Experimental study on tire fire penetration into a motorcoach passenger compartment

Two full‐scale fire experiments were conducted to determine the mode of penetration of a tire fire into the passenger compartment of a motorcoach. A special burner was designed to imitate the frictional heating of hub and wheel metal caused by failed axle bearings, locked brakes, or dragged blown tires. For the first experiment, heating to obtain tire ignition was initiated on the exterior of the passenger side tag axle wheel and for the second, on the exterior of the passenger side drive axle wheel. Measurements of interior and exterior temperatures, interior heat flux, and heat release rate were performed. Standard and infrared videos and still photographs were recorded. Both experiments showed that the tire fires ignited the plastic fender and glass‐reinforced plastic exterior side panel (below the windows) upon which the fires spread quickly and penetrated the passenger compartment by breaking the windows. Measurements showed that other potential fire penetration routes (flooring and lavatory) lagged far behind the windows in heating and degradation. Copyright © 2012 John Wiley & Sons, Ltd.     

A new test methodology for studying the response of walls to real fire environments

A new test methodology was developed to investigate the response of walls, partitions, and in-wall systems exposed to real fires. The apparatus includes a 3.5 m long, 2.3 m wide, and 2.3 m high fire compartment within a standard sea container. A wall specimen measuring up to 1.8 m wide, 1.8 m tall, and 0.3 m deep is mounted in a steel frame at one end of the fire compartment. Fire exposures to the wall specimen evolve over time depending on the fuel load and ventilation configuration. Gas temperatures and heat flux were characterized for five different fuel and ventilation configurations. Peak exposures ranged from 30 to 75 kW/m² for about 20 minutes. Five additional tests were conducted using a single fuel and ventilation configuration to assess the repeatability of the test methodology. It was found that a 19.3 minute growth period occurred plateauing at a ceiling temperature of 708°C for 8.4 minutes, on average. Compartment gas temperatures were found to be repeatable, having a sample standard deviation less than 32°C for symmetric data. Repeatability improved when account was taken for the rapid fire growth inflection point. The utility of the approach for studying fire performance of building elements was demonstrated.     

Experimental study on hardening a motorcoach against tire fire penetration

Three full‐scale fire experiments were conducted to assess methods of hardening the motorcoach against penetration of a tire fire. The first method was to replace the combustible fender and exterior side panel above the wheels with stainless steel sheet metal. The second method was to coat the plastic fender and side panel with an intumescent layer. The third method was to install a sheet steel fire plume deflector between the fender and side panel. A special burner was used that imitates the frictional heating of hub and wheel metal caused by failed axle bearings, locked brakes, or dragged blown tires. For each experiment, heating to obtain tire ignition was initiated on the exterior of the passenger side tag axle wheel. Measurements of interior and exterior temperatures, interior heat flux, and heat release rate were performed. Standard and infrared videos and still photographs were recorded. The experimental results were compared with those obtained with no fire hardening. The metal replacement method performed best and prevented fire penetration for over 30 min longer than the nonhardened cases. The intumescent coating extended fire penetration by about 20 min longer than the nonhardened cases. The steel plume deflector had no significant impact on the timing for fire penetration of the windows. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.     

Performance of a light timber‐framed compartment in natural fire subjected to lateral load

A common approach for designing buildings for lateral stability during and post‐fire in New Zealand is to ensure that a fire‐rated structure does not collapse when subjected to a nominal horizontal force. For external walls of residential buildings, which are required to resist a lateral load of 0.5 kPa, it is hypothesised that the adjacent unrated construction could provide sufficient support. A natural fire experiment has been conducted to evaluate the fire performance of a laterally loaded light timber‐framed compartment, with external dimensions of 4.33 m × 3.35 m and a stud height of 2.4 m constructed with a timber truss roof and plasterboard ceiling. During the experiment, the ceiling collapsed at 12 to 13 minutes, and the bottom chord of the roof truss failed in tension after 28 minutes which resulted in the fire‐rated wall losing its lateral stability at 28 minutes. The fire severity experienced in the compartment has been estimated to correspond to an equivalent time of 33‐minute exposure to a standard furnace time‐temperature. It is concluded that there is no need to provide nominal (additional) moment‐resisting fixity at the base of the fire‐rated wall when exposed to the standard fire for no more than 30 minutes.     

