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Fire and Materials

Wiley Online Library : Fire and Materials

Published: 2018-03-01T00:00:00-05:00


Residual cube strength of coarse RCA concrete after exposure to elevated temperatures


An experimental investigation was carried on the residual cube strength of concrete made with coarse recycled concrete aggregate (RCA) after exposure to temperatures of 20°C to 800°C. A total of 360 cube specimens were made with 2 water/cement ratios (w/c = 0.31 and 0.45) and 5 replacement percentages (r = 0%, 25%, 50%, 75%, and 100%) of coarse RCA. Effects of different cooling regimes (natural cooling, water cooling) on the residual compressive strength of coarse RCA concrete after exposure were also investigated. Experimental results show that the cube compressive strength and splitting tensile strength of coarse RCA concrete diminish with increasing temperature, of which the splitting tensile strength declines quicker than the compressive strength. The effects of coarse RCA replacement percentage and w/c ratio on losses in relative strength after being exposed to high temperatures are found to be insignificant. The results also reveal that the relative compressive strength of coarse RCA concrete cooled in water after heating process is lower than that of specimens cooled naturally.

Fire safety of thermoplastic polyurethane based on pyromellitic dianhydride


In this paper, pyromellitic dianhydride (PMDA) was firstly used as fire safety agent for thermoplastic polyurethane (TPU). And, the fire safety improvement of PMDA in TPU was intensively investigated by limiting oxygen index (LOI), smoke density test (SDT), cone calorimeter test, and thermogravimetric/infrared spectroscopy, respectively. It has been found that PMDA could significantly improve the ignition level, and the LOI value increase to 28.5% when 8.0 wt% PMDA was incorporated into TPU; PMDA also could effectively suppress the smoke production and heat release during the combustion process. The peak heat release rate and total smoke release of the sample with 8.0 wt% PMDA were decreased by 68% and 22% compared with pure TPU in cone calorimeter test. The thermogravimetric/infrared spectroscopy results showed that PMDA could improve the thermal stability of TPU composites at high temperature and increased the release of CO2, H2O, and so on. All results confirmed that PMDA would have a good prospect in reducing the fire hazard of TPU.

Effects of natural weathering on the fire properties of intumescent fire-retardant coatings


Fire-retardant coatings could be one option for providing enhanced protection to buildings during a wildfire, particularly when applied to combustible siding and in under-eave areas. Limited studies have been conducted on their effectiveness but maintaining adequate performance after weathering has been questioned. This paper reports on a study evaluating the effect of natural weathering on the performance of intumescent-type fire-retardant coatings. The main concerns were (a) the reduction of ignition resistance of the coating after weathering and (b) the coating might contribute as a combustible fuel and assist the fire growth after weathering. This study evaluated the performance of 3 intumescent coatings that were exposed to natural weathering conditions for up to 12 months. A bench-scale evaluation using a cone calorimeter was used to evaluate the performance of the coatings at 3 heat flux levels (30, 50, and 70 kW/m2). Our results showed that weathering exposure reduced the effectiveness of fire protection of intumescent coatings, but the weathered coatings did not act as additional fuels. Weathering orientation showed much less effect on the performance of intumescent coatings in comparison to other parameters. There was statistical evidence that weathering duration, heat flux level, and coating type affected the combustion properties.

Intrinsic flame resistance of polyurethane flexible foams: Unexpectedly low flammability without any flame retardant


Virgin polyurethane flexible foams are widely assumed to be highly flammable materials. The flammability of three model polyurethane flexible foams suggests that this may not be universally true. Two of them show unexpectedly low flammability in the limiting oxygen index test and pass flammability tests such as FMVSS 302 and FAR 25.853. Cone calorimetric measurements at 25 kW/m2 and 50 kW/m2 furthermore show a high resistance against ignition and demonstrate the self-extinguishing properties of these two virgin, flame-retardant-free, polyurethane flexible foams.

Modelling of heat release rate in upholstered furniture fire


Many fatal residential fires started from burning upholstered furniture, and so upholstered furniture fire has been studied rather extensively in developed countries. As many upholstered furniture were made in China, the hidden fire risk should be studied more. In this paper, full-scale experiments on the burning of upholstered furniture manufactured in China were conducted and analyzed. The oxygen consumption method was used to measure the heat release rate in a room calorimeter. An ignition source of a 20-kW gasoline pool fire of 0.2-m diameter was used to test square foam cushions and 4-seater sofas. A model of heat release rate predicting upholstered furniture fire in a room was developed on the basis of earlier Swedish works. Results were then used to justify the application of the Combustion Behaviour of Upholstered Furniture model to predict the heat release rate of furniture manufactured in China. The numerical values of key parameters in the model were determined. It is proposed to build up a database that can be used to model heat release rates upon burning furniture. Detailed procedures are illustrated in this paper.

