Effects of Leakage in Simulations of Positive Pressure Ventilation

2015

Fire Dynamics Simulator (FDS), which is a fire model that is developed and maintained by the Na tional Institute of Standards and Technology (NIST), was used to provide insight into the dynamics of a fire that occurred on February 24, 2012, within a single-story, single-family residential struc ture in Riverdale Heights, MD, that resulted in the serious injury of two Price George's County firefighters. The inputs for the FDS simulation are documented in this report and are based on the fire scenario, including the building geometry, interior furnishings, and ventilation conditions. The fire started in the basement which generated ventilation limited (fuel rich) fire conditions in the basement area. After the front door was opened, the interior stairwell, aided by strong winds blow ing into the basement, acted as a chimney for hot gases in the basement to flow towards regions of lower pressure, out through the front door. The temperature of the gases in the interior stairwell was estimated to be in excess of 400 • C (750 • F). Two firefighters were located in the flow path be tween the interior stairwell door and the front door of the structure, were exposed to these elevated temperatures, and suffered serious burn injures. Five additional firefighters were injured during fire operations on the first floor.

Section: Ventilationmentioning

confidence: 99%

Simulation of a Residential Wind Driven Basement Fire - Riverdale Heights, MD

Weinschenk¹,

Overholt²,

2015

“…The times of the ventilation changes are provided in Table 3.1. Structure leak age has been shown to be important when modeling enclosure fires [19]. The open front door at the start of the simulation and the vents (opening size and open time) created during the simulation are significantly larger than the total effective area of leakage of a structure of this type.…”

Section: Ventilationmentioning

confidence: 99%

Simulation of an Attic Fire in a Wood Frame Residential Structure - Chicago, IL

Weinschenk¹,

Overholt²,

2014

The Fire Dynamics Simulator (FDS) fire model, which is developed and maintained by the National Institute of Standards and Technology (NIST), was used to provide insight into the dynamics of a fire that occurred on November 2, 2012, within a 2 1 ⁄2 story, single family structure in Chicago, IL, that resulted in the death of the captain of a fire department. The inputs for the FDS simulations are documented in this report and are based on the fire scenario, including the building geome try, interior furnishings, and ventilation conditions. The fire started in the attic and spread down through an opening into the enclosed porch on the rear of the structure. This resulted in ventilation limited (fuel rich) fire conditions in the attic and rear porch areas. The spread of fire and hot gases into the second floor of the structure was limited by a closed steel-faced, wood-framed door. After exposure to the elevated temperatures and pressure from the fire in the porch area, the wood frame of the door decomposed, the steel faces of the door failed, and the door collapsed inward. The door failure resulted in the establishment of a flow path between the higher pressure and higher temper ature conditions in the enclosed porch and the lower pressure and lower temperature conditions in the hallway and kitchen areas of the second floor. The temperature of the gases that flowed into the hallway exceeded 260 • C (500 • F) at a height of 1.86 m (6 ft). Unfortunately, a captain and firefighter were advancing a hose line in the hallway near the door at the time of the door failure. It appears that the captain was likely overcome by the rapid change in conditions before he could exit to the safety of the kitchen area. After a Mayday call, the captain was rescued from the structure, but later succumbed to his injuries.

“…Air leakage in structures has been shown to be an important consideration when modeling enclosure fires [21]. The open front door at the start of the simulation and the vents created during the simulation are significantly larger than the total effective area of leakage of a structure of this type.…”

Section: Ventilationmentioning

confidence: 99%

Simulation of a Fire in a Hillside Residential Structure - San Francisco, CA

Overholt¹,

Weinschenk²,

2014

Fire Dynamics Simulator (FDS), which is a fire model that is developed and maintained by the Na tional Institute of Standards and Technology (NIST), was used to provide insight into the dynamics of a fire that occurred on June 2, 2011, within a multi-level, single-family residential structure in San Francisco, CA, that resulted in the death of two firefighters. The inputs for the FDS simulation are documented in this report and are based on the fire scenario, including the building geometry, interior furnishings, and ventilation conditions. The fire started in the basement and resulted in ventilation limited (fuel rich) fire conditions in the basement area. After the rear basement win dows began to fail, the interior stairwell acted as a chimney for hot gases in the basement to flow towards regions of lower pressure and vent openings located on the front side of the structure. The temperature of the gases in the interior stairwell was estimated to be in excess of 700 • C (1300 • F). Two firefighters were located in the flow path between the basement and the doors on the front side of the structure, were exposed to these elevated temperatures, and later died as a result of their injuries.