Showing papers in "Fire and Materials in 2017"

Evacuation response behaviour of occupants in a large theatre during a live performance

Abstract: This paper presents the results of an unannounced theatre evacuation involving 1200 occupants. The evacuation took place towards the end of a live theatre performance in the Marlowe Theatre in Kent, UK. In particular, Response Phase behaviours are discussed, and response time data is presented. A significant finding of this work which is different to other reported work is that the occupant response time distribution, while following the typical log-normal distribution is related to the geometrical positioning of the occupants relative to proximity to exit aisles and exits. Response time is found to increase relative to seat distance from the exit aisles and distance of the seat row to an exit. The identified trends in response time distribution will have a profound impact on the analysis of evacuation times and congestion levels determined using agent based evacuation models and so should be represented within these models. Based on these findings, a generalised methodology is proposed to distribute response time within a theatre for use in evacuation simulation applications. Further experimental analysis is required to determine whether these observations can be generalised and applied to other seated venues such as cinemas, music venues and sports arenas.

The effect of traditional flame retardants, nanoclays and carbon nanotubes in the fire performance of epoxy resin composites

Abstract: SUMMARY The effectiveness of distinct fillers, from micro to nano-size scaled, on the fire behaviour of an epoxy resin and its carbon fibre reinforced composites was assessed by cone calorimetry The performance was compared not only regarding the reaction to fire performance, but also in terms of thermal stability, glass transition temperature and microstructure Regarding the fire reaction behaviour of nanofilled epoxy resin, anionic nanoclays and thermally oxidized carbon nanotubes showed the best results, in agreement with more compact chars formed on the surface of the burning polymer For carbon fibre reinforced composite plates, the cone calorimeter results of modified resin samples did not show significant improvements on the heat release rate curves Poorly dispersed fillers in the resin additionally caused reductions on the glass transition temperature of the composite materials Copyright © 2016 John Wiley & Sons, Ltd

Effect of boron compounds on fire protection properties of epoxy based intumescent coating

Abstract: Summary The aim of this study was to investigate the effect of boron compounds on fire protection properties of intumescent coating based on ammonium polyphosphate (APP). Three kinds of boron compounds namely boric acid (BA), zinc borate (ZB) and melamine borate (MB) were used. Total amount of flame retardant additive was kept constant at 30 wt%, and boron compounds were used at three concentrations of 1, 3 and 5 wt%. Thermogravimetric analysis (TGA), Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) and fire test were conducted for the determining the fire performance of intumescent coating. According to fire test results, BA and MB showed synergistic effect at 1 wt% loading. ZB showed antagonistic effect at all concentrations. Fire protection effect of intumescent coating decreased as the added amount of boron compound increased regardless of boron compound type because of suppression of intumescence. Copyright © 2016 John Wiley & Sons, Ltd.

Revealing the inner secrets of intumescence: Advanced standard time temperature oven (STT Mufu+)—μ‐computed tomography approach

Abstract: SUMMARY Intumescent coatings have been used for fire protection of steel for decades, but there is still a need for improvement and adaptation The key parameters of such coatings in a fire scenario are thermal insulation, foaming dynamics, and cohesion The fire resistance tests, large furnaces applying the standard time temperature (STT) curve, demand coated full-scale components or intermediate-scale specimen The STT Mufu+ (standard time temperature muffle furnace+) approach is presented It is a recently developed bench-scale testing method to analyze the performance of intumescent coatings The STT Mufu+ provides vertical testing of specimens with reduced specimen size according to the STT curve During the experiment, the foaming process is observed with a high-temperature endoscope Characteristics of this technique like reproducibility and resolution are presented and discussed The STT Mufu+ test is highly efficient in comparison to common tests because of the reduced sample size Its potential is extended to a superior research tool by combining it with advanced residue analysis (μ-computed tomography and scanning electron microscopy) and mechanical testing The benefits of this combination are demonstrated by a case study on 4 intumescent coatings The evaluation of all collected data is used to create performance-based rankings of the tested coatings

An international survey and full‐scale evacuation trial demonstrating the effectiveness of the active dynamic signage system concept