Experimental study of the combustion characteristics of methanol-gasoline blends pool fires in a full-scale tunnel


The combustion characteristics of methanol-gasoline blends pool fires were studied in a series of full-scale tunnel experiments conducted with different methanol and gasoline blends. The parameters were measured including the mass loss rate, the pool surface temperature, the fire plume centerline temperature, the ceiling temperature, the smoke layer temperature profile, the flame height, and the smoke layer interface height. The gasoline components were analyzed by GC-MS. The effects of azeotropism on the combustion characteristics of the different blends were discussed. On the basis of the results of the fire plume centerline temperature, the ceiling temperature, and the flame height, it shows that the tunnel fire regime gradually switches from fuel controlled to ventilation controlled with increasing gasoline fractions in the blends. The fire plume can be divided into 3 regions by the fire plume centerline temperature for the different blends. The N-percentage rule to determine the smoke layer interface height is found to be applicable for tunnel fires with different blends for N = 26.

Fire performance of charring closed-cell polymeric insulation materials: Polyisocyanurate and phenolic foam


Results are presented from 2 series of ad hoc experimental programmes using the cone calorimeter to investigate the burning behaviour of charring closed-cell polymeric insulation materials, specifically polyisocyanurate (PIR) and phenolic (PF) foams. These insulation materials are widely used in the construction industry due to their relatively low thermal conductivity. However, they are combustible in nature; therefore, their fire performance needs to be carefully studied, and characterisation of their thermal degradation and burning behaviour is required in support of performance-based approaches for fire safety design. The first series of experiments was used to examine the flaming and smouldering of the char from PIR and PF. The peak heat release rate per unit area was within the range of 120 to 170 kW/m2 for PIR and 80 to 140 kW/m2 for PF. The effective heat of combustion during flaming was within the range of 13 to 16 kJ/g for PIR and around 16 kJ/g for PF, while the CO/CO2 ratio was within 0.05 to 0.10 for PIR and 0.025 to 0.05 for PF. The second experimental programme served to map the thermal degradation processes of pyrolysis and oxidation in relation to temperature measurements within the solid phase under constant levels of nominal irradiation. Both programmes showed that surface regression due to smouldering was more significant for PF than PIR under the same heat exposure conditions, essentially because of the different degree of overlap in pyrolysis and oxidation reactions. The smouldering of the char was found to self-extinguish after removal of the external heat source.

Numerical evaluation of the flame to solid heat flux during poly(methyl methacrylate) combustion


The total net heat flux of the flame from a burning solid fuel is an important issue for the formulation of comprehensive solid-phase models useful for the fire testing of materials, but measurements are often affected by significant inaccuracy. In this study, an evaluation is conducted using a state-of-the-art model, coupling the descriptions of both gas- and solid-phase processes, for a thick poly(methyl methacrylate) slab burning in a cone calorimeter. It is observed that the total net heat flux (conductive and radiant flame heat fluxes minus surface reradiation losses) remains approximately constant (about 18 kW/m2) as the intensity of the cone irradiance increases from 15 to 60 kW/m2. The influences of some model assumptions and the solid degradation kinetics on this process variable are also assessed. Acceptable agreement is obtained between the predicted and the measured mass loss rates.

Fire-induced reradiation underneath photovoltaic arrays on flat roofs


The impact of the reflection of fire-induced heat from a gas burner was studied experimentally to gain knowledge on the interaction between photovoltaic (PV) panels and a fire on flat roofs. The heat flux was measured in a total of eight points at the same level as the top of the gas burner. The gas burner was placed underneath the center of a PV panel, installed in a geometry similar to a commercial east-west orientated mounting system, and the eight points were symmetrical pairs of two at four different distances from the burner. Measurements were compared with tests with no PV panel, and thereby without the reflection from the PV panel. A significant increase of the received heat flux was recorded, with ascending percentage-wise difference for increased heat release rates. This indicates that PV panels can have a significant contribution in roof fires, primarily because they stimulate fire spread over the roof on which they have been mounted. The received heat flux is higher underneath the most elevated part of the PV panel, due to two important, flame-related reasons: 1) the flame deflection toward the most elevated part of the panel and 2) a nonhomogeneous temperature distribution on the PV panel surface, due to the deflected flame, and thereby a nonhomogeneous emission from the heated PV panel. Finally, the results were very similar for a brand new PV panel and a PV panel tested for the fourth time, except during the period when the thin combustible film underneath the new PV panel is burning, supporting that it is the fire dynamics and not the fire load associated with the PV panels that is promoting fire spread associated with PV panels on flat roofs. With this in mind, the current results are relevant not only for PV panels but also for any inclined roof covering panel with limited combustibility.

