By Peter Hunt
By Peter Hunt
Ottawa Fire Capt. Peter Hunt summarizes the FDNY’s symposium on wind-driven fires in his Fire IQ column in the October issue of Canadian Firefighter and EMS Quarterly.
Every so often, information emerges that seems so important and potentially life saving that you feel a need to share it with everyone. Such was the case when I attended a high-rise firefighting symposium presented by the Fire Department of New York and learned of new research about wind-driven fires in high-rises.
There are two points I want to make immediately clear.
- Although we will focus on the effect of wind on fires in high-rise buildings, any size or type of building can be affected and all firefighters must be aware, regardless of the size of their department.
- A thorough explanation of wind-driven fires is beyond the scope of this article. Readers are encouraged to check the website listed below.
Everyone has seen dramatic footage of massive forest fires driven by the wind with blowtorch-like effects. New research, conducted over the past couple of years, suggests that wind can have an equally devastating effect on structure fires in urban settings. When certain conditions exist, a routine structure fire can become a potentially deadly event for firefighters who fail to recognize the signs of a wind-driven fire and adjust their strategies and tactics accordingly.
Typically, five conditions need to be present for a wind-driven structure fire to exist: the fire itself (in a high-rise apartment for the purpose of our discussion); an open door from the fire apartment (either left open by fleeing occupants, or opened by us); a failed or open window; wind; and a ventilation outlet or path for fire travel.
The majority of high-rise fires are not wind-driven events, and thankfully most of us will never experience one. Nevertheless, failure to recognize the warning signs could result in the serious injury or death. Be aware that wind conditions at ground level may not be indicative of conditions on upper floors. Some signs may be evident from the exterior on arrival such as flames or smoke in an open apartment window that is not venting out as expected. In some cases, flame or smoke will vent from the window but in an unusual way as flame or smoke occasionally overcomes the wind and creates pulsating patterns or pushes from the corners or sides of the window.
Some signs may be evident upon entering, or once inside the building. Doors leading into the building may be difficult to open, or a persistent outflow of air suggests a high pressure condition created by the wind. There may be unusually strong wind conditions in the elevator shaft or stairwells. Conditions on the fire floor may be so severe as to prevent firefighters from entering the hallway. If you can make the floor, the door leading to the fire apartment may be warped, discoloured by heat, leaking smoke under pressure or otherwise showing signs of imminent failure.
Opening the fire apartment door after failing to recognize these signs could be the triggering event that causes a blow torch of fire to exit the apartment, enter the common hallway and head in the direction of any available ventilation opening without regard for the presence of firefighters or civilians. Members in the hallway will immedi-ately be overcome by potentially deadly heat and fire and traditional hose streams may be ineffective in cooling or extinguishment.
In the event that firefighters have time to seek refuge, they should retreat to the stairwell and close the door or enter an apartment on the same (windward) side as the fire apartment, and notify command of conditions.
Whether wind-driven conditions are determined on arrival or upon making the fire floor, alternate firefighting strategies must be employed by command.
- Interior members must stand fast in safe areas.
- All ventilation inlets and outlets must be strictly controlled as the fire desperately tries to move to areas of lower pressure.
- Water must be applied by non-traditional methods to cool the fire apartment to the point where a traditional frontal attack may take place.
The following alternative methods of water application may be considered depending on the location of the fire and whether firefighters can operate on the fire floor or floors above and below:
- If the adjacent apartment is accessible, firefighters can breach the common wall near the exterior wall and introduce water into the fire apartment using a hand line. They may also be able to “reach around” from the adjoining balcony or window.
- Water may be introduced into the fire apartment through the exterior window by a large-diameter hand line from the ground or an aerial device.
The FDNY is experimenting successfully with the deployment of wind-control devices (fire blankets) from the floor above and specialized floor-below fog nozzles. Research conducted by the Ottawa Fire Department intended to complement the work of the FDNY strongly supports the deployment of a Bresnan (rotary) nozzle from a floor or two above as an alternative strategy. When suspended directly outside the fire apartment window and charged from the buildings standpipe system, this extremely stable appliance will take advantage of the prevailing wind and introduce large volumes of water into the apartment with a dramatic cooling effect.
Once the extreme conditions of a wind-driven fire are diminished, traditional methods of extinguishment and overhaul may be resumed. For more information visit fire.gov/WDF/index.htm.
Thanks to Ottawa Fire Safety Officer Peter McBride and Ottawa Fire Lieutenant Kevin Lambert for their assistance.
Peter Hunt, a 29-year veteran of the fire service is a captain in the Ottawa Fire Department’s suppression division. He can be reached at firstname.lastname@example.org