurements: differential scanning calorimeter and thermogravimetry. The resulting morphology shows particles individually dispersed in the matrix. The fire tests present a fire-resistance effect at low filler content despite a different behavior as a function of the matrix. For instance, with only 2% volume of boehmite, the burning time of LDPE composite is significantly increased by 15%. At the same filler content in PA6, the burning time is solely increased by 4.5%. On the other hand, the limiting oxygen index is increased by +7.0% (only 2.6% with LDPE composites). Copyright 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, a simplified calculation method was proposed to evaluate the temperature of steel columns embedded in walls, based on numerical simulations and fire resistance tests, and it was observed that thicker walls or H steel columns with the web perpendicular to the wall surface provide greater thermal gradients in the cross-sections.
Abstract: Steel elements behave differently in fire case when isolated or embedded in building walls. The walls on one hand have a favorable effect protecting the elements from the excessive heating resulting from the fire and on the other hand they have a detrimental effect due to the thermal gradients originated in the elements cross-section. The simplified calculation methods proposed in EN 1993-1-2 for fire design do not take into account the case of steel elements embedded in walls, stipulating only a formulation for the assessment of the resistance for uniform temperature distribution. This paper presents a proposal of a new simplified calculation method to evaluate the temperature of steel columns embedded in walls. The method is based on numerical simulations and fire resistance tests. Steel columns totally or partially embedded in walls, with the web perpendicular or parallel to the wall surface, were tested.
In the study it was also observed that thicker walls or H steel columns with the web perpendicular to the wall surface provide greater thermal gradients in the cross-sections. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, a comprehensive set of experiments was carried out to investigate the spread of flames over porous sand beds wetted with finite quantities of propenol, and the key characteristics of flame propagation over porous beds when a limited supply of liquid fuel to the flame zone was available.
Abstract: A comprehensive set of experiments was carried out to investigate the spread of flames over porous sand beds wetted with finite quantities of propenol The aim was to examine the key characteristics of flame propagation over porous beds when a limited supply of liquid fuel to the flame zone was available Experiments were conducted over beds with depths ranging from 133 to 399 mm and average particle diameters between 05 and 5 mm under quiescent, assisted and opposed airflow configurations It was found that the flame spread rate for both assisted and opposed airflow configurations dramatically decreased as the air speed was increased although the extent of decay in the flame spread rate was more pronounced in the case of the opposed airflow configuration The experimental observations were explained by correlating the flame spread rate with the Damkohler number and fuel consumption flux The practical implications of the findings are briefly discussed in this paper Copyright © 2010 John Wiley & Sons, Ltd
TL;DR: In this paper, a lightweight composite with aluminosilicate binder and heat-resistant aggregate mixture of expanded vermiculite and electrical porcelain is measured in a wide temperature range.
Abstract: Thermal diffusivity, specific heat capacity and linear thermal expansion coefficient of a lightweight composite with alkali-activated aluminosilicate binder and heat-resistant aggregate mixture of expanded vermiculite and electrical porcelain are measured in a wide temperature range. Experimental results show that the studied material has good prerequisites for high-temperature applications. The apparent thermal diffusivity at one-sided heating is significantly lower than at room temperature, and decreases for temperatures higher than 400∘C. The effective specific heat capacity at elevated temperatures increases with temperature in almost the whole analyzed temperature range. The linear thermal expansion coefficient is substantially lower compared with common cement-based composites. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, based on analyzing the approximate heat balance on the control volume similar to that in the MQH method, a dimensional relationship was derived that facilitates the estimation of pre-flashover temperatures, which is used in the popular guidance literature as the key parameters for practical methods of predicting flashover.
Abstract: Among those factors that affect the likelihood of flashover in enclosure fires, the thermal inertia of lining materials, ventilation factor of door openings, heat release rate of fuel, and internal dimensions of the enclosure are the most important. The effects of the four factors are related, so it is very necessary to study their combined effects. In the present study, based on analyzing the approximate heat balance on the control volume similar to that in the MQH method, a dimensional relationship was derived that facilitates the estimation of pre-flashover temperatures, which is used in the popular guidance literature as the key parameters for practical methods of predicting flashover. By correlating a vast amount of data gained in both small-scale and large-scale enclosure fire experiments, an important equation was obtained, which can embody explicitly and quantitatively the combined effects of the four important factors on the likelihood of flashover. According to the temperature criteria of 600°C identifying flashover, a new ‘combined method of predicting flashover’ was put forward. The validity of the method was verified in small-scale experiments, and the results showed that it could be applied to predict well whether flashover occurs in enclosure fires or not. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, mid-infrared polarization spectroscopy is used for in situ measurements of toxic gases in smoke-laden environments, which can be used for monitoring toxic gases.
Abstract: Mid-infrared polarization spectroscopy : A tool for in situ measurements of toxic gases in smoke-laden environments
TL;DR: In this article, the critical breakage stress of 6, 8, 10, 10 and 12 mm float glass was measured under the condition of a room temperature and a hot environment (200°C).
Abstract: The objective of this study is to directly measure the critical breakage stress for glass through mechanical tensile experiments based on MTS 810 apparatus. Two series of experiments were, respectively, conducted under the condition with a room temperature (25°C) and a hot environment (200°C) for float glass. The results show that the critical breakage stresses of 6, 8, 10 and 12 mm float glass are, respectively, 74, 127, 158 and 198% larger than that of 4 mm float glass under the condition with a room temperature (25°C). Similarly, the critical breakage stresses of 6, 10 and 12 mm float glass are, respectively, 29, 72 and 93% larger than 4 mm glass in the hot environment (200°C). In addition, through the comparison between the two series of experiments, it suggests that the critical breakage stresses of 6, 8, 10 and 12 mm thick float glass in a hot environment are, respectively, 7, 48, 16 and 19% smaller than that in a room temperature. It is suggested that the measured critical breakage stress of float glass here is relatively smaller than those in the previous measurements. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, a fire in a five-storey apartment building was investigated experimentally and numerically and the room of origin was a living room in the second floor and the fire was started by a candle on a television set.
Abstract: A fire in a five-storey apartment building was investigated experimentally and numerically. The room of origin of the fire was a living room in the second floor and the fire was started by a candle on a television set. The fire spread externally over the building faccade and internally along the staircase and affected all the flats above leading to two fatalities. It is estimated that the fire was discovered minutes after ignition and the fire service was called very shortly after the detection and was at the scene 9 min after the call. By this time large sections of the facade were on fire already. The rapid fire that spread over the facade and the staircase necessitated detailed investigations. Compliance of building products with the building regulations was investigated. One conclusion of the investigations was that the person who caused the fire by leaving the candle on the TV set unattended should not be held responsible for the two fatalities in the upper floors. Copyright © 2010 John Wiley & Sons, Ltd.