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UL tests transitional attack for house fires
Excerpts from the ChicagoTribune.com:
On March 18, over 100 firefighters from the U.S. and Canada gathered at Underwriters Laboratories in Northbrook to explore new, safer strategies for tackling residential fires. The event focused on a technique known as the "transitional attack," which combines exterior and interior firefighting methods.
Steve Kerber, director of UL’s Firefighter Safety Research Institute, explained that traditional fire suppression methods often involve rushing in with hoses and attacking the fire room by room. This approach can be dangerous, as it may push flames into other areas and cause superheated steam to harm occupants. Instead, the transitional method involves first attacking the fire through windows before moving inside.
Kerber emphasized that the goal is not to dictate how firefighters should act, but to provide them with more options. UL has conducted this type of test about two dozen times in the past month as part of a three-year study funded by a $3.5 million U.S. Department of Homeland Security grant.
During one demonstration, a team of UL firefighters attacked two burning rooms through open windows, spraying water upward to avoid spreading the fire. They then swept the area in a circular motion to minimize air intake. Within 15 seconds, the flames were gone, and temperatures dropped from 1,800°F to 250°F. When they entered, only a small spot on a chair remained.
However, the method isn’t foolproof. Northbrook firefighter Lt. Ryan Lee pointed out that if windows are closed, breaking them could introduce oxygen and worsen the situation. Kerber said that in such cases, firefighters should go inside if enough personnel are available. Otherwise, breaking a window might be the best option.
One of the main benefits of the transitional attack is that it reduces the time firefighters spend inside a burning structure, which is critical for their safety. Lionel Crowther, a senior firefighter from Winnipeg, shared his personal experience after being severely burned in a 2007 fire that claimed two lives, including one he couldn't save.
UL’s research includes testing the effects of heat on human skin using hogs and rats, providing valuable data on fire behavior. Gavin Horn of the University of Illinois Fire Service Institute noted that the myth about water increasing the steaming effect was largely unfounded, as fires themselves produce significant moisture.
The event was closely monitored via eight cameras, capturing every detail of the controlled burn. A fire was started with a dropped match, and firefighters were called in after several minutes. Kerber explained that flashover—when everything in a room ignites—typically occurs within four minutes. However, many departments arrive too late, often after seven minutes have passed.
While the demonstration offered important insights, some firefighters felt it didn’t fully reflect real-world conditions, especially in larger homes with more open spaces. McCulloch pointed out that in wealthier suburbs, where houses are bigger and more open, firefighters may have no choice but to enter early.
Ultimately, the message was clear: closing doors when evacuating can significantly reduce fire spread. As Kerber said, “When they leave the house, they should close the door.â€