Statistics of fires in dwellings involving textiles in the United Kingdom

There is widespread concern at present about the fire risk form the use of modern materials in upholstery and other domestic articles. One of the main characteristics of fires in dwellings which start with the ignition of textiles or furniture is that they have a high casualty rate compared with other kinds of domestic fires. Most of the casualties form such fires occur in fires which start in upholstery or bedding, often accidentally ignited by smokers' materials. Asphyxiations by smoke is the commonest cause of death in ‘textile’ and ‘upholstery’ fires. This paper presents relevant statistical information on fires in dwellings attended by local authority fire brigades which result from the ignition of upholstery, bedding, other textiles or furniture and the casualties which these fires cause.     

Measurements of the severity of fires involving private motor vehicles

This paper presents the results of full-scale fires in two private motor vehicles conducted under insturmented calorimeter hoods for the Channel Tunnel Safety Unit, Department of Transport. Measurements of heat release rate, temperatures and other parameters of fire severity are given. The results were used for the assessment of the specification and design of the shuttle wagons and in the subsequent computer modelling calculations to analyse the impact of such a fire within a shuttle wagon. The fires were well ventilated and allowed to develop fully before firefighting intervention. Of the two tests the first burned for 17 min with the gas temperature in the rig reaching 1250°C and with a peak total heat output of at least 7½ MW before being extinguished. The other burned for 57 min, with gas temperatures reaching 1125°C and a pead heat output of 4½ MW.     

Flame lengths under ceilings

The evaluation of hazards from developing room fires often requires a knowledge of flame lengths developed by burning objects. Procedures for estimating flame lengths have been available only for vertical plume fires, where there is no flame impingement on the room ceiling. Calculational procedures are developed for approximate calculation of flame lengths when part of the flame flow is along the ceiling. Four common geometries are treated: unbounded ceiling, plume near corner, plume in corner and one-directional corridor spread. Ceiling flame lengths are calculated by use of the assumption that the total air entrained up to the flame tip is the same for ceiling flow as for the free fire. Comparison with limited experimental data suggests potential for prediction in full-scale room fires.     

Demonstration of the effect of softening and fire resistance of materials on burning characteristics

An important observation during full-scale fires was that burning behaviour is often determined by softening characteristics as well as ignitability, flame spread, etc. Examples include stacking chairs where thermoplastics give a rapid rate of fire growth and suspended ceilings where thermoplastics reduce fire hazard. A test rig has been progressively developed at RAPRA to reproduce the mechanisms and fire growth rates of stacked chairs and to evaluate the role of softening in fire growth. Although the ignitability of fire-retarded materials is less than that of non-fire-retarded grades, the fire growth rate in stacks is similar and may be related to the softening behaviour determined by exposing sheets of material to radiant heat. The rate of fire growth in stacks may be significantly reduced by modifying the softening behaviour of materials, e.g. by using asbestos-reinforced thermoplastics which can form an integral, non-melting felt or by using non-melting materials such as SMC or wood.     

Quantifying wind‐driven firebrand production from roofing assembly combustion

Large outdoor fires present a risk to the built environment. Examples often in the international media reports are wildfires that spread into communities, referred to as wildland‐urban interface (WUI) fires. Other examples are large urban fires including those that have occurred after earthquakes. Firebrands are a key mechanism on how rapidly fires spread in urban fires and WUI fires. An experimental protocol has been developed to ignite full‐scale roofing assemblies and quantify the degree of firebrand production during the combustion process. As wind is an important factor in firebrand generation, the experiments were conducted under a range of wind speeds at the Building Research Institute's Fire Research Wind Tunnel Facility. A further unique aspect of this work is that the experimental results are compared to firebrand size and mass distributions collected from an actual large‐scale urban fire in Japan. Results of these experiments demonstrate that when only oriented strand board is applied as sheathing, a significant number of firebrands collected from roofing assemblies were less than 1 g and 10 cm². It was also observed that experiments on individual building component firebrand generation provided useful insights into actual urban fire firebrand generation.     

Examining the fire risk in London dwellings using the London Fire Brigade Incident database

Analysis of the Fire Brigade's database of fires in London between 2009 and 2020 provided insight into the level of fire safety in the city and how it varies across different types of dwellings and different levels of protection. Regarding the number of fires, fatalities, and injuries, fire safety in London has significantly improved on average over these years. However, average trends cannot analyze catastrophic fires with multiple fatalities, like at Grenfell Tower in 2017, as these events are too rare to form a suitable sample size. Dwelling fires are the most lethal in London: despite accounting for only 28% of fires, they lead to 87% of fatalities and 83% of injuries. The odds of a dwelling fire becoming fatal in London fell from 1 in 174 in 2009 to 1 in 208 in 2019, a decrease of 16%. The total number of fires has decreased over this period, and the number of fires where an alarm was raised has increased, suggesting that the prevention and detection layers of fire safety have improved, while our analysis suggests that the level of protection from the compartmentation and evacuation layers has remained constant over time. An analysis of the different layers of fire protection suggests that compartmentation was the most impactful layer, with a failure in compartmentation increasing the odds of a fire being fatal by 1.5 to 5 times. Overall, this analysis shows that the fire hazard to Londoners in general is low and the lowest since 2009; however, there is still a threat that should not be understated.     

