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Fighting Against the Wind

IN APRIL, two Houston firefighters lost their lives fighting what had started as a one-alarm house fire. The National Institute for Occupational Safety and Health is currently investigating what caused their deaths, and one of the things they’re taking a look at is whether that fire was wind driven.

A wind-driven fire is one that is propelled by the wind conditions outside, particularly in cases of open or “failed” windows. The ventilation increases the fire’s heat production and rapidly forces the fire and gases out of the fire room and into any available pathway.

“If there’s a wind present, it turns the fire into a blow torch when we begin our attack,” describes Jerry Tracy, New York City Fire Department (FDNY) battalion chief. If an apartment with a fire has an open door and also has broken windows that let the wind in, firefighters who enter the hallway of the apartment building on the floor where the fire apartment is located can be killed on the spot even though they are not yet at the fire apartment, because the heat and gas travel so quickly down the hall. Winds as low as 10 or 20 miles per hour are enough to generate wind-driven conditions.

Two recent reports by the National Institute of Standards and Technology (NIST) take a look at the effects of wind-driven conditions on high-rise fires, focusing on various firefighting tactics and three types of tools that can mitigate the effect of wind. The tools, which were described by Matthew Harwood in the October 2008 issue of Security Management, are positive pressure ventilation (PPV) fans, which can be used in stairwells and corridors to keep the wind-driven smoke and heat out and provide a safe haven; wind control devices, which are blankets and curtains lowered over the failed window to block the wind and return the fire to normal conditions; and floor-below nozzles, which are angled hose nozzles that enable firefighters to spray water through the window from a lower floor and decrease the thermal conditions where the wind is entering the building.

The tools and techniques were tested on buildings in Toledo, Ohio; Chicago; and Governors Island, New York. The researchers also completed laboratory experiments.

Now that the experiments are over, NIST has issued instructional DVDs that explain the findings of the studies and offer tips.

Although the reports focus on high-rise fires, the lessons learned from this research are important for all firefighters operating under wind-driven conditions, experts say.

The “most beneficial thing for fire departments everywhere is pointing out that fire departments need to consider wind in the size-up of any structure fire they have,” says Daniel Madrzykowski, a NIST fire protection engineer who served as one of the lead researchers in the experiments.

One way to know whether a fire is wind driven, according to the report and DVD, is that there are pulses of fire and smoke falling from a window. One of the reasons this research is so important is that some of the findings show that proper wind-driven tactics go against longstanding tenets of fire training. For example, Tracy says, firefighters will traditionally attempt a direct funnel attack by bringing a hose straight to a fire. In a wind-driven fire, that strategy could result in multiple firefighters being burned, because the wind is pushing the heat out into a hallway.

Now firefighters are being told that before entering a fire apartment or a hallway from a stairwell, they should check the door temperature with either a thermal imager or a hole poked in the door to see whether the conditions indicate a possible wind-driven fire (increased amounts of smoke and heat pushing at the sides of the door). If so, then alternative strategies should be employed, such as fighting the fire from the outside. (In a high rise, this might mean using a floor below nozzle.)

In the DVD, Tracy explains that firefighters don’t normally fight from outside, thinking it will increase pressure and push the fire. But in a wind-driven condition, the wind is already pushing the fire out, so water will help decrease the fire and heat.

Another integral aspect of fighting wind-driven fires for firefighters is to be aware of the pathways they are creating. Instead of routinely keeping the fire apartment door open to have a way out, they should be aware that that could be creating a new pathway for the fire and putting lives in danger.

Members of the FDNY participated in the NIST research, and the department conducted its own pilot test on the new tools. Tracy says the department was pleased when it used the wind-control devices in recent fires where windows failed; no injuries occurred. He also says the use of the PPV fans will now be routine.

The Delaware City Fire Company in Ohio does not deal with buildings much taller than five stories, says firefighter and paramedic John Hall, and they’re not planning on buying the devices mentioned in the experiments. But Hall has viewed and ordered the DVD and plans on using it in training.

One of the reasons the DVD is so compelling, according to Hall, is that it shows multiple fires, as well as apartments furnished like normal apartments, making the “fire loads” realistic.

The DVDs are available through the NIST and U.S. Fire Administration Web sites and include videos of the experiments, copies of the full reports, and a PowerPoint for training purposes.