Study on the relationship between the particle size distribution and the effectiveness of the K-powder fire extinguishing agent


The relationship between the particle size distribution and the extinguishing effectiveness of the new K-powder fire extinguishing agent has been studied experimentally, to explore the reason of the great extinguishing efficiency exhibited by the new K-powder fire extinguishing agent on Class B fire (liquid fuel fire). The results of the experiment showed that the extinguishing effectiveness increased along with the decrease of the particle size distribution. In addition, a sharp discontinuity appeared around the limiting size, about 40 μm. The powder with the particle size below 40 μm exhibited highly effective extinguishing with the minimum effective extinguishing concentration Cxr = 23 g·m−3, while the powder with the particle size above 40 μm exhibited little fire extinguishing efficiency. Compared with other fire extinguishing agents produced by different substances, the new K-powder fire extinguishing has the bigger limiting size. That means, in the same particle size distribution, the new K-powder fire extinguishing agent contains more highly effective powder than others contain, and is more effective.

Numerical prediction of mass loss rate of expanded polystyrene (EPS) used for external thermal insulation composite systems (ETICS) in cone calorimeter


External thermal insulation composite systems (ETICS) consisting of insulation core and decorative surface materials are quite common in new construction and refurbishment buildings. Expanded polystyrene (EPS) ETICS are widely used. EPS ETICS consist of 3 distinct layers of varying composition and physical structure. The mass loss rate (MLR) and heat release rate play an important role in the evaluation of material reaction-to-fire performance. In the study described in this paper, 2 different numerical simulation tools, Fire Dynamic Simulator (FDS 6.5) and ThermaKin2D, were investigated with respect to their capability to predict the MLR of EPS ETICS products exposed to different fire conditions. The materials were characterised in order to provide suitable input parameters for the models. With accurate input parameters, the mean error between the predicted curve and the experimental MLR curve was calculated as approximately 16% for heat fluxes 30 and 50 kW/m2. The discrepancies between predicted and measured results are ascribed to the flame flux, which is not well modelled. It is found that the flame flux accounts for 15% of external heat flux in FDS 6.5 and for 18.0% of external heat flux in ThermaKin2D.

An investigation of the fire behavior of ETICS facades with polystyrene under fire loads of different size and location


In the context of recent fire damages to façades, and the related discussion about the safety of façade systems in the case of fire, there is a need to discuss the boundary conditions and the phenomena of façade fires based on fundamental investigation. This paper shows the experimental setup, procedure, and results of 5 large-scale fire tests. The tests were carried out on a flat façade with external thermal insulation composite systems based on polystyrene concerning fire loads at the ground in front of the façade. The tests were scientifically monitored by the Institute of Building Materials, Concrete Construction and Fire Safety. The tests differ to the fire tests of the German building ministers in the case of different fire loads and the corner-situation of the investigated façade. The 5 fire tests are the base for systematic investigations to study the examination criteria of the fire phenomena at the façades. Further experimental and numerical investigations will follow.

Effect of nano silica and fine silica sand on compressive strength of sodium and potassium activators synthesised fly ash geopolymer at elevated temperatures


Environment friendly geopolymer is a new binder which gained increased popularity due to its better mechanical properties, durability, chemical resistance, and fire resistance. This paper presents the effect of nano silica and fine silica sand on residual compressive strength of sodium and potassium based activators synthesised fly ash geopolymer at elevated temperatures. Six different series of both sodium and potassium activators synthesised geopolymer were cast using partial replacement of fly ash with 1%, 2%, and 4% nano silica and 5%, 10%, and 20% fine silica sand. The samples were heated at 200°C, 400°C, 600°C, and 800°C at a heating rate 5°C per minute, and the residual compressive strength, volumetric shrinkage, mass loss, and cracking behaviour of each series of samples are also measured in this paper. Results show that, among 3 different NS contents, the 2% nano silica by wt. exhibited the highest residual compressive strength at all temperatures in both sodium and potassium-based activators synthetised geopolymer. The measured mass loss and volumetric shrinkage are also lowest in both geopolymers containing 2% nano silica among all nano silica contents. Results also show that although the unexposed compressive strength of potassium-based geopolymer containing nano silica is lower than its sodium-based counterpart, the rate of increase of residual compressive strength exposed to elevated temperatures up to 400°C of potassium-based geopolymer containing nano silica is much higher. It is also observed that the measured residual compressive strengths of potassium based geopolymer containing nano silica exposed at all temperatures up to 800°C are higher than unexposed compressive strength, which was not the case in its sodium-based counterpart. However, in the case of geopolymer containing fine silica sand, an opposite phenomenon is observed, and 10% fine silica sand is found to be the optimum content with some deviations. Quantitative X-ray diffraction analysis also shows higher amorphous content in both geopolymers containing nano silica at elevated temperatures than those containing fine silica sand.