Effect of the nature of fuel on the characteristics of fully developed compartment fires

The coupling between the constituent reactions of a burning process, namely pyrolysis, combustion of volatiles, and (possibly) oxidation of char, is on the whole quite different for fires occurring in the open and for those that develop in an enclosure. Consequently, knowledge of the characteristics of free burning fires is of only limited value in studies related to compartment fire. Since the singe-rout communication between the fire compartment and its environment, always assumed in classical fire studies, is not at all common in real world fires, great sophistication in the mathematical modeling of classical fires is rarely warranted. An examination of pool-like fires and pile fires of noncharring fuels has shown that the severity of such fires in the fire compartment, as characterized by the so-called ‘fire severity product’, decreases slightly with an increase in ventilation. The principal danger presented by these fires, however, is not so much to the fire compartment itself as to the surrounding spaces. An interesting feature of fires involving charring fuels, cellulosies in particular, is that the rate of consumption of fuel, the so-called ‘rate of burning’, is practically independent of all process variables except ventilation. The severity of fires of cellulosics is, as a rule, much higher than that of fires of noncharring fuels. It exhibits a maximum at relatively low ventilations. From the point of view of spread of fire to the surrounding spaces, cellulosics are generally less dangerous than noncharring plastics. Fires involving cellulosics mixed with smaller amounts of noncharring plastics can be characterized as basically cellulosics fires, with a superimposed initial period of very high spread liability.     

Experimental study on heat release rate measurement in tunnel fires

Knowledge about the heat release rate (HRR) is essential for studying tunnel fires. The standard method in ISO 9705 is widely applied to calculate the HRR of combustion by measuring the consumption of oxygen in a fire. However, the studies of HRR measurement in full‐scale tunnel fires are rare because of the complication and costs of large experiments. This paper presents a system based on the principle of oxygen consumption calorimetry for the measurement of HRR and total heat release (THR) of full‐scale fires in tunnels. A total of 22 fire experiments are performed in a large‐scale ventilated testing metro tunnel with dimension of 100.0 m × 5.5 m × 5.5 m to validate the reliability and effectiveness of this system. Firstly, four oil spray fire tests are conducted with nozzle flow of 106 L/h at (1 ± 0.1) MW HRR to calibrate the instrumentation. Then, 18 full‐scale fire tests using square diesel pools at five sizes (0.5, 1.0, 2.5, and 5.0 m²) and wood cribs as fire sources are carried out for the measurement of HRR and THR. Results provided by the comparison between the measured HRR and THR values of the fire tests and the theoretically calculated ones show that our system works effectively in the HRR measurement of full‐scale fires in tunnels.     

Post-Flashover compartment fires

Fourteen mathematical models of post-flashover compartment fires are classified on the basis of fourteen principal modeling aspects. Expressions are presented for the potential of fire to spread by destruction and convection. The assessment of the fire resistance requirements for the compartment boundaries is discussed and measures to counter the potential of fires to spread by convection are outlined.     

Soft furnishing fires: They're still a problem

Home fires in which soft furnishings were first ignited or contributed to fire spread cause a disproportionate share of US home fire deaths. Although the death toll from these fires is much lower than in the 1980s, the rate of death per 1000 reported fires has doubled. Data from the National Fire Incident Reporting System and the National Fire Protection Association's annual Fire Experience Survey were used to create national estimates of these fires and casualties. Including both fires in which upholstered furniture was the item first ignited and contributed most to fire spread, in 2013‐2017, upholstered furniture was involved in an estimated average of 7120 (2%) home fires per year, resulting in an average of 570 (22%) deaths per year. Mattresses or bedding were involved in estimated average of 10 530 (3%) home fires per year, resulting in an average of 370 (14%) deaths annually. In most of these fires and deaths, the item was first ignited. Smoking materials were the leading cause of these fires (20%‐26%) and associated deaths (52%‐54%). Various types of operating equipment and small open flames also play a role. Understanding the causes of these fires is essential to develop new strategies to prevent them.     