Heat release rate and computer fire modelling vs real‐scale fire tests in passenger trains

The materials and products used in passenger trains may not be the first ignited element, but during the fire development, these materials, especially ceiling linings and wall coverings, contribute significantly to the fire growth. The fire safety requirements in passenger trains consist mainly of bench‐scale tests, with particular focus on the sample geometry, position and fire exposition. When this information is extrapolated to real end use conditions limitations appear. In this paper, a discussion of the use of fire dynamics simulator model and heat release rate experiments in cone calorimeter (bench‐scale test) is presented in order to represent the fire development in a passenger train compartment. For the study, two fire scenarios were selected: (1) the single burning item SBI test (modified) and (2) a passenger train compartment. Initially, the limitations of the assumptions and hypothesis made when producing the model were analyzed and the research team carried out a sensitivity study of the model results considering different grid sizes. In order to validate the model, both bench‐ and full‐scale fire tests were considered based on the results provided by the European research program FIRESTARR. The limitations and uncertainties in the results demonstrate the importance of two basic factors: the incident heat flux in the cone calorimeter tests and the prescribed ignition temperature. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal effect on surrounding combustibles in minivan passenger car fires

In the fire safety design of parking lots and buildings, estimating the possibility of fire spreading to surrounding combustibles, such as neighboring buildings and cars, is essential. The ignition possibility to surrounding combustibles can be predicted from the heat flux from a burning car to the combustibles. In this study, we conducted 2 full‐scale car fire experiments using minivan passenger cars and measured the heat fluxes to their surroundings. The cars were ignited at the rear bumper with 80 g of alcohol gel fuel. The windows were closed. Heat flux gauges were placed around the car to measure the heat flux in various directions. Cedar boards were placed next to the gauges, and burn damage to the boards was observed. When the windows shattered in succession, combustion in the passenger compartment became larger. At a distance of 50 cm from the burning car, the heat flux was greater than 40 kW/m², and most of the cedar boards were completely burned. At a distance of 1 m, the heat flux was 10 to 20 kW/m², and some of the cedar boards were burned. We devised a method for modeling the shape and temperature of flames in the burning cars. Furthermore, we propose a method for calculating heat fluxes in the lateral direction of the burning minivan passenger car, and we compared the calculated and measured heat fluxes as a means of verifying the proposed method. The shape of flame in the burning car was approximated as a rectangular prism to calculate the heat flux. The calculation results were in good agreement with the experimental results. The proposed method is expected to be useful for fire safety engineering.     

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 fire compartment with door opening and roof opening

A series of reduced‐scale experimental fires was conducted to study the characteristics of fire induced vent flows in a reduced‐scale post‐flashover fire compartment with a door opening and a roof opening. The fire source was a heptane pool fire near the wall furthest from the door vent. In the study, the roof vent opening area was systematically varied between experiments and the characteristics of vent flows through the door opening are presented as a function of the roof vent opening area. The experimental results show that the mass flow rate of air into the compartment increases linearly as the size of roof vent opening increases. Analytical vent flow calculations based on the hydrostatic pressure difference between two quiescent environments are presented for a post‐flashover fire compartment with both horizontal and vertical openings. The calculated results are in good agreement with the experimental measurements. Copyright © 2005 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 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.     

Experimental study of fire growth and ejected plume in a cross‐ventilation compartment under wind condition

In this study, a set of reduced‐scale experiments were conducted to study the influence of external wind on the fire growth and ejected plume in a compartment with two openings. The approaching wind velocity was set as 1.5 and 3.0 m/s, respectively. The temperatures in the fire compartment were also measured by thermocouple matrixes. The images of the projected flames from the opening and the fuel mass loss rate were recorded by digital video and electronic balance, respectively. It is observed that the wind with velocity of 1.5 m/s can reduce the combustion severity by decreasing the ventilation in the fire room and enhance the duration time of combustion. On the contrary, the wind with velocity of 3 m/s can promote the combustion severity by increasing the ventilation in the fire room and reduce the duration time of combustion. The theoretical analysis shows how the external wind that coupled with the thermal buoyance influence the ventilation of the compartment, and a critical velocity or a dimensional number are suggested to predict the ventilation of the fire room, which is believed to influence the compartment fire behavior greatly.     

Performance of a non‐load‐bearing steel stud gypsum board wall assembly: Experiments and modelling

A gypsum wall assembly was exposed to an intense real‐scale compartment fire. For the wall assembly, temperatures were measured at the exposed face, within the stud cavity, and at the unexposed face during the fire exposure. Total heat flux gauges were used to measure the temporal variation of the energy incident on the walls, and cameras, both visual and infrared, were used to image the unexposed face of the wall assembly during the fire exposure. The behaviour of the wall assembly under the fire load is discussed as are current model results for a simulation of the fire test. Copyright © 2006 John Wiley & Sons, Ltd.     

