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.     

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.     

PV electrical plants fire risk assessment and mitigation according to the Italian national fire services guidelines

Photovoltaic (PV) systems design and construction are generally focused on efficiency and reliability, in order to increase the amount of solar energy that can be converted into electrical energy. Therefore, in a PV electrical generation plant, fire risk is not taken into account by technical designers and, furthermore, is not considered by constructors of PV plant installation. This paper shows a procedure to assess and mitigate the fire risk as a result of a PV plant installation located over buildings, according to the Italian National Fire Services Guidelines. Firstly, an introduction to the main faulty modes of PV arrays and modules is reported in order to highlight how the pre‐existing level of fire risk is increased for a building or construction work where a PV electrical generation plant is installed. Hence, the paper explains how the guidelines point out fire risk assessment steps oriented to PV plant installation over buildings. In addition, the guidelines contain some useful fire risk mitigation technical solutions. The guidelines have been developed with safety as their main objective. The PV sector has been presented with certain limitations in roof or façade installations as a result of PV fire ignition characteristics and firefighting suppression techniques. The aim of the guidelines is to provide the solar PV industry with information and technical arrangements to aid the design, construction and installation of solar PV systems meeting the objectives of both solar PV industry and fire safety requirements. Copyright © 2014 John Wiley & Sons, Ltd.     

Quantitative fire risk assessment of cotton storage and a criticality analysis of risk control strategies

Although fires can easily occur during cotton storage, research on cotton storage fire risk assessment is limited. This work focuses on cotton storage fire risk assessment and investigates the criticality of risk control strategies. Bow-tie and Bayesian network models are established to investigate the relationships among accident causes, safety barriers, and possible consequences. The results show that the first safety barrier (detection and extinguishment before fire brigade arrival) is more controllable and more effective than the second safety barrier (fire brigade). Based on the collected probability data, the probability and risk of a common accident are higher than those of a large accident and severe accident when safety barriers succeed; when the first safety barrier fails, the probabilities and risks of large and severe accidents increase by more than 2000 times. The criticality of safety measures is investigated by analysing their structural importance, probability importance, and critical importance. The critical events for fire occurrence are an open flame and sparks during storage, and the critical events for detection and extinguishment before fire brigade arrival are watchkeeper monitoring, regular patrolling, and automatic fire alarm systems. For cotton storage safety, this work and its outcomes are used to support the decision-making of fire risk prevention and control.     

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.     

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.     

An experimental investigation on char pattern and depth at postflashover compartments using medium‐density fibreboard (MDF)

To determine the fire origins for postflashover compartments, the char pattern and depth are investigated. A set of experiments was carried out using large‐scale compartments made of medium‐density fibreboard. A liquefied petroleum gas burner was used as the ignition source to mimic the fire origin. The burner was set at different locations in different experiments. It is found that time to flashover, intermittent flame of gas burner and ventilation condition have effects on the char patterns. The ‘ventilation patterns’ are likely to confuse the fire investigators; therefore, it needs to be identified from the ‘flame patterns’. In general, the ventilation patterns at the floor would initiate directly from the compartment opening. CFD simulations is used to reflect the ventilation conditions during fires thus assisting the identification of ventilation patterns. For those cases with less distinguishable char patterns, the profiles of total leftover material thickness and char depth were used to determine the fire origin. The char layer and total thickness in the flame regions were found to be respectively deeper and thinner than the rest parts of the compartment. The ventilation condition also affects the char depth profile; therefore, it cannot be ignored from analysis. At the end, a strategy of fire origin determination is proposed. Copyright © 2014 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.     

湿法煤气化厂房的火灾危险性及其防火防爆措施分析

针对湿法煤气化工艺的特点,分析了水煤浆、高压纯氧及粗煤气等物料的火灾危险性,讨论了煤气化厂房在生产中的火灾危险因素,计算了粗煤气泄漏后发生爆炸或形成喷射火时的影响范围,提出了湿法煤气化厂房所应采取的控制点火源、防止产生爆炸性混合气体、及时发现和处理事故等防火防爆措施,以及寒冷地区封闭的煤气化厂房所应采取的泄压及通风措施。     

