There are three types of burn buildings: traditional, acquired structures and simulated structural fire buildings. Traditional burn buildings, built with special materials, can withstand multiple fires, although they do break down over time. Traditional burn buildings exist in communities, at fire academies and on university campuses. The fuel used to ignite fires in these structures is typically straw, hay or wood pallets.
Acquired structures are condemned houses or other abandoned buildings. Instructors locate a suitable building and begin a tedious process. First, an instructor gets written permission from the building's owner and acquires necessary permits and health clearances to proceed. They notify everyone in the surrounding community of the pending burn, including residences and businesses. Instructors make certain there's no insurance or liens on the property to prevent fraudulent claims and legal trouble. With the legal issues out of the way, site preparation begins. Here's how the process works:
- Inspectors approve the building's structural integrity and make sure it's safe for training exercises.
- A crew repairs unsafe conditions such as broken stairs and rotted floors for interior training.
- They remove fuel sources other than Class A. Live fire training only involves ordinary combustibles, or Class A fuels (fabric, wood, paper and rubber).
- A crew member cuts a hole into the roof to channel convection currents out of the structure. When fuel sources burn, they produce gases. Convection happens when these gases move together, creating a wave of heat that moves upward. These currents, if not given an outlet, can make the fire spread or build up, causing a spontaneous explosion called a backdraft.
- They score chimneys near their bases to ensure they fall when the structure collapses.
- The instructor identifies positions on the site for the instructors and emergency medical personnel to safely observe.
- The site is ready for training to begin.
Even with the preparations and precautionary measures, using an acquired structure can still be very dangerous. The fire is controlled, but that doesn't mean it's any less real. From 1994 to 2004, 99 firefighters were killed during training, some of these in live fire training. Statistics like these led fire instructors to adopt a new, safer method for live fire training: simulated structural fire buildings.
Simulated structural fire buildings are far more advanced and rely on computers to control the fire. These burn buildings' computers control built-in fire-producing devices that run on propane and natural gas, and use a non-flammable aerosol to synthetically create real smoke. If there's an emergency, the burn building has systems to extinguish the fire and extract all of the smoke with the push of a button. The computer also lets the instructor choose in how the fire will burn and at what temperature. The computers are capable of simulating fire scenarios for different occupancies in the building, residential or otherwise. They can even simulate inflamed furniture, such as burning sofas or tables.
Engineers design these burn buildings with a variety of materials, including masonry, concrete and metal. The walls and ceilings of the building are covered with heat-resistant tiles with built-in sensors to keep track of the fire's intensity. The roof contains "chop-out panels" made of wood, which gives students the opportunity to learn how to properly ventilate a burning house and deal with major burns to the building's structure. When the training crew applies extinguishing agents, the building has sensors that can tell which one the crew applies and whether or not it has been appropriately applied. The sensors communicate to the main computer how to respond to the crew's method. If a crew inappropriately applies an agent, it will simulate a real-world response.
Specialty firefighters, like airport firefighters, also use this technology in training props. For instance, an airport fire crew may attack flames on a section of an airplane fuselage sitting in a gravel pit. For their prop, the computer controls a system of gas pipes that come up from under the fuselage.
Simulated structural fire buildings are the safest and most durable out of the three burn building options. Conducting live fire training in an acquired structure can be a gamble, because there's no guarantee how long the building will stand. It's common to schedule training in an acquired structure only to have it fail halfway through. Training in acquired structures and traditional burn buildings can also be more labor intensive. If the fire goes out, the crew stops the training drill to reignite the controlled burn. And no matter how durable the materials used in a traditional burn building are, fire is a formidable force and eventually the structure breaks down and becomes unusable.
If maintained properly, a simulated structural fire building can last indefinitely. Also, their durability produces not only better-trained firefighters, but more of them -- a noteworthy advantage over their more primitive counterparts. When instructors don't have to relight fires or spend time acquiring and prepping new structures, they're free to focus on training. Further benefits include significantly reduced air pollution, making it easier to conduct training in populated communities.
But some critics claim that buildings with simulators don't reproduce fires to realistic temperature or magnitude, giving students a false perception of real-world fires. Some of the mechanisms for responding to the application of extinguishing agents have also been criticized for the same reason. Though they are severely limited and hazardous, acquired structures provide the most realistic training experience currently possible.
Volunteers and Ranks
Volunteer firefighters adhere to the same guidelines and requirements that career firefighters do, as outlined by the document NFPA 1001, but in many states and jurisdictions, volunteers aren't required to become certified. Only a minority of volunteers ever make it that far. Most volunteer firefighters work other jobs and can't devote full-time hours to training. Instead, local fire departments offer weekly or monthly training events to ensure everyone develops the skills they need. Other than in the state of Florida, volunteer firefighters aren't restricted from any firefighting tasks. Some departments consist entirely of volunteers, including the truck drivers, called engineers, who often have experience driving big rigs or school buses. In addition to driving, engineers operate the hose pumps.
For a career firefighter, becoming an engineer is a first-level promotion in the department. Firefighters are usually eligible for such a promotion after a few years of working for the department. It is then up to newer crew members to battle the blazes. From there, one can move up the ranks of the department. Standard ranks go as follows:
- Battalion Chief
- Deputy Chief
- Assistant Chief
For more information on firefighter training and related topics, check out the links on the following page.
Related HowStuffWorks Articles
More Great Links
- Rafilson, Fred. (2003) Firefighter 14th Edition: 1-53.
- NFPA 1403: Standard on Live Fire Training Evolutions. http://www.ci.yakima.wa.us/services/fire/NFPA1403.pdf
- Masi, Mary. (1998) Firefighter Career Starter: Finding and Getting a Great Job. New York: Learning Express.
- Campbell, Colin A. "Burn Building Basics." February 15, 2006. http://firechief.com/news/firefighting_burn_building_basics/index.htm
- United States Fire Administration. "Firefighter Fatalities in the United States in 2004." http://www.usfa.fema.gov/downloads/pdf/publications/fa-299.pdf
- White, Clarence. "Conducting a Safe Structural Burn Training Drill". February 15, 2006. http://cms.firehouse.com/content/article/printer.jsp?id=39285
- Brady, Don T. (2003) Carolina Fire Rescue EMS Journal. "Gas-fueled, computer-controlled, systems: Delivering Safe, Live Fire Training." http://www.kiddeft.com/Article_Delivering_Safe.shtml
- Colletti, Dominic, and Davis, Larry. "Calculated Risk." February 15, 2006 http://firechief.com/mag/firefighting_calculated_risk/index.htm
- Pikulsky, Jeff. (2003, August 18). "Burn Building' unveiled at Cal U." The Valley Independent: PittsburghLIVE.com. http://www.pittsburghlive.com/x/valleyindependent/news/s_150478.html
- City of Denton Fire Department: Fire Extinguishers http://www.cityofdenton.com/pages/fireextinguishers.cfm