Fire resistance of cold-formed steel framed shear walls under various fire scenarios

This paper presents results of large-scale experiments with varying levels of fire severity on lateral force-resisting systems commonly used in cold-formed steel framed buildings. Gypsum-sheet steel composite panel sheathed walls, oriented strand board sheathed walls, and steel strap-braced walls are examined. Postflashover fire conditions of two different intensities as well as 1 hour of fire exposure similar to that in a standard furnace qualification test are studied. Additionally, a full-scale furnished kitchen fire experiment is conducted for comparison. The results highlight differences in the thermal response and subsequent performance of the walls as well as differing sensitives of the walls to pre-damage, eg, that might occur during an earthquake. The results are part of a larger effort to provide fragilities for these wall systems in response to realistic fires for performance-based design.     

Design of Light Steel-framed Walls for Fire Resistance

Light steel-frame building systems are becoming more prevalent in commercial, industrial and residential construction in New Zealand. Tested fire resistance ratings are generally available for non-load-bearing systems, but not for load-bearing applications. This study investigates the performance of load-bearing light steel-frame systems exposed to fire. Methods are presented for calculating the reduction of steel strength and stiffness at elevated temperatures, and for predicting the deflections resulting from temperature gradients and P-Δ effects. Heat transfer modelling by computer is used to predict steel framing temperatures for systems exposed to the standard ISO 834 time–temperature curve and real fires. Three full-scale furnace tests were carried out to evaluate analytical predictions. A design procedure is proposed.     

A comparative study of test methods for assessment of fire safety performance of bus interior materials

This work concerns the assessment of fire performance of interior materials in buses. The widely used test method ISO 3795/FMVSS 302 has received much criticism mainly based on the fact that the test is a small‐scale method not suited for bus fires induced by for example fire in the engine compartment or fire in a tyre. Furthermore, test specimens are oriented horizontally, whereas much fire spread in a real bus fire occurs on vertically oriented products. Seventeen products were investigated: 11 textiles, four solids and two insulations. Three test methods were compared: ISO 3795, ISO 6941 and ISO 5658‐2. Given the existing criteria for interior materials, it was found that ISO 6941 and ISO 5658‐2 place harder requirements on the materials. When the three methods were compared, it was found that ISO 3795/FMVSS 302 and ISO 6941 are insufficient for simulating bus fires typically occurring today. Such fires are often initiated by a fire in the engine compartment or in a tyre and can hardly be simulated by small‐scale methods as ISO 3795/FMVSS 302 or ISO 6941 even if the ISO 6941 method to some extent gives results similar to the established large‐scale ISO 5658‐2 method. Copyright © 2011 John Wiley & Sons, Ltd.     

Computational fluid dynamics modelling of hydrocarbon fires in open environments: Literature review

Hydrocarbon fuels are involved in most major fire accidents occurring in industrial facilities. Due to the need for an in-depth understanding of the phenomena associated with hydrocarbon fires, computational fluid dynamics (CFD) modelling has been widely employed in the field of fire risk analysis over the last decades. The aim of the present review is to provide the reader with a comprehensive compilation and discussion of the most important aspects involving CFD modelling to simulate hydrocarbon fires in open environments. The fire sizes simulated, the fuels used, the codes employed, the variables of interest measured, the simulation purposes and the results accuracy have been examined through a wide literature survey, which includes peer-reviewed journals and congress papers dating from the 90s until now.     

Poly(vinyl chloride) and its fire properties

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.     

Effect of Melting Behaviour on Upward Flame Spread of Thermoplastics

The effect of melting behaviour on upward flame spread of thermoplastic materials when subjected to small ignition sources and considered to suffer no external flux was studied using large-scale tests. For moderate fire conditions the cone calorimeter was utilized, with the sample set in a vertical orientation to study the melting behaviour of the specimens. Under these conditions the results indicate that the melting behaviour significantly affects upward flame spread behaviour. A pool of the melt which formed at the base of the vertically oriented sample tested creates a pool fire which then controls the fire growth and flame spread. In contrast, it was found that some thermoplastic materials which have higher glass transition temperatures or undergo a special pyrolysis process such as depolymerization, intumescing or charring do not experience significant melting behaviour when exposed to the same thermal insult. As a result, they behave very differently in terms of upward flame spread. The study also indicates that the melting behaviour of thermoplastic materials is an important characteristic in fires which should be taken into account in the development of modelling, in particular for upward flame spread models. © 1997 by John Wiley & Sons, Ltd.     