Experimental studies on characteristics of fire whirl in a vertical shaft

An internal fire whirl can be generated readily in a tall shaft model with appropriate gap width at one corner. Experimental study was carried out to investigate the relationship between the characteristics of an IFW and the corner gap width in a 9‐m‐tall vertical shaft model. The vertical shaft had a 2.1 m by 2.1 m square section with gasoline pool fire of different diameters burning inside. The gap width was varied to investigate its impact on fire whirl characteristics, such as flame development, swirling intensity, flame height, flame temperature, and heat release rate of the gasoline pool fire. Vigorous flame swirling motions were generated when the ratio of the gap width to the shaft section perimeter was within the range 0.16 to 0.21. From the flame streamline angle, it was observed that the swirling component was much stronger than buoyancy component near the bottom of burning region. The swirling component decreased and became roughly the same as buoyancy near the middle. Finally, it diminished to being much weaker than buoyancy near the top of the fire. These observations suggest that the Froude number Fr decreased from a large number to 1, and then continued to decrease to 0.     

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.     

Fire‐retarding properties of nanowollastonite in particleboard

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

Reconstruction of the Grenfell Tower fire – Part 4: Contribution to the understanding of fire propagation and behaviour during horizontal fire spread

The tragic events at Grenfell Tower in 2017, involving a combustible façade system, have raised concerns regarding the fire risk that these systems pose. In this series of articles, so far published, fire development inside the initial apartment has been investigated using an appropriate computational fluid dynamics (CFD) model. Several scenarios including different fire sources and ventilation conditions were addressed. Fire propagation through the window to the external façade and to higher apartments was modelled. This model was validated by comparing the numerical results with the visual observations reported in the Grenfell Inquiry. A CFD model of the complete east face of the Grenfell Tower was then created. This paper details CFD modelling of the complete Grenfell Tower façade during the late horizontal phase of fire spread. As the physics of lateral flame spread is different from that for upward flame spread, it is important to assess the validity of the model, thus far developed, for this configuration. Fire propagation over the whole façade is modelled and compared with observations from the real disaster. This provides a better understanding of its fire behaviour and of the contribution of architectural details and their impact on fire spread.     

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.     

Flame extension and the near field under the ceiling for travelling fires inside large compartments

Structures need to be designed to maintain their stability in the event of a fire. The travelling fire methodology (TFM) defines the thermal boundary condition for structural design of large compartments of fires that do not flashover, considering near field and far field regions. TFM assumes a near field temperature of 1200°C, where the flame is impinging on the ceiling without any extension and gives the temperature of the hot gases in the far field from Alpert correlations. This paper revisits the near field assumptions of the TFM and, for the first time, includes horizontal flame extension under the ceiling, which affects the heating exposure of the structural members thus their load-bearing capacity. It also formulates the thermal boundary condition in terms of heat flux rather than in terms of temperature as it is used in TFM, which allows for a more formal treatment of heat transfer. The Hasemi, Wakamatsu, and Lattimer models of heat flux from flame are investigated for the near field. The methodology is applied to an open-plan generic office compartment with a floor area of 960 m² and 3.60 m high with concrete and with protected and unprotected steel structural members. The near field length with flame extension (fTFM) is found to be between 1.5 and 6.5 times longer than without flame extension. The duration of the exposure to peak heat flux depends on the flame length, which is 53 min for fTFM compared with 17 min for TFM, in the case of a slow 5% floor area fire. The peak heat flux is from 112 to 236 kW/m² for the majority of fire sizes using the Wakamatsu model and from 80 to 120 kW/m² for the Hasemi and Lattimer models, compared with 215 to 228 kW/m² for TFM. The results show that for all cases, TFM results in higher structural temperatures compared with different fTFM models (600°C for concrete rebar and 800°C for protected steel beam), except for the Wakamatsu model that for small fires, leads to approximately 20% higher temperatures than TFM. These findings mitigate the uncertainty around the TFM near field model and confirm that it is conservative for calculation of the thermal load on structures. This study contributes to the creation of design tools for better structural fire engineering.     

Smart firefighting construction in China: Status,problems, and reflections

“Smart firefighting” construction as a part of the “smart city” has been a concern of the public security and fire agencies at all levels. In this study, the status, problems, and reflections of “smart firefighting” construction in China are discussed. A recent survey indicates that China has launched its smart firefighting construction and initially created a new perspective on its regional smart firefighting work based on three main aspects: intelligent disaster perception by Internet of Things (IoT) construction, intelligent disaster prevention by big data construction, and intelligent disaster disposal by emergency rescue platform construction. However, the current smart firefighting construction in China still has some prominent problems such as the data interconnectivity and normalized management of various platforms, the extensibility of smart firefighting platforms, and the intelligent level of smart firefighting researches, which need to be solved urgently. Therefore, we argue that smart firefighting construction in China should establish data interconnectivity, industrial normalized management, 2D/3D geographic information interaction and extension, high-integration fire protection theory, and many other aspects in the near future and truly realize firefighting visualization and efficient data applications for 4D time space. This study could provide valuable reference for smart firefighting and smart city construction.     

