Assessment of fire behaviour of high‐speed trains' interior materials: small‐scale and full‐scale fire tests

The development of fire‐safety measures for high‐speed passenger trains has been focused on preventing fire initiation or delaying fire growth and spread through small‐scale tests of the materials used in trains. However, new fire‐safety approaches for trains consider a systemic approach. This approach considers numerous global factors that influence fire dynamics, such as the influence of vehicle design, selection of materials, and active and passive protection systems installed. In the present paper, the results of small‐scale and full‐scale tests carried out on the new generation of high‐speed trains operating in Spain are presented. This rolling stock is classified as category B according to the Technical Specification for Interoperability and Operation Category 3 according to EN 45545–1. The results confirmed good fire behaviour using both approaches (small and full‐scale tests). Additionally, several analyses have been performed, including an analysis of the quality of materials used for making different components of the passenger compartment and the influence of ignition source position on fire development. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental study of tenability during a full‐scale motorcoach tire fire

Full‐scale fire experiments were conducted at the National Institute of Standards and Technology (NIST) to investigate tire fire interactions with the passenger compartment of a motorcoach. A single full‐scale experiment with a partially furnished interior was conducted to investigate tire fire growth within the passenger compartment and the onset of untenable conditions. A tire fire was initiated using a burner designed to imitate the frictional heating of hub and wheel metal caused by failed axle bearings, locked brakes, or dragged blown tires. Measurements of interior and exterior temperatures, interior heat flux, heat release rate, toxic gases, and visibility were performed. Standard and infrared videos and still photographs were also recorded. The results of this single experiment showed that after fire penetration into the passenger compartment, the tenability limits were reached within 8 minutes near the fire and within 11 minutes throughout the passenger compartment.     

Numerical simulations of a full‐scale cable tray fire using small‐scale test data

This paper presents a computational fluid dynamics (CFD)‐based modeling strategy for the prediction of cable tray fire development. The methodology is applied to a set of five horizontal trays (each 2.4‐m long and 0.45‐m wide) that are positioned with a 0.3‐m vertical spacing and set up against an insulated wall. Each tray contains 49 power PVC cables. Ignition is performed with an 80‐kW propane burner centrally positioned at 0.2 m below the lowest tray. A collection of four groups of cables per tray (made of one homogeneous material) is considered. These groups are separated by longitudinal slots of air to “mimic” their relatively “loose arrangement.” The thermal properties and surface ignition temperature are estimated from cone calorimetry (CC). When the ignition temperature is reached, the cables burn according to a prescribed heat release rate per unit area (HRRPUA) profile obtained from CC, as is or in a modified shape. A realistic flame pattern is predicted. Furthermore, using only data from CC, the peak HRR is underpredicted, and the time to reach the peak is overpredicted. The proposed “design” for the modified HRRPUA CC‐profile significantly improves the results.     

Survey of small‐scale flame spread test results of modern fabrics

The flammability of apparel worn on a person has one of the highest ratios of fire fatalities per fire, and there are few statutory requirements. A series of evaluations was conducted on the flammability of 50 fabrics (both cellulosic and thermoplastic) using the (now withdrawn) NFPA 701 small‐scale test. The fabrics covered a broad range of areal densities (weights) and many were not intended for apparel. A series of conclusions were reached. In particular, it is apparent that the following primary correlation exists between fabric weight and flammability: the heavier the fabric the better it behaves in a fire. Secondarily, however, the type of fabric also strongly affects this conclusion. This paper presents the results of the testing and offers an analysis. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparison of simulated wet bench fires with small‐ and intermediate‐scale fire tests

Fire hazard studies of clean room facilities indicated that significant losses due to fire may occur in the semiconductor industry. The present study reports the results of full‐scale wet bench fire tests conducted (1) to assess the fire hazards of existing wet bench materials not meeting the listing requirement of NFPA 318, (2) to assess the impact on wet bench fires of engineered materials with improved flammability characteristics, and (3) to compare the observed fire behavior with the results of simpler small‐ and intermediate‐scale fire tests using the same materials. The full‐scale wet bench fires were observed to be consistent in terms of chemical heat release rate, fire propagation, and smoke generation with the results of the small‐ and intermediate‐scale test results. The simpler fire tests are incorporated in FM Approvals 4910 certification for materials to be used in semiconductor fabrication facilities. The small‐scale test protocol is also standardized in NFPA 287. Copyright © 2008 John Wiley & Sons, Ltd.     