Fire spread from an open‐doors electrical cabinet to neighboring targets in a confined and mechanically ventilated facility

Electrical cabinet fire is one of the main fire hazards in nuclear power plants. As part of the OECD PRISME‐2 programme, four fire tests were carried out to investigate the fire spread from an open‐doors electrical cabinet to overhead cable trays and adjacent cabinets in a confined and mechanically ventilated facility. These tests, named CFS‐5 to CFS‐7 and CORE‐6, used same both cabinet (fire source) and three overhead cable trays. The trays were filled with a halogenated flame‐retardant cable‐type for CFS‐5 and one halogen‐free for the three other tests. Moreover, fire dampers were used for CFS‐7 test while CORE‐6 test implemented two additional cabinets adjacent to the fire source. Measurements such as flame and gas temperature, gas concentration, mass loss rate, and heat release rate were performed for investigating the fire spread. Cabinet fire spread to the cable trays for CFS‐5 and CFS‐6 tests. Three fast and short cable tray fires were shown for CFS‐5, while a slow and long cable tray fire was highlighted for CFS‐6. In contrast, the fire dampers shutdown for CFS‐7 test prevented ignition of the overhead cables. Furthermore, for CORE‐6 test, cabinet fire spread to the adjacent cabinets, but the upper cables were not ignited.     

Characterization of the fire environments in central offices of the telecommunications industry

Eight free burning and two sprinklered fire tests were performed with electrical cable trays and live digital switch racks in a large enclosure to simulate telecommunications central office (TCO) fires started by electrical overheating. Very‐slow‐growing (non‐flaming), slower‐growing (partially flaming) and low‐intensity‐faster‐growing (flaming) fires releasing gray‐white, gray, and black smoke, respectively, were observed in the tests. Under quiescent conditions present in the unvented enclosure fire tests for cables, very‐slow‐growing fires were detected in about 1452 s, whereas the slower‐growing fires were detected in about 222 s by commercial fire detectors. Under ventilation conditions typical of TCOs, detection times were very similar for the five types of commercial TCOs fire detectors used in the tests. The average detection times for slower‐growing fires (cable fires) and low‐intensity‐faster‐growing fires (digital switch rack fires) were 242±17% and 249±11%s respectively. The TCO procedures to reduce smoke damage from fires (on fire detection, inlet ventilation flow is turned off and exhaust flow is turned on) were found to be beneficial. The extent of smoke damage decreased significantly with an increase in the exhaust flow rate. The chloride ion mass deposition suggested that equipment recovery would be possible in the smoke environment if the cable vapor concentration could be reduced below about 3 g/m³. The metal corrosion rate was found proportional to the 0.6th power of the smoke concentration, similar to that found for the corrosion of metal surfaces exposed to aqueous solutions of HCl and HNO₃ and for acid rain with no protective layer at the surface. Sprinkler water was found to wash down the smoke deposits on the surfaces with little indication of corrosion enhancement. Copyright © 2003 John Wiley & Sons, Ltd.     

Experimental study of the burning behavior of n‐heptane pool fires at high altitude

The same configured calorimeters were built in Hefei (99.8 kPa) and Lhasa (66.5 kPa), respectively. Four sizes of round pans with diameters of 10, 15, 20, and 25 cm were adopted to study the effect of high altitude on the burning behavior of liquid pool fires. Analysis on the burning rate obtained in this study and in the literature at different altitudes indicates that pressure fire modeling performs better than radiation fire modeling in correlating the burning intensity (burning rate per unit area) with pressure and pool diameter for cases under low ambient pressure. The study also shows that heat release rate and combustion efficiency decrease at higher altitude. For medium pool fires, the burning intensity and heat release rate are proportional to D^5/2, thus the combustion efficiency being independent on pool sizes but decreases at higher altitude by a factor approximate to the pressure ratio. Copyright © 2014 John Wiley & Sons, Ltd.     

Cable tray FIRE tests simulations in open atmosphere and in confined and mechanically ventilated compartments with the CALIF3S/ISIS CFD software

Fire hazard in nuclear power plants (NPPs) is particularly often investigated as potential cause of safety equipment failure and confinement loss. Many fire events recorded in NPPs involve electric cables, widely used throughout facilities. IRSN is developing the CALIF3S/ISIS computational fluid dynamics software devoted to fire simulation in large‐scale confined and mechanically ventilated compartments. This paper presents two aspects of the CALIF3S/ISIS code ability to simulate fires. The first one concerns vertical and horizontal spreading of a cable tray fire in open atmosphere using an approach based on the FLASH‐CAT cable fire spread model. Resorting to the suitable parameters of the FLASH‐CAT model based on video fire analyses of tests enables to properly compute the heat release rate of the fire. The second aspect concerns the ability to simulate the evolution and consequences of fires in confined and mechanically ventilated compartments. For these cases, the heat release rate measured during the corresponding experiment is used as input data for the calculations. The predicted evolutions of pressure or gas temperatures are in relatively good accordance with the experiments. The major discrepancy concerns gas concentrations in the fire room which is attributed to a lack of information about the properties of the fuel material.