Establishing safety distances for wildland fires

Zárate, Luis Gonzaga Alonso; Arnaldos, Josep; Casal, Joaquim

doi:10.1016/j.firesaf.2008.01.001

Cited by 93 publications

(79 citation statements)

References 9 publications

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“…These values are generally higher than the values predicted for safety zones using the physically based models. However, at flame heights exceeding 10 m, for all combinations of fire shelter use and probability level, the required SDFH ratios decrease and eventually become lower than Butler and Cohen's (1998a) model but similar to the models proposed by Zárate et al (2008) and Rossi et al (2011), generally ranging from 1 to 4 times the flame height.…”

Section: Fatal Injury Model (Survival Zone Separation Distance)supporting

confidence: 62%

“…Several factors could be causing this difference, which include addressing a known underprediction bias in the physical models, determination of the actual probability level that is acceptable for non-fatal injuries and model quality. Underprediction of separation distance in the current set of physically based models is likely related to the failure to include the effects of convective heat transfer on safety zone size (Zárate et al 2008;Butler 2014aButler , 2014b) and the use of burns to bare skin as the only mechanism of injury. A safety zone should be an area of sufficient size to ensure that firefighters remain uninjured from all possible injury mechanisms including excessive inhalation of smoke or hot combustion gases (National Wildfire Coordinating Group 1996).…”

Section: Discussionmentioning

confidence: 99%

“…Particular emphasis was placed on gathering information related to the key variables identified in previous research (Butler and Cohen 1998a;Zárate et al 2008;Rossi et al 2011;Butler 2014a), such as flame height (or flame length) and separation distance from the flames. An attempt was made to estimate the variables of interest when they were not explicitly described using photographs or other descriptive information.…”

Section: Data Collectionmentioning

confidence: 99%

“…Without a fire shelter or vehicle, the required separation , and 1% (bottom row, c and d) probability thresholds. Estimates of the separation distance flame height ratios from three physically based safety zone models are shown for comparison: Butler and Cohen (1998a), solid line; Rossi et al (2011), dashed;Zárate et al (2008), long dash. distances at the 1% probability level were 275, 209 and 232 m for the brush, grass and timber fuel types respectively.…”

Section: Non-fatal Injury Model (Safety Zone Separation Distance)mentioning

confidence: 99%

“…A more recent model advanced by Butler and Cohen (1998a) was also developed based on radiant heating, which was distilled to a general guideline suggesting that the separation distance between the firefighters and the flames should be at least 4 times the flame height (Butler and Cohen 1998b;National Wildfire Coordinating Group 2014). Additionally, Zárate et al (2008) and Rossi et al (2011) produced other physically based radiant heat transfer models of safe separation distance using similar approaches with different assumptions regarding flame front temperature and width. Despite the wide use of these models in operational settings, they have known limitations in regards to their assumptions of using only radiant heating, no wind or slope influence, failing to incorporate mechanisms of injury other than burns to bare skin, and the lack of direct validation in the field (Butler 2014a).…”

Section: Introductionmentioning

confidence: 99%

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An empirically based approach to defining wildland firefighter safety and survival zone separation distances

Page

Butler

2017

Int. J. Wildland Fire

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Abstract. Wildland firefighters in the US are mandated to identify areas that provide adequate separation between themselves and the flames (i.e. safety zones) to reduce the risk of burn injury. This study presents empirical models that estimate the distance from flames that would result in a low probability (1 or 5%) of either fatal or non-fatal injuries. The significant variables for the fatal injury model were fire shelter use, slope steepness and flame height. The separation distances needed to ensure no more than a 1 or 5% probability of fatal injury, without the use of a fire shelter, for slopes less than 25% were 20 to 50 m for flame heights less than 10 m, and 1 to 4 times the flame height for flames taller than 10 m. The non-fatal injury model significant variables were fire shelter use, vehicle use and fuel type. At the 1 and 5% probability thresholds for a non-fatal injury, without the use of a fire shelter, the separation distances were 1 to 2, 6 to 7, and 12 to 16 times greater than the current safety zone guideline (i.e. 4 times the flame height) for timber, brush and grass fuel types respectively.Additional keywords: fire behaviour, firefighter entrapment, flame height, safe separation distance.

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Section: Fatal Injury Model (Survival Zone Separation Distance)supporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Data Collectionmentioning

confidence: 99%

Section: Non-fatal Injury Model (Safety Zone Separation Distance)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An empirically based approach to defining wildland firefighter safety and survival zone separation distances

Page

Butler

2017

Int. J. Wildland Fire

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Numerical prediction of fire dynamics and the safety zone in large‐scale multiple pool fire in a dike using flamelet model

Nemalipuri,

Singh,

Vitankar

et al. 2023

Can J Chem Eng

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This research aims to develop a computational fluid dynamics (CFD) methodology for estimating the safety zone around a dike with multiple pool fire (MPF). This study predicts the safety zone and burning characteristics of heptane MPF inside a square dike in calm wind and worst‐case crosswind situations using unsteady simulations. The heptane MPF is modelled using flamelet approach with large eddy simulation (LES) turbulence model incorporating the soot generation. Discrete ordinates and Moss–Brookes model estimate the effect of participating medium radiation on prediction of safety distance and soot production. The discretization is incorporated using an isotropic trimmed cell mesher with local refinement to resolve the flame characteristics in Simcenter STAR CCM+. An extensive grid‐independence study has been executed to find the optimal mesh. The flame temperature and O2 and CO2 mass fraction predictions in calm wind conditions are in good agreement with the experimental findings of Koseki and Yumoto and the maximum flame temperature predictions are within 2.8% error. The safety zone is predicted using the estimated radiative heat flux. The effect of different ordinate sets (angular discretization S4, S6, and S12) approach on safety distance prediction is investigated. The validated grid independent CFD model combined with flamelet generated manifold model and LES turbulence model is proposed to predict the safety zone for industrial MPF in crosswind scenarios, thereby preventing human fatalities and property loss.

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Distribution characteristics of radiant heat flux on tank surfaces exposed to wildland fires

Wang,

Zhou

2024

Fire and Materials

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The expansion of wildland‐urban interface tends to expose fuel tanks to wildland fires, the frequency and intensity of which have increased in recent years due to climate change and global warming. This study aims to examine the distribution of radiant heat flux on a tank surface exposed to a wildland fire front, with a particular focus on extreme wildland fires. A theoretical framework is proposed, which consists of a flame length correlation, a thermal radiation model, and a correlation of time to failure, to calculate the radiant heat flux received by the tank surface and the potential for tank failure. The horizontal and circumferential distribution characteristics of the radiant heat flux are intensively discussed, in terms of the heat flux profile, heating area, total heat, time to failure versus the fireline intensity, fireline width, spacing, and tank volume. In particular, extreme wildland fires, characterized by large fireline intensities, could potentially destroy the tank within the safety spacing mandated by the current regulations. Therefore, a comparison between the time to failure and the radiant heating duration is suggested to ascertain the necessary safety spacing. The uncertainties in model calculations are also addressed, which arise from the use of different flame length correlations and flame radiative fractions.

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Establishing safety distances for wildland fires

Cited by 93 publications

References 9 publications

An empirically based approach to defining wildland firefighter safety and survival zone separation distances

An empirically based approach to defining wildland firefighter safety and survival zone separation distances

Numerical prediction of fire dynamics and the safety zone in large‐scale multiple pool fire in a dike using flamelet model

Distribution characteristics of radiant heat flux on tank surfaces exposed to wildland fires

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