Influence of horizontal projection on upward flame spread over XPS thermal insulation material


Experimental methods and theoretical analysis are employed to investigate the effects of horizontal projection on upward flame spread over extruded polystyrene thermal insulation material of building façade. The average flame height (Hf) (or area S) drops exponentially as dimensionless projection width (w*) rises, and dropping rates are more significant for wider projection. The decrease of flame area is more remarkable than that of flame height. There exists a low temperature zone which is surrounded by the horizontal projection, the flame, and the façade. The average of maximum temperature ( T¯max) of zone below the projection first decreases and then increases as projection width (w) rises. The temperature dropping rate increases exponentially with w*. T¯max of the zone adjoining the surface of extruded polystyrene sample above the projection decreases linearly with w*. For wider projection (w ≥ 10 cm), the average temperature above it first increases and then drops as height rises. The heat flux history could be divided into 4 stages, ie, ignition stage, smoke heat transfer stage, flame heat transfer stage, and attenuation stage. The average heat flux ( q̇″) at each stage decreases as w rises. The maximum value is observed at the third stage, where q̇″ increases linearly with S.

A method to assess downward flame spread and dripping characteristics of fire-retardant polymer composites


A method is described to assess the flame retardancy of polyethylene composites by measuring both their downward flame spread rates as well as their combined melting and dripping rates on rectangular rods, ignited at their top. The composite materials were produced by mixing pulverized polymer with organic additives of differing particle sizes, shapes, and mass fractions. The resulting mix was melted in a mold, and then it was solidified into rods. The additives were carbonaceous solids with particle sizes spanning from tens of nanometers to tens of micrometers. The mass fraction of the additives in the polymer matrix varied from 1 to 5 wt%. Upon ignition of the upper tips of the polymer composite rods, the downward flame spread rate and the melting and dripping rate were separately assessed by measuring their mass loss and their heights. The addition to polyethylene of finely sized carbonaceous additives at mass fractions of 4 to 5 wt% proved effective at significantly slowing down its downward flame spread by drastically hindering its dripping tendency. The effectiveness of the additives increased with increasing their mass fraction and decreasing their particle size. High mass fractions of carbon additives resulted in wicking, which can enhance radiatively the heat transfer.

Modeling of fire exposure in facade fire testing


In this paper, a comparative simulation study on 3 large-scale facade testing methods, namely, the SP Fire 105, BS 8414-1, and the ISO 13785-2 methods, is presented. Generally good correspondence between simulations and experimental data has been found, provided that thermal properties of the facade material and heat release rates are known; however, the correspondence deviates in close proximity of the fire source. Furthermore, a statistical ensemble for evaluating the effects stemming from uncertainty in input data is used. Here, it was found using this statistical ensemble that the variability was smaller in the ISO 13785-2 compared to the BS 8414-1 method. The heat release rates (HRR) used in the simulations were adopted from measurements except for the ISO method where the information in the standard was used to approximate the HRR. A quantitative similarity between the HRR in the ISO method and the British method was found.

Insightful investigation of smoke suppression behavior and mechanism of polystyrene with ferrocene: An important role of intermediate smoke


Aiming to investigate the smoke suppression mechanism of ferrocene in model polystyrene (PS) during combustion, we exploited the vapor-phase and condensed-phase behaviors. Cone calorimeter testing result showed that 3 wt% ferrocene imparted PS with 56.9% reduction in total smoke production. The analysis of the char after cone calorimeter testing demonstrated that the condensed-phase smoke suppression mechanism was weak owing to the absence of charring behavior. The vapor-phase mechanism was focused on the analysis of the small-molecule smoke precursors and initially formed smoke intermediates. Transmission electron microscopy of initially formed smoke intermediates of PS/3Ferrocene revealed that enormous γ-Fe2O3 nanoparticles from ferrocene participated in the initial formation of smoke intermediates, which subsequently underwent notable thermal oxidation degradation with decreased smoke residue. Thermogravimetric analysis coupled with Fourier transform infrared spectroscopy results manifested that the small-molecule smoke precursors remained almost unchanged with addition of ferrocene. Conclusively, the smoke suppression mechanism with ferrocene predominantly originated from the intensive thermal oxidation of smoke intermediates, which opened a viable route for excellent smoke suppression design.

Fire-retarding properties of nanowollastonite in particleboard


Effects of wollastonite nanofibers on fire-retarding properties of particleboard were studied here. Nanowollastonite (NW) was applied at 5%, 10%, 15%, and 20% based on the dry weight of wood particles. The size range of wollastonite nanofibers was 30 to 110 nm. Two application methods of NW were used: surface application (SA) in which NW was mixed with a water-based paint and sprayed on the specimens, and internal application (IA) in which NW was mixed with the urea-formaldehyde resin. Density was kept constant at 0.68 g/cm3 for all treatments. Specimens of 150 × 130 × 9 mm were prepared, and fire-retarding properties were measured using 2 apparatuses: slide fire test apparatus and fixed fire test apparatus. The obtained results indicated that most fire-retarding properties were improved with the increase in NW content up to 15% when applied internally. More than this amount resulted in decreasing of properties that was partly due to the less wood-chips content and partly due to the absorption of resin by the NW fibers. Surface application showed higher improving effects on the properties. It can be concluded that SA of NW is more effective in improving fire-retarding properties of particleboard; furthermore, 10% of NW is recommended as an optimum level of consumption.