Abstract: Rapid evacuation from large buildings is challenging due to their complex layout making wayfinding difficult. While emergency signage is widely used to aid wayfinding, recent research demonstrates that only 38% of people perceive conventional exit signs. Furthermore, conventional signage only conveys single and passive information and so cannot adapt to changing conditions. The EU FP7 GETAWAY project addresses this problem through the development of a unique and innovative Intelligent Active Dynamic Signage System (IADSS), which routes occupants to their optimal exits during an evolving incident. This paper presents two key steps in the development of the IADSS concept. First, a novel negated signage concept identifying that an exit route is no longer viable was devised and tested using an international survey. The results demonstrate that the negation concept can be clearly understood by over 90% of the sample. The second step involved two full-scale evacuation trials in a rail station that demonstrated that it was possible to direct over 60% of the participants to the targeted exit through the use of the Active Dynamic Signage System (ADSS). The ADSS makes use of the negated signage concept and a development involving a green flashing arrow within the standard emergency exit sign.

Poly(vinyl chloride) and its fire properties

Abstract: Summary This work provides an up-to-date review of the fire properties of poly(vinyl chloride) (PVC) materials, both rigid (unplasticized) and flexible (plasticized) The fire properties addressed include ignitability, ease of extinction (oxygen index), flame spread (small scale and intermediate scale), heat release, smoke obscuration, smoke toxicity, hydrogen chloride emission and decay, and performance in real-scale fires This comprehensive review includes a wide selection of references and tables illustrating the properties of PVC materials in comparison with those of other polymeric materials, including, in many instances, wood materials The work puts these fire properties in perspective, showing that the heat release rate (the key fire property) of rigid PVC (and that of properly flame-retarded flexible PVC) are among the lower values found for combustible materials This work also shows that the smoke toxicity and smoke obscuration resulting from burning PVC materials in real-scale fires is in the same range as those of other materials

School egress data: comparing the configuration and validation of five egress modelling tools

Abstract: Data were collected between 2011 and 2014 from five evacuations involving the same school buildings located in Spain. Children from 6 to 16 years of age were observed during the evacuation exercises. Background information was collected on key factors deemed to influence evacuation performance: a description of the geometry, the population involved, the procedures employed and the organization of the drills conducted. Using live observations and video footage of these drills, evacuation data were collected, focusing on the pre-evacuation times, the routes employed, the travel speeds adopted and thearrival times. These data informed a range of a posteriori simulations, conducted by using four computer models (buildingEXODUS, MassMotion, Pathfinder and STEPS) and the Society of Fire Protection Engineering hydraulic model (i.e. Society of Fire Protection Engineering hand calculations). Comparisons were drawn between the models’ output and against the observed outcome for one of the trials to determine the accuracy of the model predictions given that they were configured by using the initial conditions for a specific evacuation. The purpose of this work is to (1) provide insight into the configuration of these models for equivalent scenarios, (2) examine any variation in the simulated conditions given equivalent initial conditions, and (3) provide suggestions on how to perform validation studies for multiple evacuation models. (Less)

Burning Down the Silos: Integrating new perspectives from the social sciences into human behavior in fire research.

Abstract: Summary The traditional social science disciplines can provide many benefits to the field of human behavior in fire (HBiF). First, the social sciences delve further into insights only marginally examined by HBiF researchers, in turn, expanding the depth of HBiF research. In this paper, I present examples of studies from the fields of social psychology and sociology that would expand HBiF research into non-engineering or ‘unobservable’ aspects of behavior during a fire event. Second, the social sciences can provide insight into new areas of research; in turn, expanding the scope of HBiF research. In this section, I introduce pre and post-fire studies and explore potential research questions that fall outside of the response period of a fire, the phase upon which, most focus is currently placed. Third, the social sciences elucidate the value of research methods available to study human behavior. Qualitative research methods are specifically highlighted. These three benefits will allow HBiF researchers to collect a wider range of data, further develop and expand current behavioral knowledge, and increase the impact of this research for both social and engineering applications. Finally, I end with a discussion on possible ways to better integrate the social sciences within human behavior in fire. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Potential for the formation of respirable fibers in carbon fiber reinforced plastic materials after combustion

