Wind Driven Structure Fires
I recently attended the first annual Brunacini Hazard Zone Management Conference at the University of Notre Dame in Indiana. Chief Alan Brunacini delivered the opening remarks and seminar overview. He was in fine form, demonstrating his passion for and commitment to the fire service and the public they serve. His comments were followed by a series of workshops facilitated by first class knowledgeable speakers. The setting was beautiful and the facilities were perfect.
Over the next few weeks I will be sharing some of the highlights of the conference with you starting with:
Wind Driven Fires
Wind can increase the spread of fire gases through a building. Heat and smoke in the corridors and stairways can prevent fire fighters from suppressing the fire from inside the structure. Wind driven fires have caused fire fighter injuries and fatalities.
For example, on April 16, 2007, a 24-year-old career fire fighter was fatally injured while trapped in the master bedroom during a wind-driven residential structure fire. The victim and his lieutenant, wearing their SCBA, entered the residence through the unlocked front door. With light smoke showing, they walked up the stairs to check the bedrooms. With smoke beginning to show at ceiling level, the fire fighter conducted a search while the lieutenant, with thermal imaging camera (TIC) in hand, checked the bed. Suddenly the room turned black, then orange with flames. The lieutenant yelled to the fire fighter to get out. The lieutenant found the doorway and moved toward the stairs. He ended up falling down the stairs to a curve located midway in the staircase. As the wind gusted up to 48 miles per hour, the wind-driven fire and smoke engulfed the residence. The lieutenant received burns on his ears and right index finger. The fire fighter's body was found in the master bedroom.
On April 12, 2009, a 30-year old career probationary fire fighter and a 50-year old career captain were killed when they were trapped by rapid fire progression in a wind-driven residential structure fire. The victims were members of the first arriving company and initiated fast attack offensive interior operations through the front entrance. Less than six minutes after arriving on-scene, the victims became disoriented as high winds pushed the rapidly growing fire through the den and living room areas where interior crews were operating. Seven other fire fighters were driven from the structure but the two victims were unable to escape.
Key contributing factors identified by NIOSH in their investigation included:
- lack of understanding of fire behavior and fire dynamics;
- fire in a void space burning in a ventilation controlled regime;
- high winds;
- uncoordinated tactical operations, in particular fire control and tactical ventilation;
- and failure to react appropriately to deteriorating conditions.
Although there is no evidence that the following recommendation could have specifically prevented the fatalities, NIOSH investigators recommend that fire departments:
- ensure that all fire fighters recognize the capabilities and limitations of their personal protective equipment when operating in high temperature environments.
The NIOSH investigators' recommendations also included:
- ensure that fire fighters and officers have a sound understanding of fire behavior and the ability to recognize indicators of fire development and the potential for extreme fire behavior (such as smoke color, velocity, density, visible fire, heat);
- ensure that fire fighters are trained to recognize the potential impact of windy conditions on fire behavior and implement appropriate tactics to mitigate the potential hazards of wind-driven fire;
- ensure that fire fighters understand the influence of ventilation on fire behavior and effectively apply ventilation and fire control tactics in a coordinated manner;
- ensure that fire fighters and officers understand the capabilities and limitations of thermal imaging cameras (TIC) and that a TIC is used as part of the size-up process;
- ensure that fire fighters are trained to check for fire in overhead voids upon entry and as charged hoselines are advanced;
- and conduct research to more fully characterize the thermal performance of self-contained breathing apparatus (SCBA) face piece lens materials and other personal protective equipment (PPE) components to ensure SCBA and PPE provide an appropriate level of protection.
Evaluating Fire Fighting Tactics Under Wind Driven Conditions
Daniel Madrykowski, an Engineer with the National Institute of Standards and Technology (NIST), delivered a presentation on recent NIST tests, including "Evaluating Fire Fighting Tactics Under Wind Driven Conditions". He provided copies of a DVD showing tests conducted in conjunction with Chicago and New York Fire Departments. The video will be available soon at http://www.nist.gov/fire/wdf.cfm
Wind blowing into the broken window of a room on fire can turn a "routine room and contents fire" into a floor-to-ceiling firestorm. Historically, this has led to a significant number of firefighter fatalities and injuries, particularly in high-rise buildings where the fire must be fought from the interior of the structure.
The test fires in the video show the dramatic growth of fire when the window in the room of fire origin fails, allowing large amounts of air to enter. The video also shows the fire department deploying a low-tech wind control device (WCD) which limits the entrainment of air to the fire. The WCD (or blanket by any other name) can be seen in this picture.
This is a very simple but effective tool. Perhaps the fire service needs to rethink ventilation practices, especially in wind driven events.
In NIST's experiments, the WCDs reduced the temperatures in the corridor and the stairwell by more than 50% within 120 seconds of deployment. The WCDs were exposed to a variety of extended thermal conditions without failure.
For more information please click on this link.
