An experimental study on backdraught: The dependence on temperature

Wu, Chia Lung; Carvel, Ricky

doi:10.1016/j.firesaf.2017.04.003

Cited by 9 publications

(5 citation statements)

References 14 publications

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“…It is observed that when CO/CO 2 was above 0.35, backdraft occurs, lower than this value, the spark can only ignite the unburned smoke and re-ignite the fuel tray only, with no obvious fireball indicating backdraft. It should be noted that even with an extremely long time of door closure with lower temperature about 200°C, a re-ignition is still possible, for details see [20]. It should also be noted that there were only three instances of backdraft observed in this series of eight piloted ignition tests, so it is hard to define the boundary between backdraft and non-backdraft events with any confidence.…”

Section: Gas Concentrationsmentioning

confidence: 91%

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Critical Factors Determining the Onset of Backdraft Using Solid Fuels

Santamaria

Carvel

2019

Fire Technol

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Backdraft is an explosive fire phenomenon which typically occurs during fire-fighting activities, occasionally leading to fire-fighter fatalities. Real backdraft incidents involve complex fuel gas mixtures consisting of the products of underventilated burning and pyrolysis following burnout. However, most experimental research into backdraft has used methane gas or flammable liquids as fuel. Some aspects of real backdraft behavior may have been overlooked as a consequence of this simplicity. A reduced scale series of compartment fire tests have been carried out to investigate the critical factors governing the onset of backdraft, using polypropylene and high density polyethylene samples as fuel. It is established that there are critical temperatures for auto-ignition of the pyrolysis gases leading to backdraft which vary with fuel properties. For polypropylene the highest temperature in the compartment must be above 350°C for auto-ignition of the fuel gases, while mixtures in the presence of a pilot source can be ignited down to about 320°C. Backdraft cannot occur when the compartment temperature is below 320°C. For polyethylene, the corresponding temperature for auto-ignition is 320°C. In parallel with these tests, a series of pyrolysis investigations have been carried out using the fire propagation apparatus, with FTIR gas analysis. The observed critical temperatures for backdraft correlate well with the evolved pyrolysis gases. Analysis shows that higher temperatures are required for backdraft when the CO/CO 2 ratio is small, and that below the auto-ignition temperature, backdraft can only occur above a CO/CO 2 ratio of about 35%. It is concluded that the crucial factors determining whether backdraft occurs or not are the maximum temperature and the CO/CO 2 ratio in the compartment, prior to opening the door.

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Section: Gas Concentrationsmentioning

confidence: 91%

“…The conditions for backdraft can be achieved after a fire has become well established, but it has already been demonstrated that fire growth to flashover is not required [20]. Flashover, when it occurred, was identified during these tests by a rapid increase in burning rate, a significant increase in temperature, and external plume burning.…”

Section: Methodsmentioning

confidence: 99%

Critical Factors Determining the Onset of Backdraft Using Solid Fuels

Santamaria

Carvel

2019

Fire Technol

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“…Наиме, током пожара у затвореном простору мо же се постићи фаза у којој топлотно зрачење пламена, врући га совити продукти сагоревања и загрејане површине кон стру к тив них елемената грађевинске конструкције објекта проузрокују пи ролизу свих присутних горивих материјала и њихово паљење. Овај изненадни и нагли прелаз пожара из фазе развоја у потпуно развијену фазу назива се флешовер (flashover) (Wu, Carvel, 2017). За разлику од флешовера, који подразумева пламени удар венти ли саног простора, у одређеним условима ограничена вентилација може резултирати још значајнијом концентрацијом смеше проду ка та непотпуног сагоревања и несагорелих продуката пиролизе.…”

Section: уводunclassified

Safety of firefighters-rescuers during training in flashover container: A numerical study

Pešić¹,

Zigar²,

Blagojević³

2022

Bezbednost, Beograd

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Extinguishing of fire is a responsible and risky job that requires knowledge, skill and mental stability from the firefighter. These facts especially refer to the localization and extinguishing of enclosure fires where the occurrence of flaming attacks, such as flashover and backdraft are possible. In such conditions, lack of experience of firefighters often leads to fatal injuries. In order to reduce the injuries of firefighters during firefighting interventions, their training in flashover containers has recently begun. Practical training provides the necessary experience that is applied in real fire extinguishing interventions which implies that firefighters are exposed to high fire temperatures during training. Because of this, the paper focuses on modeling and simulation of flashover appearance in a container for firefighters' training, performed by using numerical fluid dynamics method. Using the Fire Dynamics Simulator software package, seven fire scenarios under different ventilation conditions and fire extinguishing methods were analyzed, with the aim of examining container temperatures that affect the safety of firefighters during the training. The obtained results indicate that the most acceptable scenario for firefighter training means that the container door is open for the entire duration of the training and, at the same time, it neccessary to periodically extinguish fire with a water jet, along with occasionally opening of the roof vent of the container.

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“…According to the experimental results, they established a theoretical model and deduced the critical condition of backdraft. Wu et al [ 26 , 27 ] conducted reduced-scale experiments to study temperature conditions and critical factors of backdraft. Their results indicated that before the opening of a compartment, maximum temperature and the CO/CO2 ratio in the compartment were crucial factors that determined whether backdraft occurred or not.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the backdraft phenomenon of solid fuel

Zhao

et al. 2021

PLoS ONE

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In this study, a series of small-scale experiments were conducted to investigate the backdraft phenomenon in a compartment (1.1 × 0.4 × 0.75 m) with woodblocks as fuel. This research focused on the effects of compartment window woodblock areas on backdraft time, with a video recording of the experimental phenomena. Thermocouples and a gas analyzer were used to measure the temperature and the concentration of gas components in the compartment, respectively. There was no additional heat source or ignition source pre-set in the compartment at the beginning of the experiments; the experimental processes only depended on the heat released from the burning or smoldering of woodblocks. When compartment ventilation improved, smoldering of woodblocks became intense, and backdraft occurred. The results show that backdraft time is shorten with increases of compartment window and woodblock areas, and opening the upper window of a compartment could avoid the backdraft phenomenon. The results help to understand the backdraft phenomenon of solid fuel and, more importantly, could help firefighters adopt reasonable fire-fighting strategies for restraining backdraft occurrence.

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An experimental study on backdraught: The dependence on temperature

Cited by 9 publications

References 14 publications

Critical Factors Determining the Onset of Backdraft Using Solid Fuels

Critical Factors Determining the Onset of Backdraft Using Solid Fuels

Safety of firefighters-rescuers during training in flashover container: A numerical study

Experimental study on the backdraft phenomenon of solid fuel

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