Abstract: Summary Fundamental aspects for the thermal decomposition and formation of respirable fragments of carbon fibers are investigated to assess the health hazard of carbon fiber reinforced plastic material after a fire. The influence of temperature (600°C-900°C)/heat flux (30-80 kW/m2), time of thermal load (up to 20 minutes), and oxygen exposure is analyzed by means of mass loss and fiber diameter of intermediate modulus and high tenacity fibers with initial diameters of 5 to 7 μm. Various types and concentrations of flame retardants were tested with respect to fiber protection. Epoxy-based composite specimens (RTM6/G0939) additionally containing aluminum or magnesium hydroxide and/or zinc borate (1-25 wt% per resin) were analyzed by cone calorimetry. Carbon fiber decomposition increases with combustion/irradiation time and temperature/heat flux, after a threshold temperature (ca 600°C) is exceeded. Critical fiber diameters below 3 μm are reached within minutes and are predominantly observed close to the panel surface in contact with air. Effective fiber protection is achieved by flame retardants acting beyond 600°C, forming thermally resistant layers such as zinc borate. A new field of research is opened identifying flame retardants, which protect carbon fibers in carbon fiber reinforced plastic.

An exploration of enhancing thermal protective clothing performance by incorporating aerogel and phase change materials

Abstract: Summary Thermal liners play a critical role in thermal protective performance for firefighter gear Effective engineering of textile material is necessary to enhance this protective performance A modified thermal protective erformance (TPP) tester was used to study the influence of incorporating aerogel and microencapsulated phase change materials (MPCMs) in thermal liners (including a traditional thermal liner, phase-change layer, and aerogel layer) and the relevant parameters associated with enhanced thermal liner performance Two different phase-transition temperature (45°C and 50°C) of MPCM were selected The samples were exposed to a medium intensity radiation of 15 kW/m2 for 240 seconds, and a skin burn model was applied for second-degree burn prediction Given the selected, results showed that the best TPP in this study was achieved when the phase-transition temperature of MPCM was 45°C and the layering order consisted of the traditional thermal layer (closest to heat source), followed by an aerogel layer, and a final MPCM layer The predicted second-degree burn time was 2183 seconds and increased by 90% compared with only containing traditional thermal liner with a thickness of 5 mm For all 3 materials contained in the thermal liner, the relationship between absorbed energy and predicted second-degree skin burn time indicated that they had a remarkable negative linear correlation (R2 was 09792) The experimental data and predicted results were in good agreement, with a correlation coefficient (R2) of 09911 The findings provide a scientific basis for future textile engineering and a novel approach to improve TPP

Consolidation grouting technology for fire prevention in mined-out areas of working face with large inclined angle and its application

Abstract: Summary The phenomenon of linear flow of slurry in mined-out areas of working face with large inclined angle is a crucial issue that hinders grouting for fire prevention. The traditional way of grouting exerts a poor effect on inhibiting coal spontaneous combustion, so it is in urgent need of a suitable grouting technology for fire prevention in mined-out areas with large inclined angle working face. This paper brings up the consolidation grouting method for fire prevention for the first time and conducts a systematic study on the flow characteristics of slurry and sedimentation characteristics of slurry in mined-out areas with large inclined angle working face. Consolidation slurry materials and their ratio are optimized by experiments. Test platform has been established, and effectiveness of the consolidation grouting for fire prevention has been simulated. The results show that settling velocity of yellow mud increases at first and then decreases as the concentration of consolidation slurry materials ascends. The optimum mass concentration is 0.2%–0.8%. The flow speed of mud is greatly reduced by laying consolidation slurry materials (The decreasing range is approaching 50%). The retention of yellow mud in mined-out areas has significantly increased. Finally, technology in working site has been developed; meanwhile, compressed air and spray between frames have been used during the period of working face, and the consolidated way of expansion bags in wood crib to lay consolidation slurry materials has been adopted during the period of stopping work. Field application shows that CO concentration at upper corner decreases significantly and eliminates signs of spontaneous combustion. Besides, the flowing water becomes clearer, and effectiveness of the consolidation grouting is remarkable after laying consolidation slurry material band. Research results can provide theoretical guidance to technology for fire hazard prevention in mined-out areas with large inclined angle. Copyright © 2016 John Wiley & Sons, Ltd.