Effect of simulated combustion atmospheres on oxidation and microstructure evolution of aluminum alloy 5052


Among the common materials, metals can be hardly destroyed by flame or the heat emanating from a normal fire. Consequently, investigation on the thermal patterns produced on metallic objects after fire exposure can provide important physical evidence for fire cause/origin determination. Aluminum alloy is widely used in our daily life and the industry; hence, it can be easily found on a domestic or industrial fire scene. In this paper, the aluminum alloy 5052 was exposed in the simulated combustion gases with and without kerosene in the range of 300 to 500°C. Mass change, morphologies, and microstructures of each sample were carefully characterized by thermogravimetric analysis, morphologic observation, and electron microscopy observation with energy-dispersive spectroscopy analysis after exposure. As expected, the microstructure of alloy changed during high temperature exposure. At the same time, an oxide scale formed and was thickened on the surface of alloy. The results reveal that the temperature can significantly affect the growth of oxide scale and the metallurgical microstructure of alloy. It is noteworthy that the presence of kerosene in the combustion gas accelerated oxidation rate and produced oxide scales different from those formed in air. These feature evolutions in surface oxide are expected to offer complementary insight on determining the fire characteristics, such as the exposure temperature, period and whether liquid accelerant is involved.

Temperature of post-flashover compartment fires—Calculations and validation


This paper describes and validates by comparisons with tests a one-zone model for computing temperature of fully developed compartment fires. Like other similar models, the model is based on an analysis of the energy and mass balance assuming combustion being limited by the availability of oxygen, ie, a ventilation-controlled compartment fire. However, the mathematical solution techniques in this model have been altered. To this end, a maximum fire temperature has been defined depending on combustion efficiency and opening heights only. This temperature together with well-defined fire compartment parameters was then used as a fictitious thermal boundary condition of the surrounding structure. The temperature of that structure could then be calculated with various numerical and analytical methods as a matter of choice, and the fire temperature could be identified as a weighted average between the maximum fire temperature and the calculated surface temperature of the surrounding structure as a function of time. It is demonstrated that the model can be used to predict fire temperatures in compartments with boundaries of semi-infinitely thick structures as well as with boundaries of insulated and noninsulated steel sheets where the entire heat capacity of the surrounding structure is assumed to be concentrated to the steel core. With these assumptions, fire temperatures could be calculated with spreadsheet calculation methods. For more advanced problems, a general finite element solid temperature calculation code was used to calculate the temperature in the boundary structure. With this code, it is possible to analyze surrounding structures of various kinds, for example, structures comprising several materials with properties varying with temperature as well as voids. The validation experiments were accurately defined and surveyed. In all the tests, a propane diffusion burner was used as the only fire source. Temperatures were measured with thermocouples and plate thermometers at several positions.

Cone calorimeter testing of foam core sandwich panels treated with intumescent paper underneath the veneer (FRV)


Surfaces of novel foam core sandwich panels were adhered with intumescent fire-retardant paper underneath the veneers (FRV) to improve their flammability properties. The panels were evaluated by means of cone calorimeter test (ASTM E 1354). Variables tested were different surface layer treatments, adhesives used for veneering, surface layer thicknesses, and processing conditions, having the objective of obtaining similar or better flammability as that of solid particle boards. Previous research showed that sandwich panels without FRV compared to panels with FRV generally had much higher heat release rates, somewhat higher heat of combustion and much higher smoke production due to the polymeric foam component of tested panels. The present study shows that using FRV adhered to the surface layer of sandwich panels dramatically improved flammability properties; the best FRV performance resulted from panels produced with thicker face layer (5 mm) and lower press temperature (130°C) and adhered with an acrylic thixotropic adhesive. Such protected foam core particleboard has heat release rate profiles as low as that is typical of commercially available fire-retardant–treated plywood, thus implying a low flammability rating when tested in accordance with both single burn item (Euro Class B anticipated) and steiner tunnel (North America Class A anticipated) tests.

Metal-coordinated epoxy polymers with suppressed combustibility. Preparation technology, thermal degradation, and combustibility test of new epoxy-amine polymers containing the curing agent with chelated copper(II) carbonate


