They say you can’t fight fire with fire, but maybe you can with wind.
Positive Pressure Ventilation has been used around Iola for about 15 years, said Deputy Fire Chief Tim Thyer. Now, it’s being used in a different way. Once just a means of clearing smoke from buildings, the system incorporates a high powered fan. As long as there is a good vent for smoke and flame to exit, it’s been discovered the fans can be used to dramatically reduce room temperature, clear smoke so fire fighters can enter and even direct flames away from undesired areas.
Thyer, Fire Chief Don Leapheart and Deputy Chief Norman Mullins all attended a one-day class to learn to use the new technique.
“It was good training,” said Thyer.
Held at Labette County Community College, the program was sponsored by the University of Kansas for area firefighters. Leapheart learned of the class through a Southeast Kansas fire chiefs meeting. What they learned surprised them.
Firefighters, the men were told, suffer from certian cancers at rates far above the general public.
Prostate cancer rates are 28 percent higher in fire fighters, non-hodgkins lymphoma and myelomas are 50 percent higher and testicular cancer rates are 100 percent higher than those in men not regularly exposed to smoke.
Thyer and Leapheart described how for days after a fire, you can smell smoke coming from your pores.
“That correlates to why this thing is becoming big,” Thyer said of the new ventilation method. “We’ve always worn self contained breathing apparatus, so our lungs were not an issue. But we never thought about absorption through the skin.”
In 1970, Thyer said, the time it toook for a fire to spread to the point where everything in a home was burning — flashover — was typically 14 to 15 minutes. Now, due to the presence of so many hydrocarbon-based products in our lives, flashover comes in three to four minutes. It takes that long for firefighters to get to a scene, said the men.
“We’re arriving at the most volatile part of a fire,” Thyer said — and the point where the most toxic fumes are being released into smoke.
In a typical fire, Thyer said, air enters a house through one opening, while fire exits another. Once a fire is put out, firefighters push out the remaining smoke with a high pressure fan.
“What the fan does is create positive pressure in the building,” Thyer said. “Outside is negative pressure. Fire and smoke are attracted to negative pressure.”
It was always thought that adding fans to an active fire would cause an increase in flames. What a group of firefighters in Utah learned was, by pointing the cone of wind from the fan in a certain way into the structure as it burns, you can push the smoke out ahead of the firefighters’ entry and direct the flames’ path.
“You let that fan work for 60 seconds,” Thyer said. “During that time you advance your hose line, and you’ll have a clear view to your fire source.”
Previously, firefighters had to belly-crawl through the smoke and feel around in the dark to find the flame source. “It also reduces stress and anxiety,” Thyer said.
“If you’ve ever crawled around in a burning building,” Leapheart said, “it’s nerve-wracking. You don’t know what you have until you put you hand on it.”
Without smoke occluding their view, firefighters can enter on their feet instead of crawling, Thyer said. “You can follow the bank of smoke to the fire. You can stand to carry in your gear, and visibility is better.” Those aspects reduce response times — and could save lives. Plus, he said, “if you have an exit or window open in the building, the mortality rate for anyone trapped inside decreases 50 percent.”
You can also direct the flames somewhat, Thyer said. “There will be a direct line of fire from the place of the fire to the place of exhaust.” That means in an attic fire for example, the flames can be directed out a window, rather than spreading throughout the structure.
“Positive ventilation has always been there; it’s just a new method of using it,” Thyer said.
A video demonstartion by the Chicago Fire Department notes a reduction in room temperatures where PPV is used from 650 degrees to 60 degrees in 30 seconds. That could definitely save lives.
“We haven’t had a chance to try it yet,” said Thyer, “and I don’t want to have to, but the next structure fire we have, I’m using it.”
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