FEWER FIRES, BUT MORE FLASHOVERS

BY TOM BRENNAN

I spend a lot of time chatting with firefighters around the country like yourselves in person and through the Internet. On various Internet sites related to the fire service, I have seen posted an unusual number of firefighter injuries and worse from conditions assessed as flashover. “Why are there so many flash-over events today as opposed to yesteryear when there were twice as many structure fires?” one firefighter asked me. Let’s review what I think accounts for this “phenomenon,” and perhaps our leaders of today could address some of the problems without resorting to a no-go strategy.

First, we have faster-burning and hotter fires in today’s fire experience than in the past. If you took a pound of “stuff” from the interior of yesteryear’s occupied structure-which may be made up of music devices, drapes and rugs, door and cabinet assemblies, telephones, and tubs and toilets-and put it in a box and burned it to complete combustion, you would have gotten only 8,500 Btus per pound from the process. If you take the same functional items from today’s occupied dwelling and burn them in the same box, you will generate 17,000 Btus per pound-and in a faster time frame.

The second factor involves building construction trends and changes in the building codes and regulations. Today’s buildings are erected with materials that perform according to load and function requirements. Floors are assigned minimum load bearing criteria and not a specific construction criteria. Codes no longer state the material from which a structural member must be made; anything that performs is okay. The regulatory services became too weary of spending time in court with variances to the specification codes of old-hence, truss lofts, plastics, combustible rubber roofs, and the like. Safe and usable fire escape assemblies required too much maintenance, and the code officials were forced to remove them from existence, much to the detriment of inner-city structure firefighters.

Third, Americans have a love affair with security! And no one blames them. Drugs have made every town in America filled with buildings that have become vaults. Steel plating, concrete block, PlexiglasT, roll-down metal shutters and doors, multilocking devices, and resealed openings on roofs are just a few of the trends that prevent the fire from venting itself earlier and, more importantly, slow the fire attack team. Remember, the way to prevent flashover is to cool the heating process and then the fuel around it. If you cannot get to the site of flashover with sufficient tactics to accomplish those tasks, you increase the possibility of flashover.

Ventilation of the rear of a one-story commercial occupancy is the critical task you must accomplish for the cooling effects of a rapidly advancing handline to prevent flashover. Now you find a fortress there with not enough personnel or logistics to effect that horizontal opening.

Fourth, energy-conscious Americans have tightened up the buildings. The pressure of interior fire buildup is not able to easily cause fracture and failure of some enclosures such as windows and doors. Thicker walls filled with insulation materials and windows of double and triple pane glazing are contributing to heat buildup, causing materials within the building to heat to ignition temperature and then to flashover. Ventilation by the “too few responders” is most often ineffective because of the failure to “take all the panes of glass.” Remember, ventilation is making an opening from outside to inside where the fire “lives.”

Fifth is a “damned if you do and damned if you don’t” phenomenon. Simply said, you get to the scene earlier. Flashover could have occurred in the old days, and buildings could have vented themselves to the outer air because of the usual delay in discovery. Now with automatic alarms and smoke detectors (a great thing for the life safety of America Burning’s civilian population), you arrive at the “envelope” that has not yet vented itself.

Also consider that in the past firefighters had to vent the structure just to get into it with their poor outer protection and lack of breathing devices. Today, that ventilation is not required according to some of our salvage-conscious leaders. “We don’t need that opening up any more,” one told me from the middle of the classroom. “You are right,” I said, “but the fire needs the vent!”

The final factor is the murderous effects of not enough people showing up at structure fires to perform the CRITICAL TASKS necessary to prevent flashover from occurring. You simply cannot “trickle” in the task performers of a building on fire. You cannot stage crews until some vested person decides what tactic is next on his waterproof checklist. You cannot afford to have teams of three, four, and even five firefighters performing the same single extinguishment support tactic-truck work! And you cannot have hoselines move fast enough above the first floor with only two firefighters on the entire line (and one is the officer).

TOM BRENNAN has more than 35 years of fire service experience. His career spans more than 20 years with the Fire Department of New York as well as four years as chief of the Waterbury (CT) Fire Department. He was the editor of Fire Engineering for eight years and currently is a technical editor. He is co-editor of The Fire Chief’s Handbook, Fifth Edition (Fire Engineering Books, 1995). He was the recipient of the 1998 Fire Engineering Lifetime Achievement Award. Brennan is featured in the video Brennan and Bruno Unplugged (Fire Engineering/FDIC, 1999).

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