The diethylenetriamine chelate complex of copper(II) carbonate—DETA-CuCO3 (a fire retardant hardener of epoxy resins)—and the CuCO3-containing epoxy-amine polymers—DGEBA/DETA-CuCO3(6), DGEBA/DETA-CuCO3(12), DGEBA/DETA-CuCO3(40), and DGEBA/DETA-CuCO3(80) with suppressed combustibility—have been obtained in the DETA-DGEBA-CuCO3 system (DETA and DGEBA are diethylenetriamine and bisphenol A diglycidyl ether, respectively). The DETA-CuCO3 chelate complex was characterized by X-ray powder diffraction, infrared spectra, and thermal analysis. The thermal gravimetric analysis results have revealed that thermal destruction of DETA-CuCO3 was finished at 400°С, and the maximal temperature of the combustion gases amounted to 520°С. The thermal behavior and combustibility of the CuCO3-containing epoxy-amine polymers were studied using thermal analysis and “Ceramic tube” (CT) method. Thermal gravimetric analysis confirms that incorporation of the DETA-CuCO3 into DGEBA appreciably heightens the thermal stability and antiflammability of the CuCO3-containing epoxy-amine polymers. Results of CT measurement reveal that maximal temperature of the combustion gases under burning of the DGEBA/DETA-CuCO3(12) sample in comparison with unmodified epoxy-amine polymer (DGEBA/DETA) is lowered on 219°С and the loss of weight is decreased on 20.5 wt%. According to ASTM 635-14, ASTM D2863-13, and ASTM D1929-16, the flame propagation rate, limiting oxygen index, and temperatures of ignition and self-ignition have been measured for the elaborated polymer samples.

Effects of opening edge treatment and EPS thickness on EPS external thermal insulation composite systems (ETICS) façade reaction-to-fire performance based on JIS A1310 standard façade fire test method


External thermal insulation composite systems (ETICS) are quite common in constructions. However, the combustible insulation core induces serious fire disasters, especially considering thermoplastic expanded polystyrene (EPS) has been widely used as insulation core. Most of EPS ETICS building fire is caused by window spreading fire. The window opening edge treatment plays an important role in EPS ETICS fire prevention. Presently, in order to investigate optimal opening edge treatment and EPS thickness effects on EPS ETICS reaction-to-fire performance, façade fire tests based on JIS A 1310 standard façade fire test method were carried out by testing a series of EPS ETICS specimens varying EPS thickness, opening edge treatment methods and heating intensity. It is found that back-wrapping is a good opening edge treatment method. When the EPS ETICS specimen is treated by back-wrapping opening edge treatment method, the peak temperature, EPS burn area, time (20 minutes) averaged temperature, and heat flux density become low. The time (20 minutes) averaged temperature of each position from T1 to T5 versus EPS thickness is linear at heating intensity 300 or 600 kW. The averaged ratio of EPS burn area above opening (Sa) and below opening (Sb) is approaching 3.058.

Experimental and numerical study of interactions between sprinklers and natural smoke vents


Real scale experimentations have been conducted in order to investigate interactions that may occur in a compartment where sprinklers and Smoke and Heat Exhaust Vent Systems coexist. Fuel oil spray was used as fire source with steady heat release rate of 400 and 800 kW. Both sprinkler system and natural Smoke and Heat Exhaust Vent Systems were designed according to the French standards. Effect of vent on sprinkler activation time was studied. An analysis of the temperature field inside the compartment was conducted while vent was opened prior or after sprinkler activation. Simulations of the experiments were also carried out with Fire Dynamics Simulator v.6 for validation purpose and also to provide supplementary data regarding soot flow rate and energy extracted at the vent.

Enhancing egress drills: Preparation and assessment of evacuee performance


This article explores how egress drills—specifically those related to fire incidents—are currently used, their impact on safety levels, and the insights gained from them. It is suggested that neither the merits of egress drills are well understood, nor the impact on egress performance well characterized. In addition, the manner in which they are conducted varies both between and within regulatory jurisdictions. By investigating their strengths and limitations, this article suggests opportunities for their enhancement possibly through the use of other egress models to support and expand upon the benefits provided. It is by no means suggested that drills are not important to evacuation safety—only that their inconsistent use and the interpretation of the results produced may mean we (as researchers, practitioners, regulators, and stakeholders) are not getting the maximum benefit out of this important tool. © 2017 Her Majesty the Queen in Right of Canada. Fire and Materials StartCopText© 2017 John Wiley & Sons, Ltd.

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On a planar thermal analysis of intumescent coatings


The paper discusses a complex model for a nonstationary planar thermal analysis of expandable intumescent coatings. Following the existing one-dimensional models, we develop novel and improved equations for the two-dimensional thermal analysis of intumescent coatings. A progressive expansion due to chemical reactions, phase changes, and the time and temperature-dependent thermal properties of the coating are considered. In the heating process, the coating may locally experience virgin, intumesced, or charred phases, and their transition with time. The rate of the density loss due to the pyrolysis reaction is described with the Arrhenius equation. The thickness of the coating is assumed to increase enormously during the pyrolysis. Consequently, the energy and mass equilibrium equations are formulated with respect to both the deformed and undeformed configuration. Since most of material properties of commercial products are not given by manufacturers, an innovative procedure is proposed to determine the time-dependent thermal conductivities and remaining fundamental properties of the coating from the set of measured temperatures. This, together with the two-dimensional formulation of the thermal equations with respect to the undeformed configuration, makes the present model unique and appropriate for the thermal analyses of an arbitrary steel cross section protected with intumescent coatings.

