MEASUREMENT OF FIREBRAND PRODUCTION AND HEAT RELEASE RATE (HRR) FROM BURNING KOREAN PINE TREES Samuel L. Manzello, Alexander Maranghides, John R. Shields, and William E. Mell Building and Fire Research Laboratory (BFRL) National Institute of Standards and Technology (NIST) Gaithersburg, MD 20899-8662 USA Corresponding author: samuel.manzello@nist.gov , +1-301-975-6891 (office), +1-301-975-4052 (fax) Yoshihiko Hayashi and Daisaku Nii Department of Fire Engineering Building Research Institute (BRI) Tsukuba, Ibaraki 305-0802 Japan ABSTRACT A series of real scale fire experiments were performed to determine the mass and size distribution of firebrands generated from Korean Pine (pinus koraiensis) trees. The experiments were performed at the Building Research Institute (BRI) in Tsukuba, Japan. The tree height was fixed and tree moisture content was varied to examine the influence that this parameter has on the mass and size distribution of the firebrands that are produced, under ambient wind conditions. The firebrands were collected using an array of water filled pans. This ensured that firebrands would be quenched as soon as they made contact with the pans. The Korean Pine trees were also mounted on load cells during burning to determine the temporally resolved mass loss profiles. The mass loss data were used to calculate the mass loss rate and infer peak heat release rate (HRR). Results of this study are presented and compared to firebrand distribution and HRR of burning Douglas-Fir trees, a conifer tree species indigenous to the USA. KEYWORDS: Firebrands, Wildland/Urban Interface Fires, Heat Release Rate (HRR) INTRODUCTION A major complication for fire spread in communities is the generation of firebrands 1-2 . Firebrands are generated as structures and vegetation burn in wildland urban interface (WUI) fires. Firebrands that are produced are entrained in the atmosphere and may be carried by winds over long distances (up to several kilometers in some cases). Ultimately, hot firebrands with significantly long burn-out time land on fuel sources far removed from the initial fire, resulting in fire spread. This process is commonly referred to as spotting. Firebrand ignition has been an outstanding problem that has plagued both the USA and Japan. Unfortunately, a very limited number of experimental studies have been performed to investigate the mass and size distribution of firebrands produced from burning vegetation and structures 1-2 . The firebrand problem can de divided into three main processes: the generation of firebrands from burning vegetation and structures, their subsequent transport through the atmosphere, and the ultimate ignitability of materials due to their impact 3 . Of these, firebrand transport has been studied most extensively 4-12 . Models have been developed to perform firebrand transport calculations; such models have assumed firebrand sizes to perform these calculations since little quantitative data exists with regard to firebrand size or firebrand mass produced from vegetation and structures. Experimentally determined regime maps that relate firebrand size and firebrand mass distribution generated from common vegetation species are required. Naturally, such regime maps are also a function of vegetation moisture content, vegetation geometry (i.e. size and shape), the particular