Evaluation of fire performance of organic fire retardant free acrylic based coatings applied on various building materials by cone calorimetric method

Fire performance of water‐based plaster systems containing acrylic copolymer binder and non‐flammable mineral and ceramic fillers intended for decorative coating application was determined by cone calorimetric method. The coatings were applied on common building substrate materials used in construction sector, namely, Medium Density Fibre (MDF) boards, Gypsum Boards (GIB) and Stainless Steel (SS), and the different plaster finishes attempted on these substrates were Tierrafino, Suave and Bone China respectively. Group numbers of the different test samples were also evaluated following the Kokkala method. Based on various measurements, especially heat release, smoke evolution, mass loss data and the Group number estimates, it is evident that these organic fire retardant free coatings can offer good fire safety if applied on appropriate substrates like GIB or SS. Copyright © 2016 John Wiley & Sons, Ltd.     

A guide to characterizing heat release rate measurement uncertainty for full‐scale fire tests

Accurate heat release rate measurements provide essential information to defining the fire safety characteristics of products. The size, complexity, and cost of full‐scale fire tests make achieving accurate and quantitative results a serious challenge. A detailed uncertainty analysis of a large‐scale heat release rate measurement facility is presented as a guide to the process of estimating the uncertainty of similar facilities. Quantitative heat release rate measurements of full‐scale fires up to 2.7 MW were conducted using the principle of oxygen consumption calorimetry. Uncertainty estimates were also computed for the heat input measurements from a well‐controlled natural gas burner. The measurements of heat input and heat release rate were performed independently, and the discrepancy between the two was well within the uncertainty limits. The propagation of uncertainty was performed at the level of voltage and temperature measurements, which avoided using mutually dependent measurement parameters. Reasons for the significant contribution to the combined uncertainty from the oxygen concentration and exhaust flow measurements are demonstrated. Also presented is a first‐order effort to account for the uncertainty due to factors in full‐scale fire tests such as operator error and environmental influences that are not modeled by the heat release rate equation. Published in 2008 by John Wiley & Sons, Ltd.     

Flammability of oil‐based painted gypsum wallboard subjected to fire heat fluxes

The flammability of painted gypsum wallboard (GWB) exposed to fire heat fluxes is investigated. GWB samples coated with multiple layers of alkyd/oil‐based paint are subjected to constant incident heat fluxes of 35, 50 and 75 kW/m² in the Cone Calorimeter for periods of 5, 10 and 15 min. A number of coats of alkyd/oil‐based interior semi‐gloss enamel paint, including 1, 2, 4, 6 and 8 coats, are applied over a single coat of oil‐based primer to the exposed surface of 16 mm (5/8 in.) thick type X GWB. Unpainted type X GWB is also evaluated under the same exposure conditions. The potential for upward flame spread based on the Cone Calorimeter results is evaluated. The occurrence of paint ‘blistering’ is observed to have a significant effect on the time to ignition and consequently on the potential for upward flame spread. Further work is needed to evaluate the conditions under which ‘blistering’ will occur and its effects on the potential for surface flame spread on painted gypsum wallboard. Copyright © 2004 John Wiley & Sons, Ltd.     

Investigation of smoke gases and temperatures during car fire – large‐scale and small‐scale tests and numerical investigations

The hazards for passengers during vehicle fires result from the increasing temperature and the emitted smoke gases. A fire was set on a car to investigate the development of temperature and of gaseous fire products in the passenger compartment. The study was based on a full‐scale test with a reconstructed scene of a serious car fire. The aim of this work was to identify the conditions for self‐rescuing of passengers during a car fire. A dummy, equipped with several thermocouples, was placed on the driver's seat. Also, the smoke gases were continuously collected through a removable probe sensor corresponding to the nose of the dummy in the passenger compartment and analyzed using Fourier transform infrared spectroscopy. Additionally, several car components were investigated in the smoke density chamber (smoke emission and smoke gas composition). It was found that the toxic gases already reached hazardous levels by 5 min, while the temperatures at the dummy were at that time less than 80 °C. The toxicity of smoke gases was assessed using the fractional effective dose concept. The various experimentally parameters (temperature and smoke gas composition) were implemented into numerical simulations with fire dynamics simulator. Both the experimental data and the numerical simulations are presented and discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental study on the burning behaviour of Pinus halepensis needles using small‐scale fire calorimetry of live,aged and dead samples

