By Captain Craig Nielsen, Los Angeles Fire Department
As a 28-year veteran of the fire service, I've been involved in flashover survival trainings since 1998, and I wanted to take this opportunity to address the phenomenon. What is it? Why are so many occurring? How can firefighters identify them, and what steps can firefighters take to make sure they are safely managing them?
These are just the basics – I'll go into more detail in a free "Understanding Flashovers" webinar sponsored by Draeger Safety, on November 10, 2011 at 8 PM EST. Firefighters and chiefs interested in participating in this educational session can register at http://draegerfiresafety.com. We'll also have a live Q&A so your specific questions can be addressed.
Flashover Defined
There are many different definitions of flashover. Walton and Thomas define it as "the transition from a growing fire to a fully developed fire in which all combustible items in the compartment are involved in fire" although the definition that makes the most sense to me is “the stage when contents and gases are heated to their ignition temperatures and flames break out almost all at once." This is the most dangerous stage of fire development and it kills more firefighters than anything else.
Increased Occurrences
Flashover exposure has increased and here are some reasons why:
• Better turnouts. Firefighters are putting themselves in harm's way unknowingly because firefighters are so well encapsulated.
• Better insulation: Homes are better insulated which is great for the heating bill, but not so great for firefighters. Thermal feedback will occur more rapidly.
• Combustible items: Plastics and synthetics will create a lot more BTUs. Knowing what you’re going into, even looking for signs outside of the building, will help you prepare for what you'll encounter inside.
Warning Signs
Flashovers have signs and symptoms. These are typically things that we can see and identify, such as:
• Heat build-up. When the fire is low in intensity and spreading slowly, combustibles and flammable gases are heated to the point of ignition.
• No visibility. You can go into a structure and see from one end to the other, not knowing accumulated gas in the ceiling space above may be ready to ignite.
• Rollovers. These are the preemptive signs that a flashover is going to occur. If you witness rollover, cool down those gases effectively and get out of the building.
• Pressurized smoke. If you are observing smoke exiting the exterior of a structure, look for what kind of pressure buildup is associated with that smoke.
Safety First
In order to have the most success in a flashover, there are a few steps to keep in mind:
• Two in – Two out. Flashover can cause disorientation and panic. Work in teams.
• Secondary means of egress. Determine another way out before you even go in.
• Facepipe and full PPEs. This is the best protection for any firefighter.
• Risk vs. Gain. Establish what you're risking going into the structure and if it is worth putting yourself in harm's way by going in.
Knowing the warning signs of flashovers is crucial for all chiefs and firefighters, and I'm proud to raise awareness of the indicators to help firefighters avoid injury or death. Don't forget to join me on November 10 for more information.
Craig Nielsen, a 28-year veteran of the fire services, is a Captain with the Los Angeles Fire Dept. He has served as a Live Fire Training Officer, Driver Training Instructor, Career Guidance Counselor & Instructor of Record. Nielsen has been assigned to the most active fire station in the country for over two years, with 20+ responses per day. He is a California state-certified Fire Instructor and Fire Officer, and Emergency Medical Technician. He has been a Dräger Swede Survival instructor since 1998.