Incident heat flux measurements in floor and wall furnaces of different sizes

This paper presents the results of incident heat flux experiments in standard (full‐scale) and non‐standard (intermediate‐scale) wall and floor fire resistance furnaces. These experiments were conducted to investigate the effects of full‐scale furnace depth (wall and floor furnaces), furnace size (full‐ and intermediate‐scale furnaces) and intermediate‐scale furnace orientation (vertical and horizontal positions) on the incident heat flux in fire resistance test furnaces. Copyright © 2005 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

Crack evolution process of window glass under radiant heating

Window glass breakage has a significant impact on the compartment fire development being sometimes a weak link for fire safety design. This work focuses on the process of crack evolution of window glass in a fire environment. A total of 11 experiments were conducted in a box apparatus by changing heating rate of a heat source. The box apparatus is an enclosed compartment, which includes the heat source, assembled boxes, and glass pane. Crack time, temperature field, breaking stress, crack evolution, and fall‐out of the glass panes are presented. Main and secondary fractures are defined and illustrated in the process of crack evolution. Average time to the first, second, and third main fractures decreased as the heating rate of heat source increased. The average breaking stress was 71.14 MPa for float glass at the time of first main fracture. The crack evolution process was very complicated. Cracks initiated at an edge and propagated towards other edges for main fractures. Multiple cracks were joined together to form cracked glass islands. The fall‐out of cracked glass islands under radiant heating was more difficult than that under real fire scenarios.     

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.     

Investigation of a combustible material in the fire of Hengyang merchant's building

Agaric, a kind of important combustible material in the fire of Hengyang merchant's building, was investigated using different experiment equipments. Its degradation and pyrolysis behavior were studied by means of thermogravimetric and kinetic analysis and pyrolysis gas chromatography–mass spectroscopy analysis. External radiation heat and internal heat were used to ignite the agaric. For external radiation ignition, a series of bench‐scale fire tests were done in cone calorimeter in accordance with ISO 5660. As for the internal heat ignition, a fire test was carried out in a full‐scale room in accordance with ISO 9705. Multi‐parameter measurement, including heat release rate (HRR), mass loss rate (MLR), temperature field and species concentration, has been accomplished. Meanwhile, the process of a full‐scale fire test was numerically simulated. The computational results were consistent with experiment data, which will lay down a good foundation for further study in fire reconstruction of the whole fire. Copyright © 2008 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.     

Experimental study on fire properties of interior materials used in low‐floor light‐rail trains

In this work, cone calorimeter tests were conducted to investigate fire properties of interior materials (floor covering [FC], aluminum plate covered with paint [APCP], light diffuser [LD], and gel coat [GC]) used in low‐floor light‐rail trains. Ignition time (t_ig) of each material decreases with the increase of radiative heat flux. The decreasing order of the four samples by ignition time under the same radiative heat flux is LD > APCP > FC > GC. The heat release rate (HRR), peak value of HRR (PHRR), time from ignition to PHRR (t_p), fire growth rate index (FIGRA), and fire growth index (FGI) rise with the increasing radiative heat flux. For the FC, LD, and GC, single HRR peak is observed in the HRR history while three peaks are observed for APCP. For PHRR, LD > FC > APCP > GC, while for t_p, GC < FC < APCP < LD. Under most conditions, the FIGRA and FGI of the FC is the highest among the four materials. Results of this work are beneficial to evaluate fire hazard of low‐floor light‐rail train and determine the emphasis of fire prevention.     

Evaluation of thermal fire hazard of 10 polymeric building materials and proposing a classification method based on cone calorimeter results

The use of polymeric building materials has been grown in many countries of Middle East in recent years. However, there are only a few fire testing laboratories in this region. Therefore, development of a method for controlling the reaction to fire of materials with bench scale tests is necessary. Providing a framework for classification of thermal fire hazard of materials based on bench scale heat release rate results was attempted. The fire behavior of 10 polymeric building materials was tested with cone calorimeter. The relationship between reaction to fire variables and physical properties of tested samples was examined. The thermal fire hazards of materials were assessed using methods presented by different researchers and with Conetools software. The results revealed that time to ignition, peak rate of heat release, and total heat release are essential variables for determining the fire hazard of materials. A classification method is proposed, which can be used in building codes in countries where the full‐scale test facilities are not available. The method also can be used for quality control purpose and evaluation of fire behavior of materials in bench scale by manufacturers. An example of potential requirements for interior finishes for some occupancy types is also presented. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental investigation on smoke spread characteristics and smoke layer height in tunnels

A series of experiments were carried out in a model‐scale tunnel with dimension of 6.0 m × 1.0 m × 0.7 m to investigate the smoke spread behaviors and the typical smoke layer height. Alcohol was employed as fuel, and the heat release rate was set to be 9.5, 18.4, 30.1, and 63.5 kW, respectively. The temperature profile in the tunnel was measured, and the buoyant flow stratification conditions were visualized by a laser sheet. The experiment results show that the N percentage rule would greatly influence by subjective factors. As the N (10, 20, 30) value increases, the smoke layer height also increases. The results calculated by the buoyancy frequency method were more accurate. Fan's prediction method (Fan WC, Wang QG, Jiang FH. Concise Guide of Fire Science. He Fei: University of Science and Technology of China Press; 1995.161 p.) does not accurately evaluate the smoke layer thickness in tunnel fire. An enhanced empirical formula for predicting the smoke layer thickness in the one‐dimensional horizontal spread stage was proposed. It is shown that the empirical formula could well predict the smoke layer thickness by comparing with the experimental data of previous studies.