Editor`s note: This article is based on a research paper the author submitted in September 1998 as part of the "Strategic Management of Change" course in the National Fire Academy`s Executive Fire Officer Program.
We thank Chris Kozub for his comments (Letters to the Editor, September 1995) so we can clarify some issues we may not have made clear regarding how the Rockland County Fire Training Center conducts the Flashover Survival Program.
The flashover simulator is a training unit designed by the Swedish National Survival Board in 1986. It is the first segment of a four-stage firefighting system. This first stage involves trainees as observers only; subsequent stages take firefighters through practical, hands-on suppression methodologies. This article covers only the first stage of the Swedish system.
The call was for a basement fire in a three-story brick multiple dwelling. The first-in engine transmitted the signal for a working fire. Two additional engines and a truck were dispatched. Engine 8 arrived third. The intense heat prevented the first two engines from moving into the basement. Engulfed in the hot, black, billowing smoke, they applied water into the opened exterior cellar door.
Flashovers have been happening in North America since 1590, but they seem to be having a more adverse impact on firefighters now than ever before. One of the reasons for this is lack of experience. Most firefighters rarely get to see a flashover. Either they arrive in time to keep it from happening or they arrive after it happens Unfortunately for some firefighters, the first flashover they witnessed was also their last.
Flashover—sudden fullroom involvement in flame —is the most dangerous stage of fire development. It can trap and kill firefighters. Flashover is caused by thermal radiation feedback. During a fire in a room, the heat is absorbed into the ceiling and upper walls and reradiated downward, gradually heating the combustible gases and contents of the burning room.
Flashover can be described as the instantaneous ignition of a large area of combustible materials. This “area” may be a single room, a large indoor area, or even a narrow canyon. The important aspect of flashover is that the space must be contained enough to accumulate heat through any combination of convection, conduction, and radiation for the combustible materials within to reach their respective flash points (in the presence of an ignition source) or ignition temperatures.
Flashover has been around since people began filling up semitight rooms with combustibles, but it was not until the mid-sixties to early seventies that we began to identify it as such. There’s a lot we still don’t know about it; in fact, there isn’t a concensus, standard definition of this deadly fire occurrence. Some express it in terms of thermal radiation feedback; others see it as a pivotal point in a fire’s growth; still others have attempted to describe it in terms of temperature over time or as a function of burning rate, room geometry, and ventilation.
RECENTLY THERE has been a rash of incidents across North America involving the fire phenomenon of flashover. Unfortunately, the fire service has lost and the fire has won in most cases. In order to discuss this event in a fire's development, some definitions should be reviewed.
In this series of spectacular photographs, Robert Stella captures the phenomenon of flashover in all its intensity. The members of the Hull, MA, Fire Department narrowly escaped without injury. It is currently believed that flashover is caused by thermal radiation feedback from the heating combustibles within the fire area.