A study on fire behaviour of combustible components of two commonly used photovoltaic panels

Abstract: SUMMARY Photovoltaic (PV) modules are installed in some modern buildings for generating renewable energy. When a building catches fire, burning PV panels can contribute to an already very hazardous environment. Two common polycrystalline silicon PV samples A and B were selected with their chemical composition analysed by the Fourier transform infrared spectroscopy with justification by X-ray photoelectron spectroscopy results. Sample A was confirmed to be a silicate product with polyurethane adhesive, and sample B has epoxy resin and is likely to have flame retardant as claimed. Thermal analysis by heating the samples was carried out using thermogravimetric analysis and thermogravimetric analysis coupled with infrared spectroscopy. The fire behaviour was then studied by a cone calorimeter under radiative heat fluxes from 10 to 70 kWm−2. Three key parameters representing flashover propensity, total heat release per unit area and smoke toxicity hazard were obtained from the cone calorimeter tests for ranking the thermal and smoke hazards. The thermal hazards of both PV samples are low, at least during the early stage of a fire without flame acting directly on the sample. However, vast quantities of smoke were emitted from burning PV panels under high heat fluxes.

Thermal properties of polyethylene flame retarded with expandable graphite and intumescent fire retardant additives

Abstract: Summary Low-density polyethylene was flame retarded by combinations of expandable graphite with either ethylenediamine phosphate or 3,5-diaminobenzoic acid phosphate. Cone calorimeter, laser pyrolysis, and open flame exposure tests (supported by video and infrared camera data capture and analysis) were conducted to assess ignition and burn behavior. Cone calorimeter results indicated substantial reductions in the peak heat release rates for all flame-retarded samples but with reduced ignition times and increased flame out times. Smoke generation was suppressed in the presence of expandable graphite. Infrared and video data from open flame fire tests indicated cohesive bonding of expanded strings and thermal shielding properties in all binary systems. All binary systems delivered fire retardation exceeding any of the single fire retardant compounds. They were also able to withstand higher temperatures before ignition, burn through, or sag occurred. All ethylenediamine phosphate-containing binary systems prevented sample burn through, maintaining structural integrity of samples until eventual melting of the polymer media occurred. Thermogravimetric analysis laser pyrolysis results confirmed the good thermal shielding imparted by the intumescent additives. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of zinc borate on flame retardant and thermal properties of polyurethane elastomer composites containing huntite-hydromagnesite mineral

Abstract: Summary The effect of zinc borate (ZnB) was studied on the flame retardant and thermal properties of thermoplastic polyurethane containing huntite-hydromagnesite The flame retardant properties of thermoplastic polyurethane–based composites were investigated using limiting oxygen index, vertical burning test (UL 94), thermogravimetric analysis, and mass loss calorimeter No remarkable effect of ZnB was observed on the flammability properties of composites UL 94 rating did not change regardless of the added amount of ZnB, and the slight increase in limiting oxygen index value was observed at ratio of 1:1 The adjuvant effect of ZnB was observed during the mass loss calorimeter studies by increasing the barrier effect of the residue in the condensed phase and by increasing the formation of incombustible gasses in the gas phase The highest fire performance was achieved at ratio of 1:1

Modelling and Influencing Human Behaviour in Fire

Abstract: Summary The purpose of this article is to present a conceptual model of human behaviour in fire and its impact on egress modelling, life safety analyses and evacuation procedures. This model is based on a theoretical framework of individual decision-making and response to emergencies. From this foundation, the conceptual model is populated with behavioural statements or mini-theories distilled from articles and authoritative reports describing emergency incidents, observations from within the field of evacuation analysis and studies of human behaviour in fire and other emergencies. The conceptual model is intended to guide the egress tool developer, user and practitioner to better account for human behaviour in their respective roles. It is contended that a more credible representation of the evacuee response, that incorporates the behavioural statements described, provides both theoretical and practical advantages. Copyright © 2016 Her Majesty the Queen in Right of Canada. Fire and Materials © 2016 John Wiley & Sons, Ltd.

Flammability of natural plant and animal fibers: a heat release survey

Abstract: Summary With increased interest in sustainable materials for use in building materials and clothing, there is a renewal in the use of natural fibers (plant or animal-based) versus synthetic fibers in a variety of applications. However, there is not as much information available on the flammability of these natural fibers especially when they are used in products where purification techniques used in conventional textile processing are not required. The literature to date suggests that all of the fibers can be grouped into two categories: cellulosic and animal, with the assumption that regardless of original species, the flammability is similar for fibers within each category. In this report, we have conducted a survey via microcombustion calorimetry to determine if all cellulose-based and all protein-based fibers are the same from a heat release perspective. Our findings show that this is not the case, and there are notable differences in fiber types within each genus. Further, how the natural fiber has been treated prior to use can have some dramatic effects on heat release caused by residual impurity content. The results in this paper suggest that there is more to be learned about these natural fiber types in regards to their inherent flammability. Copyright © 2016 John Wiley & Sons, Ltd.

