Friday, November 22, 2013
Most know that at 212 degrees F, water will boil. At 350 to 450 degrees F, food will cook nicely. Both will burn humans. What happens at 1,000 to 1,500 degrees F?
That is the temperature for what fire science calls a flashover – the point when everything in a space reaches ignition point, including the smoke and ignites at once.
It will kill.
It kills many firefighters every year.
Firefighters need to be trained to recognize the signs that a flashover is imminent and that they need to get out, know that when searching a space how far they can go in order to be able to get out should a flashover be imminent…all fine in theory but it is one thing to listen and watch a video and quite another to experience the phenomenon first-hand.
For three days, everyone on duty on all shifts got the chance to suit up and go inside a flashover trailer in about 700 degrees and sit there while the space filled with dense smoke and, suddenly, everything gets dark then…whoosh…fire overhead, all around...flashover.
This is crucial training, says Training/Fire Prevention Coordinator Cpt. Jacob Evans.
“It teaches fire behavior, how to recognize pre-flashover conditions.”
“This is the first time we have ever done this in Summerville, says Fire Chief Richard Waring. “Our goal is to teach what it looks like and how to stop one.”
It isn’t, continued Waring, about putting the fire out but to experience the phenomenon.
“We are really excited to be able to do this,” says Evans, “it’s a really big deal, a big event.
The fire department invited town council members to come watch the training and see funding at work but none were able to attend.
Firefighters spent about a half hour in classroom prep, watched a video, asked questions and heard what would happen. They are told never to go further than five-feet from a means of egress, in a straight line, because with all their gear on they can only move two feet per second. They are told that no one can survive more than two seconds in a flashover situation that generates temperatures as high as 1,500 degrees.
Then they suit up. While firefighters were in the classroom, the instructors have prepped the trailer.
The training is taught by instructors from Brown Emergency Training Center of Cleveland Community College in Shelby, NC. These trainers do trainings all over the southeast, they said.
The trailer is a bi-level metal box-style custom-made trailer. The upper level has a series of chains that hold particleboard against the roof and walls, simulating structure ceilings and walls. Also on this level is a 50-gallon drum holding cut up wooden pallets and stuffed with newspaper.
After putting on their gear, the firefighters check the Scott Air-Paks only to discover most are empty. A brief delay while they each fill their air paks, check the mask fit and then enter the lower level of the trailer, single file, with the instructions “one cheek on, one off” the narrow wooden bench that sits about 12 inches off the floor. Short of lying on the floor, this is as low as they can get. The higher they sit/stand, the hotter the air temperature.
There is an EMS bag and defibrillator sitting near the training site…just in case.
Last minute instructions are given and one of the instructors begins to light the newspaper on fire, using a blowtorch.
Soon smoke is emitting from the barrel, then flames. The doors to the outside are shut, allowing fumes, smoke and gasses to build up inside. There is a tiny square cutout at the back end of the lower level through which a two-inch charged hose runs. This is to dampen the fire allowing multiple flashovers for training.
Soon, the smoke is so dense the firefighters can barely see their own hands in front of their faces. It is almost as though there is no fire, when suddenly, overhead, flames shoot along the ceiling. By now it is hot outside the small hole through which brown smoke pours. Smoke billows from cracks in the trailer and through a chimney. Occasionally flames can be seen outside.
After a number of flashovers have been allowed to take place, as firefighters rotate their seating positions so all experience close proximity to the source of the fire, the doors open and they come out, sweaty, but grinning.
“We usually go in to a fire before or after a flashover,” says firefighter Brent Melcher, “to see it from beginning to end like that is pretty neat to watch.”
And says Cpt. David Headden, …“It was pretty warm in there.”