bureau of alcohol, tobacco, firearms and explosives

bureau of alcohol, tobacco, firearms and explosives

ATF MAYDAY/LODD Fire Modeling Analysis with Scene Audio, FF Mark Falkenhan, Baltimore County FD

2d ago
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INTRODUCTION: This video summarizes the ATF Fire Research Laboratory's Engineering Analysis of the fire that occurred at 30 Dowling Circle on January 19th, 2011 using actual scene audio, photographs and computer fire modeling video. ATF Fire Protection Engineers were asked to utilize engineering analysis methods, including computer fire modeling, to assist with determining the route of fire spread and the events that led to the firefighter MAYDAY and subsequent Line of Duty Death of Firefighter Mark Falkenhan. The complete analysis can be found in the printed engineering analysis report auhtored by Fire Protection Engineer Adam St. John, PE at the link below: http://www.baltimorecountymd.gov/bin/a/m/b_atffireanalysis120319.pdf BACKGROUND: Working closely with the Post Incident Analysis Team, the ATF Fire Research Laboratory created a computer representation of the garden apartment building using Fire Dynamics Simulator (FDS). FDS is a computational fluid dynamics (CFD) modeling program developed by the National Institute of Standards and Technology (NIST). FDS utilizes mathematical calculations to predict the flow of heat, smoke and other byproducts of fire. Smokeview, a post-processer computer program also produced by NIST, was then used to visualize the mathematical output from FDS. The most current available versions of both programs were used, FDS 5.5.3 and Smokeview 5.6. The garden apartment building at 30 Dowling Circle was attached to two similar garden apartment buildings, one on each side. The fire damage was isolated to 30 Dowling Circle, so the exposure buildings were not included in the computer fire model. The entire six unit garden apartment building was modeled in FDS, including the patio and balconies on the rear of the building. FDS works by dividing a space into cubical "grid cells" for calculation purposes. FDS then computes various CFD calculations for each grid cell to predict the movement of mass, energy, momentum and other species throughout a three-dimensional space. The Dowling Circle model consisted of 2,560,000 total grid cells that were each 3.9 inches (10 cm) cubes. The model spanned a total elapsed time of 27.5 minutes, beginning before the 911 call and ending just after flashover of the third floor and the firefighter MAYDAY. The model was synchronized real time with the scene audio throughout the duration of the fire. CONCLUSION: While no fire model will exactly replicate a fire, this model provided insight on the route of fire spread, the rapid flashover of the second and third level, and the potential benefits of compartmentation on slowing fire and smoke spread. The unidirectional flow path up the stairs from the terrace level apartment resulted in a high rate of convective heat transfer to the firefighters initially attempting to descend the stairs, making attacking the seat of the fire very difficult. The model then the fact that the main stairwell acted as an open channel for fire and smoke spread between the second and third levels, resulting in flashover of the third level in approximately 30 seconds after the second level. This rapid time to flashover is supported by photographs, witness statements and scene audio. The model was then utilized to explore the effects of compartmentation using apartment entrance doors. The FDS model supported the scene observations and indicated that shutting the entrance doors blocked the buoyancy driven ventilation flow paths through the structure and slowed the spread of fire and smoke, ultimately preventing fire extension to the third floor apartment via the stairwell. The FDS model was utilized as part of the overall engineering analysis of this tragic fire and was utilized to gain a better understanding of the events that led to the firefighter MAYDAY and subsequent Line of Duty Death. The model was also used as an educational tool, providing insight on potential methods of preventing similar tragedies in the future. ...