Thermal degradation and fire performance of wood treated with PMUF resin and boron compounds

Abstract: Summary Plantation Chinese fir wood was modified by low molecular weight phenol melamine urea formaldehyde (PMUF) resin, boron compounds (BB), and the mixture of PMUF/BB (PMUF-BB), followed by a curing step. The fire performance and thermal degradation of wood was measured by limiting oxygen index instrument, cone calorimeter, and simultaneous thermal analysis. The results showed that the limiting oxygen index increased to 50.7%, 43.5%, and 55.0% for BB, PMUF, and PMUF-BB samples, respectively. The PMUF resin decreased the heat release rate of wood but increased the total heat release compared with the control samples. The thermal analysis results demonstrated that PMUF resin enhanced the thermal stability of wood, however, had little impact on the residual chars. Combinative treatment with boron compounds could substantially reduce the fire risk for PMUF-modified wood, making them especially useful for application in public settings.

Preparation and studies of new phosphorus-containing diols as potential flame retardants

Abstract: Summary Several new phosphorus-containing potential flame retardants (FRs) were prepared and evaluated for heat release reduction potential, by incorporation of the molecules into polyurethane samples, generated from methylene diphenyl diisocyanate and 1,3-propane diol. The potential FRs were all prepared from commercial diisocyanates, with the phosphorus-containing substructure introduced as a semicarbazone. All of the target structures were diols, to facilitate their incorporation into a polyurethane main chain. The polyurethane samples were prepared via copolymerization, and analysis clearly demonstrated that the potential FRs were chemically incorporated, prior to heat release testing. The heat-release reduction potential of these substances was evaluated using the microcombustion calorimeter. Results demonstrated that both heat release reduction potential and char formation were structure dependent. Some of the compounds containing an aromatic core had more effect on char formation (higher char yields) and peak heat-release rate (lowered heat release) than just phosphorus content alone.

Hexaphenoxycyclotriphosphazene as FR for CFR anionic PA6 via T‐RTM: a study of mechanical and thermal properties

Abstract: Summary The production of carbon fiber reinforced (CFR) anionic polyamide 6 (APA6) plates by thermoplastic resin transfer molding (T-RTM) processing is highly sensitive to the presence of polymer additives such as flame retardants (FRs). However, APA6 is flammable, and therefore, it is mandatory to protect the polymer matrix, especially if the produced materials are intended for aerospace applications. Typically used FR for PA6 cannot be incorporated in the T-RTM processes. With hexaphenoxycyclotriphosphazene, an incorporable and effective FR additive for CFR APA6 was discovered. Cone calorimetry measurements indicate a char formation-based mechanism, and the flame retardancy was further confirmed with limiting oxygen index tests, classification by UL94 (V-0), and FAR25 tests. The influence of this FR on the thermal (thermogravimetric analysis and differential scanning calorimetry) and mechanical behavior (flexural, compressive and ultimate tensile strength, and Charpy impact tests) on CFR APA6 produced via T-RTM processing is evaluated and indicates no interaction with the APA6; it works as a passive filler. Copyright © 2016 John Wiley & Sons, Ltd.

Reaction of aerogel containing ceramic fibre insulation to fire exposure

Abstract: SUMMARY Aerogel containing ceramic fibre insulations represent a newly developed high performance insulation material applied in industrial installations and recently expanding rapidly into the construction industry to reduce the heat transfer through walls and ceilings. As a rather expensive material they are preferentially used in cases where slim layers of insulation are needed mainly in refurbishing of existing buildings especially those under heritage protection. The reaction to elevated temperatures in case of fire is a decisive property for building applications. The present article investigates the reaction to fire of an aerogel containing ceramic fibre insulation already available on the market. This reaction was monitored experimentally by means of temperature sensors at different depth in the material when subjected to the standard ISO fire. The measured temperature evolutions are discussed with respect to radiative heat transfer in an optically thick medium, temperature induced changes in density because of mass loss and the occurrence of endothermic and exothermic reactions detected by thermal analysis and compared with simulation results.