Limited research has been conducted on the burning characteristics of live fuels, which are commonly assumed to behave like moist dead fuels. We use small‐scale laboratory calorimetric experiments to investigate the differences in fire dynamics between live and dead Pinus halepensis needles. The study includes laboratory‐aged samples and different moisture conditions (fresh or oven dry). A series of ten fire behaviour parameters are extracted from the measurements to identify and quantify differences. The main parameters are the following: time to ignition; flaming time; mass loss pre‐ignition, during flaming, and during smouldering; peak power; effective heat of combustion; mean and peak CO/CO₂; and radiative fraction. Using these parameters, we show that the most flammable samples are fresh dead and aged needles, followed by dry dead and dry live needles. The least flammable is fresh live needles. Live needles ignite about four times slower, and burn with ~60% lower power and ~50% lower heat of combustion than dead needles. Aged needles resemble most closely the behaviour of dead needles, but many fire behaviour parameters were significantly different. The results confirm the importance of moisture content in the burning behaviour of pine needles, but the differences between live and dead samples cannot be explained solely in terms of moisture but require consideration of plant chemistry and sample drying. © 2015 The Authors. Fire and Materials published by John Wiley & Sons Ltd.     

Thermal and fire degradation of recycled and polluted polypropylene‐based materials

In this study, the effect of processing cycles and two pollutants (engine oil (HM) and ethylene glycol (EG)) on the thermal and rheological properties of polypropylene‐based materials (108MF97 and 7510) has been studied. It was investigated if polymers coming from bumper face bar could keep their properties and can be reused after recycling. The different results demonstrate that the two polymers that were polluted and recycled do not show any decrease of their intrinsic properties. Moreover, for one of the two polymers (108MF97), the presence of engine oil enables to increase the thermal stability and reaction to fire. Finally, it appears that the reuse of such polymers is possible. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Towards a methodology for the characterization of fire resistive materials with respect to thermal performance models

A methodology is proposed for the characterization of fire resistive materials with respect to thermal performance models. Typically in these models, materials are characterized by their densities, heat capacities, thermal conductivities, and any enthalpies (of reaction or phase changes). For true performance modelling, these thermophysical properties need to be determined as a function of temperature for a wide temperature range from room temperature to over 1000°C. Here, a combined experimental/theoretical/modelling approach is proposed for providing these critical input parameters. Particularly, the relationship between the three‐dimensional microstructure of the fire resistive materials and their thermal conductivities is highlighted. Published in 2005 by John Wiley & Sons, Ltd.     

A slug calorimeter for evaluating the thermal performance of fire resistive materials

The utilization of a slug calorimeter to evaluate the thermal performance of fire resistive materials (FRMs) is presented. The basic specimen configuration consists of a ‘sandwich’, with a square central stainless‐steel plate (slug) surrounded on two sides by the FRM. This sandwich configuration provides an adiabatic boundary condition at the central axis of the slug plate that greatly simplifies the analysis. The other four (thin) sides of the steel plate (and FRM specimens) are insulated using a low thermal conductivity fumed‐silica board. Two metal plates manufactured from a high temperature alloy provide a frame for placing the entire sandwich specimen slightly in compression. The entire configuration is centrally placed at the bottom of an electrically heated box furnace and the temperatures of the metal slug and exterior FRM surfaces are monitored during multiple heating and cooling cycles. Knowing the heat capacities and densities of the steel slug and the FRM, an effective thermal conductivity for the FRM can be estimated. The effective thermal conductivity of the FRM will be influenced by its true thermal conductivity and by any endothermic or exothermic reactions or phase changes occurring within the FRM. Preliminary tests have been conducted on two commonly used FRMs and on a non‐reactive fumed‐silica board to demonstrate the feasibility of the method. Published in 2005 by John Wiley & Sons, Ltd.     