Oxidation behavior of carbon steel in simulated kerosene combustion atmosphere: A valuable tool for fire investigations


Fire investigations aim to establish the origin and cause of fires by collecting and analyzing the comprehensive fire-related evidences. Metallic materials exposed to the fire scene environments are usually subjected to melting and/or high-temperature oxidation, and they have been considered vital parameters for temperature determination, as recommended in NFPA 921. The oxide characteristics obtained from the conventional fire investigations primarily rely on simple visual observations such as the variations in oxide color, the so-called “oxidation patterns.” However, such information is not sufficiently convincing due to the complex nature of oxides formed in the fire scene. The oxide color is strongly affected by the type of oxide, the oxide thickness, the concentration of contaminant, and the interactions among different oxides. In this study, Q235 structural steel samples have been exposed to high-temperature air and simulated kerosene combustion conditions at certain temperatures and for indicated periods. The oxidation rate was examined by thermogravimetric analysis. The morphologies and microstructures of the oxide scales were investigated by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractions. The results show that the oxide properties are strongly dependent on the oxidation temperature and oxidation atmospheres. These oxidation behaviors are expected to provide useful information on identifying fire characteristics.

The ammonium nitrate explosion at West, Texas: A disaster that could have been avoided


On April 17, 2013, an explosion of ammonium nitrate (AN) fertilizer stored at the West Fertilizer Company resulted in 15 deaths, 260 injuries, and the destruction of a sizable portion of the town. AN fertilizer is classified as an oxidizer, not as an explosive; nonetheless, it is a chemical which can detonate, and there is a century's worth of history of such explosions, some of them in manufacturing operations, but many in storage or transport. A review of incidents showed that 100% of AN fertilizer explosions in storage or transport had a single cause—an uncontrolled fire. Thus, AN fertilizer explosions in storage are preventable accidents, because technology to preclude uncontrollable fires also has been available for a century. In the case of transport accidents, uncontrolled fires may not be avoidable. However, technologies exist that can make AN less likely to explode, and to show greatly reduced explosion intensity, if driven to explosion. None of these safety measures were in place for this disaster. Details of necessary fire safety measures and the effectiveness and utility of existing regulations for AN are examined. This is important because most AN storage facilities in the United States are similarly inadequate in their fire safety.

Experimental research on the burning behavior of dragon juniper tree


Tree crown fire is one of the extreme fire behaviors in the wildland-urban interface. This paper presents an experimental study on the burning behaviors of single and triple dragon juniper trees. The mass loss, flame height, plume temperature, radiation, and fire interaction are measured. It is found that the foliage moisture content and flame mergence dominate the mass consumed percentage (defined as the ratio of the total mass loss to initially total mass), while the tree crown height and flame mergence determine the flame height. The peak mass loss rate is mainly affected by the moisture content and tree species. For triple tree fires, the peak mass loss rate is also affected by the spacing due to the coupled effects of heat feedback enhancement and air entrainment restriction. Results also show that the flame height significantly increases as the spacing decreases. The spacing holds a significant effect on the fire plume temperature distribution and thermal radiation field. Empirical correlations are also developed for the flame height, radial temperature, and radiant heat flux distribution based on physical interpretation of the tree burning behaviors.

Surface sedimentation and adherence of Nano-SiO2 to improve thermal stability and flame resistance of melamine-formaldehyde foam via sol-gel method


Melamine-formaldehyde foam possesses intrinsic flame retardance; however, relative poor thermal stability and a certain amount of heat release rate restrict its applications in heated environment to a degree. In the present research, sol-gel method has been adopted to precipitate nano-SiO2 particles on the surface of the melamine-formaldehyde foam's fibers to construct a protective inorganic gel layer. Taking advantages of the shielding effects of the gel layer, the thermal-oxygen degradation of the foam can be greatly retarded during heating; hence, the thermal stability is remarkably improved, and the flame retardance is further enhanced. In addition, introducing a small amount of membrane-forming agent in the sol-gel system can make the depositional nano-SiO2 particles well adhered to avoid dusting.

The intumescent flame-retardant biocomposites of poly(lactic acid) containing surface-coated ammonium polyphosphate and distiller's dried grains with solubles (DDGS)


This work aims to develop the poly(lactic acid) (PLA) biocomposites with high flame-retardant performance, which can be applied in electronic and electrical devices as well as automotive parts. First, an intumescent flame retardant composed of ammonium polyphosphate (APP) as the acid source and the blowing agent, and the distiller's dried grains with solubles (DDGS) as the natural charring agent was designed. The surfaces of DDGS and APP were coated by degradable polymeric flame-retardant resorcinol di(phenyl phosphate) (RDP), and the coating effects were analyzed. And then the flame-retardant biocomposites of PLA with RDP-coated DDGS (C-DDGS) and RDP-coated APP (C-APP) were prepared. The limited oxygen index value of the biocomposites with loading of 15 wt% C-DDGS and 15 wt% C-APP reached 32.0%, and UL-94 V-0 was attained. The biocomposites also had good mechanical properties and the tensile strength of this sample reached about 57 MPa. Finally, the char residues after burning were analyzed and the flame-retardant mechanism was discussed.