Ascending stair evacuation: walking speed as a function of height

Abstract: There is reason to believe that factors such as physical exertion and behavioural changes will influence the ascending walking speed and ultimately the possibility of satisfactory evacuation. To study these effects, a 2-year research project was initiated with the focus on effects of physical exertion on walking speeds, physiological performance and behaviours during long ascending evacuations. Two sets of experiments on human performance during ascending long stairs, with a height of 48 and 109 m, were performed. The results include aspects such as walking speeds, physical exertion (oxygen consumption, heart rates and electromyography data), perceived exertion and behavioural changes, showing that physical work capacity affects walking speeds in case of long ascending evacuation and should be considered while using long ascending evacuation. Analysis of both walking and vertical speeds is recommended because it provides additional insights on the impact of stair configuration on vertical displacement and the importance of not using the same value for walking speed for different stairs because the design of the stairs has an impact. The novel datasets presented in this paper are deemed to provide useful information for fire safety engineers both for assisting fire safety design as well as the calibration of evacuation modelling tools. (Less)

The effects of coal dust concentrations and particle sizes on the minimum auto‐ignition temperature of a coal dust cloud

Abstract: Summary Flash fires and explosions in areas containing an enriched combustible dust atmosphere are a major safety concern in industrial processing An experimental study was conducted to analyse the effects of atmospheric coal dust particle sizes and concentrations on the minimum auto-ignition temperature (MAIT) of a dust cloud Two different coal samples from Australian coal mines were used The coal dust particles were prepared and sized in 3 ranges, of below 74 μm, 74 to 125 μm and 125 to 212 μm, by using a series of sieves and a sieve shaker A humidifier was used to increase the moisture content of the particles to the required level All the experiments were conducted in accordance with the ASTM E1491-06 method in a calibrated Goldbert-Greenwald furnace The results from this study indicate that coal dust properties, such as the chemical nature (H/C), concentration, particle size (D50), and moisture content, impact on the MAIT For coal dust concentrations less than 1000 gm−3, the MAIT decreases with increasing coal dust concentrations On the other hand, for low concentrations of 100 to 15 gm−3, the MAIT becomes more reliable for particle size D50 rather than for volatile matters

Preparation and characterization of aluminum hypophosphite/reduced graphene oxide hybrid material as a flame retardant additive for PBT

Abstract: Summary Aluminum hypophosphite/reduced graphene oxide (AHP/RGO) hybrid flame retardant with high thermal stability was successfully prepared by a one-step method consisting of the simultaneous reduction of graphene oxide and the deposition of AHP on graphene. The as-prepared sample was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The obtained sample was used as a flame retardant for polybutylene terephthalate, and the flame retardancy of the composites was investigated by a limiting oxygen index test, a UL-94 test, and cone calorimetry. The results showed that AHP/RGO exhibited improved flame retardancy when compared with bare AHP. The addition of AHP/RGO to polybutylene terephthalate led to a significant reduction in the heat release rate and resulted in excellent anti-dripping properties for the composites. Copyright © 2016 John Wiley & Sons, Ltd.

Measurement of self‐heating potential of biomass pellets with isothermal calorimetry

Abstract: In order to assess the risk for spontaneous combustion of biomass pellets during storage it is important to know how prone the fuel is to self-heating, i.e. to determine the reactivity. This artic ...

CFD analysis of smoke backlayering dispersion in tunnel fires with longitudinal ventilation

Abstract: Summary In a longitudinally ventilated tunnel fire, the backlayering flow propagated in the opposite direction to the air current is the most fatal contaminations to users which are blocked upstream of the fire. In the present paper, numerical simulations were conducted using Fire Dynamic Simulator, which is based on large eddy simulations to estimate the backlayering arrival time in a longitudinally ventilated tunnel fire. The effect of a vehicle obstruction on the backlayering arrival time will be also investigated. For this, a vehicle model occupying about 31% of the tunnel cross section is simulated upstream of the fire source with its location relative to the tunnel floor is varied. The numerical investigation shows that the inertia and the buoyancy forces produced by ventilation and fire, respectively, affect the backlayering spread. The backlayering arrival time increases with the longitudinal ventilation velocity while it decreases with the fire heat release rate. When a vehicle obstruction existed within the tunnel, the numerical results show an increase of backlayering arrival time. This increase is significantly more important with the fire distance when the vehicle obstruction approaches the tunnel floor. Two correlations are developed, with and without obstruction in the tunnel, to predict the backlayering arrival time against the distance to fire. Copyright © 2016 John Wiley & Sons, Ltd.

