Characteristics of Firebrands Collected from Actual Urban Fires

Abstract

The characteristics of firebrands collected from a recent urban fire in Japan are described. Specifically, this fire broke out from a Chinese restaurant in Itoigawa-city, Niigata, Japan on December 22nd 2016. On the day of the fire, strong winds resulted in rapid fire spread. With the presence of an average wind speed of 9 m/s, the fire quickly spread, resulting in the damage of 147 structures, with 120 of 147 destroyed. The fire was extinguished more than 30 hours later. During the fire, firebrands were observed and 10 spot fires were reported. After the fire, investigations were performed and firebrands were collected from the burn site. The size and the mass of firebrands were measured and compared with the available literature data. It was observed that more than 60 % of the collected firebrands had less than 0.10 g mass and 2.0 cm2 projected area and the size and the mass of firebrands were independent of the location. The size and the mass of firebrands from this fire were similar to those from another urban fire under similar wind speed and were also compared to those produced from a firebrand generator. The firebrand data set presented here provided valuable insights into how firebrands are generated from structures in actual urban fires. Finally, the description on how a firebrand generator may be used to produce firebrands similar to urban fires yields an important advancement to begin to study such complex phenomena in the laboratory.

Quantifying wind‐driven firebrand production from roofing assembly combustion

“…The easiest method to visualize this is to imagine a sheet paper, as firebrands are often of very thin thickness, so the largest projected area is of interest. Images of specific shapes that have known areas (eg, circles) were used to determine the ability of the image analysis method to calculate the projected area . The standard uncertainty in determining the projected area was ±10%.…”

“…A unique aspect of this paper is that such a comparison is provided. Because of deployment of rapid investigative teams by the National Research Institute of Fire and Disaster (NRIFD), firebrands were hand collected from rooftops of buildings and other areas that were protected from firefighting suppression efforts. It is important for the reader to grasp that water pans were not placed during an actual fire but the collected firebrands were wetted from the suppression efforts.…”

“…Firebrands are an important structure ignition mechanism in both WUI and urban fires. Hardly any data exist for firebrand size distributions from actual structures or large outdoor fires, such as WUI and urban fires . In WUI fires, the structures themselves are a large source of firebrands, in addition to the vegetation .…”

Reducing Wooden Structure and Wildland-Urban Interface Fire Disaster Risk through Dynamic Risk Assessment and Management

“…Research in Japan and the USA has also focused on fire spread between wooden structures, e.g., [27,28]. Due to increased international challenges regarding large outdoor fires and the built environment, the International Association of Fire Safety Sciences (IAFSS) established an international work group on this issue after discussions at the IAFSS 2017 conference in Lund, Sweden [29].…”

Investigating Coupled Effect of Radiative Heat Flux and Firebrand Showers on Ignition of Fuel Beds

“…1. Firebrands are pro-duced and lead to enhanced fire spread processes [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Often referred to as spotting processes, firebrands are liberated from the combustion of various fuel types, such as trees, shrubs, houses, and then induce ignition of fuel sources away from the initial fire source.…”