Sodium‐based fire resistant geopolymer for passive fire protection

This paper primarily deals with the examination of the performance under thermal loading of a fire resistant sodium‐based geopolymer from Ferronickel slag. In addition, the mechanical, physical and thermal properties of material and their respective variation with time were measured. It is shown that the material presents good mechanical strength and excellent physical and thermal properties. The behaviour of the material on fire was tested by subjecting it to thermal loading with the modification of a standardized passive fire protection test. Two different fire scenarios were investigated: (1) the least intensive standard ISO 834 fire load curve and (2) the most severe Rijkswaterstaat fire load curve. The material behaviour was excellent under its exposure at the ISO 834 fire load curve, showing optimal thermal insulating function and very good structural integrity. Under the Rijkswaterstaat fire load curve, the material showed again a very good thermal insulating function while at the same time suffered from creeping phenomena at the extremely high temperature of 1300°C that affected drastically its structural integrity. As a conclusion, the sodium‐based geopolymer from FeNi slag may be an appropriate material for passive fire protection systems under cellulosic fires but inappropriate against more intense fire incidents. Copyright © 2014 John Wiley & Sons, Ltd.     

浅述几类化学危险品的基本特性、火灾预防措施及灭火方法

化学危险品是具有爆炸、易燃、毒害、感染、腐蚀、放射性等危险特性,在运输、储存、生产、经营、使用和处置中,容易造成人身伤亡、财产损毁或环境污染而需要特别防护的物品。文章介绍了易燃固体、自燃物品及遇水放出易燃气体的物质、易燃液体、危险气体、爆炸品、毒性物质和感染性物质、氧化性物质和有机过氧化物六类化学危险品的基本特性,说明了其火灾预防措施,并概述了它们在发生灾害事故时的处置措施或灭火方法。     

Evaluating the communication within fire and rescue services and the NHS on the fire risk of emollients in accordance of the MHRA safety update

The Medicines and Healthcare products Regulatory Agency update in 2018 reported 50 fatal fires linked with emollient use. It detailed the fire risk and new advice aimed at fire service and health care professionals in reporting of such fire incidents and educating the public on safer use of emollients. This study investigates how this has been communicated internally and publicly, with 52 Fire and Rescue Services (FRSs) websites and, 191 Clinical Commissioning Groups (CCGs), and 21 Local Health Boards (LHBs) formularies accessed. A Freedom of Information Request (FOIR) was also made, giving further details of implementations. Our study revealed that 63% of FRSs, 32% of CCGs and, 72% of LHBs gave no safety advice within their website or formularies. Of the 37% of FRSs and 68% of CCGs that did, only 5% and 4% were sufficiently up to date. 27% of FRSs and 28% of CCGs/LHBs revealed that they had no warning/advice internally in their FOIR responses and 25% of FRSs and, 35% of CCG/LHBs had not disseminated advice on using emollient safely to the public. We suggest improvements in safety campaigns using a multiagency and national approach and recommend organizations to educate professionals to improve reporting and effective dissemination.     

The effects of transient heat release rate and crosswind on flame length and tilt angle of flames at different positions in the spread of fire over a diesel pool

The spread of fire over liquid fuel is a common phenomenon, and it has been demonstrated experimentally that the flame length and tilt angle change with the transient heat release rate and different positions of the flame. The coupling relationship between these factors is studied in this paper. The experiments are composed of a rectangular pool with dimensions of 80 cm × 6 cm × 5 cm and crosswind with speeds of 0.8 to 2.4 m/s. Diesel is used as the fuel, and a new method is applied to ensure that the initial temperature of the diesel is constant during ignition. The results show that the traditional method of luminous flame intermittency may not be suitable for studying the geometric characteristics of the spread of fire over a pool, and a new method is proposed. In addition, the transient variation of flame length in different positions of the pool is shown to fluctuate around a mean flame length. The evolution of flame tilt angle along the longitudinal direction of the pool exhibits a U‐shaped curve. Moreover, the multivariate nonlinear relationships of mean flame length and tilt angle among the heat release rate, fire position, and wind speed are established, and relevant coefficients are determined.