Human behavior in a staircase during a total evacuation drill in a high-rise building

Abstract: Summary Many studies have been conducted on the evacuation behavior on the staircases of buildings, but very little data are available for a situation with many occupants in a crowded high-rise building. Therefore, this study investigated the evacuation behavior of a large number of evacuees on the staircase of a 25-story high-rise building. A total evacuation drill was conducted with 2088 evacuees, and the behavior of 1136 evacuees on the landings of the south staircase was recorded by a video recorder on the ceiling. The relationship between the density and speed of the evacuees on the landings was analyzed from the evacuation data for two situations: without and with merging in the stair flow. The evacuation stair flow in this drill had merging occupants entering from the floors, but no one entered from the lower floors during the latter period of the drill. Therefore, the flow during the latter period was treated as non-merging flow, for which it was observed that, when the staircase was fully crowded, the density on the landings in the moving situation was different from that in the stopped situation. Moreover, the density on the landings was different from that on the treads. Furthermore, in the merging flow, a merging ratio of approximately 50:50 occurred during the congested evacuation. Copyright © 2016 John Wiley & Sons, Ltd.

Development of a screening test based on isothermal calorimetry for determination of self-heating potential of biomass pellets

Abstract: For the risk for spontaneous combustion in storage of biomass pellets to be assessed, it is important to know how prone the fuel is to self-heating. There are traditional methods that are used to d ...

Study of using aluminum hypophosphite as a flame retardant for low-density polyethylene

Abstract: Aluminum hypophosphite (AHP) was first used to improve the flame retardance of low-density polyethylene (LDPE). The flame-retardant properties of LDPE composites were investigated by the limiting oxygen index, vertical burning test (UL-94), microscale combustion calorimetry, and cone calorimeter tests. The results showed that the incorporation of AHP could improve the flame retardancy of LDPE dramatically, the limiting oxygen index of LDPE containing 50 phr AHP reached 27.5%, and the UL-94 could pass V-0 rating. The cone calorimeter test results indicated that PP/AHP composite exhibited superior performance, and the heat release rate and the total heat release of composites were significantly reduced. In addition, the strength of the char was improved with the load of AHP increased. The structure of the char was researched by Fourier transform infrared spectrometry (FTIR) and scanning electron microscope-energy dispersive spectrometer, and the results revealed that AHP promoted the formation of compact char layer. The TG-FTIR analyses proved that AHP could react with LDPE to reduce the production of olefin in gas phase. Moreover, the structure of P–O–C was found, and the effective mechanism of AHP in LDPE composites was also hypothesized in this work.

Improvement of the flame retardancy of plasticized poly(lactic acid) by means of phosphorus-based flame retardant fillers

Abstract: Summary The aim of this study is to improve the flame resistance and toughness of poly(lactic acid) (PLA) with the addition of low amount of flame retardant fillers and plasticizer simultaneously. Poly(ethylene glycol) (PEG) was used as plasticizer for PLA. Ammonium polyphosphate, boron phosphate, and tri-phenyl phosphate (TPP) were used as flame retardant additives. Among these flame retardant additives, boron phosphate was synthesized from its raw materials by using microwave heating technique. Characterization of PLA/PEG-based flame retardant composites was performed by conducting tensile, impact, differential scanning calorimeter, thermal gravimetric analysis, scanning electron microscope, limiting oxygen index, and UL-94 vertical burning tests. Mechanical tests showed that the highest tensile strength, impact strength, and elongation at break values were obtained with the addition of ammonium polyphosphate and TPP into PLA/PEG matrix, respectively. Scanning electron microscopy analysis of the composites exhibited that the more homogeneous filler distribution in the matrix was observed for TPP containing composite. The best flame retardancy performance was also provided by TPP when compared with the other flame retardant additives in the plasticized PLA-based composites.