Flammability of wood plastic composites prepared from plastic waste


The flammability of wood plastic composites manufactured from recycled plastics was investigated by using the cone calorimetry technique. The peak of the heat release rate was 12% to 25% lower compared to references produced from pure polyethylene- and polypropylene-based composites. The total heat capacity and mass loss rate were also smaller for recycled material compared to the references. The stability of the composites was improved due to the presence of various thermally stable compounds, eg, traces of fire retardants, pigments, and other additives and impurities that can be present in recycled material. Incorporation of carbon black into the secondary materials did not reduce the peak of the heat release rate, but the total heat capacity and mass loss rate decreased further.

Temperature distribution of the straight bar, fixed into a heated plane surface


The authors present the first stage of their theoretical and experimental investigations focused on the fire protection of the steel structures using intumescent paint. In this initial stage, their results concerning the temperature distribution law (the theoretical law is validated by effective meticulously conducted measurements) are described. Their original testing bench destined to perform high-accuracy monitoring of the temperature distribution along straight bars, having a given αg angular positioning with respect to the vertical direction is also described. By involving this testing bench in meticulously conducted experiments, the authors obtained both the effective temperature distribution along the bars and also validated the theoretical (exponential) thermal distribution law. By searching experiments, they also validate the m = const. hypothesis with respect to the massive cross-sectional bars. Among their further goals, one can mention the searching experimental analysis on the validity of the m = const. hypothesis for the tubular cross-sectional bars, followed by a combined experimental and numerical analysis of the 2-D and 3-D (unprotected and protected with intumescent paint layer) structures, as well as the paint layer's thickness optimisation, too.

Effect of phytic acid–modified layered double hydroxide on flammability and mechanical properties of intumescent flame retardant polypropylene system


Phytic acid–modified layered double hydroxide (Ph-LDH) was synthesized via coprecipitation method and subsequently was used in polypropylene (PP) by combining with an ammonium polyphosphate (APP) via melt compounding method. The synergistic effect between APP and Ph-LDH on the thermal stability, flammability, and mechanical properties of the resultant PP composites was investigated by thermogravimetric analysis, limiting oxygen index, vertical burning test (UL-94), cone calorimeter tests, tensile test, and impact test. Morphologies of the chars obtained from the samples after the cone calorimeter tests were studied by scanning electron microscopy. The combination of APP and Ph-LDH slightly influenced the impact and tensile properties of PP. Also, the synergistic effect between APP and Ph-LDH occurred in the cone calorimeter test. Moreover, the combination of APP and Ph-LDH produced better quality char that effectively suppressed the spread of the flame and volatile and finally extinguished the fire.

Gypsum board failure model based on cardboard behaviour


This study aims to analyse the importance of gypsum plasterboard cardboard for fire resistance. A new hypothesis considering the failure based on the cardboard degradation is defined. This hypothesis comes from the thermal analysis of gypsum and cardboard performed in the simultaneous thermal analysis apparatus. Simultaneous thermal analysis results also allow defining the dehydration process of the gypsum. A numerical model that considers gypsum dehydration and the failure hypothesis has been developed by using Fire Dynamic Simulator. This numerical model is validated against 6 fire resistance tests. Results show that we can appropriately tune the numerical model (for predicting time to failure) based on the thermal properties of cardboard.

Influence of out-of-plane fiber orientation on reaction-to-fire properties of carbon fiber reinforced polymer matrix composites


This work investigates the influence of the out-of-plane orientation of carbon fibers on the reaction-to-fire characteristics of polymer matrix composites. A deep insight into combustion processes is gained, which is necessary to fully understand and assess advantages of composites with out-of-plane fiber angles. Epoxy-based Hexply 8552/IM7 specimens with primarily low fiber angles between 0° and 15° are characterized by cone calorimetry. Heat release during fire is greatly affected by the out-of-plane fiber angle because of the thermal boundaries created by the fibers. The advancement of the pyrolysis front during fire was determined from peak heat release rates and validated by temperature measurements along the back surface of the panels, representing a novel method of determining position-dependent pyrolysis migration velocity. These measurements show a transverse shift in pyrolysis front velocity for increasing out-of-plane fiber angles. Pyrolysis pathways between the fiber boundaries facilitate faster combustion through the composite thickness, especially for increasing angles from 0° to 15°. It was determined that under the chosen conditions, the pyrolysis front advances approximately 4 times faster when propagating parallel to the fibers than perpendicular.