Influences of specimen size and heating mode on the ignitability of polymeric materials in typical small‐scale fire test conditions

Small‐scale fire tests including the Underwriters Laboratories 94 (UL94) vertical burning test and the cone calorimeter test are widely used. In this paper, the ignition times of materials heated by the conical heater of a cone calorimeter and the UL94 flame were measured. It was found that for polymer bars heated by the UL94 flame, the ignition time is relatively short and increases with the specimen thickness. But the contribution of the specimen thickness to the delay of the ignition time is limited. The intrinsic properties of materials play a more important role in the ignition time than the specimen thickness. In addition, respectively corresponding to one‐dimensional, two‐dimensional, and three‐dimensional heat transfer, three heating modes of the UL94 flame were presented and compared with the conical heater. It was found that whether the heat source is the conical heater or the UL94 flame, the ignition time depends on the heat flux and the multidimensional heat transfer. The ignition time decreases with the increasing heat flux, and the magnitude order of the ignition time might drop when the heating mode changes from one‐dimensional to multidimensional heat transfer. Copyright © 2011 John Wiley & Sons, Ltd.     

DOPO‐VTS‐based coatings in the realm of fire retardants for cotton textile

The work elucidates the feasibility of incorporation of phosphorus‐silicon containing fire retardant (10‐(2‐trimethoxysilyl‐ethyl)‐9‐hydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide [DOPO‐VTS]) into nanosol coating solutions by cohydrolysis cocondensation reaction of DOPO‐VTS with tetraethoxysilane precursor (TEOS). Impregnation of cotton with the organophosphorus silane in a form of nanosol dispersion afforded better fire retardancy of such samples compared to pure DOPO or TEOS‐treated cotton indicating synergism between phosphorus and silicon containing species in a condensed phase. The detailed analysis by TGA‐MS and SEM pointed to the fact that DOPO‐VTS acts as a promoter of cotton degradation which, in turn, results in acceleration of the charring process and formation of compact char in contrast to TEOS‐treated samples. Further analysis of the char by XPS confirmed high content of carbonaceous residue in the case of DOPO‐VTS‐treated samples while mainly siliceous component was left in the char in case of cotton treated with TEOS. Standard flammability test (EN ISO 15025:2008) additionally confirmed the absence of smoldering and better overall fire performance of the DOPO‐VTS samples in contrast to TEOS‐treated samples. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41955.     

Effects of upholstery materials on the burning behavior of real‐scale residential upholstered furniture mock‐ups

Fire spread and growth on real‐scale four cushion mock‐ups of residential upholstered furniture (RUF) were investigated with the goal of identifying whether changes in five classes of materials (barrier, flexible polyurethane foam, polyester fiber wrap, upholstery fabric, and sewing thread), referred to as factors, resulted in statistically significant changes in burning behavior. A fractional factorial experimental design plus practical considerations yielded a test matrix with 20 material combinations. Experiments were repeated a minimum of two times. Measurements included fire spread rates derived from video recordings and heat release rates (HRRs). A total of 13 experimental parameters (3 based on the videos and 10 on the HRR results), referred to as responses, characterized the measurements. Statistical analyses based on Main Effects Plots (main effects) and Block Plots (main effects and factor interactions) were used. The results showed that three of the factors resulted in statistically significant effects on varying numbers of the 13 responses. The Barrier and Fabric factors had the strongest main effects with roughly comparable magnitudes. Foam was statistically significant for fewer of the responses and its overall strength was weaker than for Barrier and Fabric. No statistically significant main effects were identified for Wrap or Thread. Multiple two‐term interactions between factors were identified as being statistically significant. The Barrier*Fabric interaction resulted in the highest number of and strongest statistically significant effects. The existence of two‐term interactions means that it will be necessary to consider their effects in approaches designed to predict the burning behavior of RUF.     

A New Halogen‐Free Flame Retardant Based on 9,10‐Dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide for Epoxy Resins and their Carbon Fiber Composites for the Automotive and Aviation Industries

The pyrolysis and fire behavior of halogen‐free flame‐retarded DGEBA/DMC, RTM6 and their corresponding 60 vol.‐% carbon fibers (CF) composites were investigated. A novel phosphorous compound (DOPI) was used. Its action is dependent on the epoxy matrix. DGEBA/DMC and DOPI decompose independently of each other. Only flame inhibition occurs in the gas phase. RTM6 shows flame inhibition and a condensed phase interaction increasing charring. Both mechanisms decrease with increasing irradiance, whereas in RTM6‐CF charring is suppressed at low ones. RTM6 + DOPI shows a higher LOI (34.2%) than DGEBA/DMC + DOPI and a V‐0 classification in UL 94. Adding CF only enhances the LOI, DOPI + CF leads to a superposition in LOI for DGEBA/DMC‐CF + DOPI (31.8%, V‐0) and a synergism for RTM6‐CF + DOPI (47.7%, V‐0).