According to the National Fire Protection Association (NFPA), the death rates for three major causes of firefighter fatalities operating in structure fires have been rising. These causes are firefighters becoming lost inside fire areas, firefighters caught by fire progress and firefighters being trapped in structure collapses. These three events can occur when firefighters vent fires before hoselines are ready to operate and when firefighters search superheated fire areas without the protection of hoselines.
This column is the first of two that provide an analysis of factors that affect the firefighter death rate in structure fires.
Vertical venting – opening skylights, scuttle covers and bulkhead doors over stairways – to let smoke, heat and fire rise upward through a roof outlet – and horizontal venting – opening windows and doors to let products of combustion be released outward through those openings – are important firefighting tactics.
There are several reasons why venting is important: venting, whether vertical or horizontal, removes toxic gases from a fire area and saves lives; vertical roof venting channels the spread of fire upward out of a building, instead of having the fire mushroom horizontally into adjoining spaces (for example, vertical roof venting of a store can stop, divert or mitigate an explosion, letting the blast vent harmlessly upward); and the most frequently performed venting at a fire is intended to release smoke and heat to assist firefighters advancing a hoseline.
These venting actions are meant to let products of combustion be pushed out ahead of firefighters by the force of a hose stream. However, bad things can happen when you vent. Sometimes, if you vent before a hoseline is in position and ready to extinguish a fire, air rushing in may increase the size of the fire, making it more difficult to extinguish; a flashover may occur, trapping firefighters in another room who are searching without the protection of a hoseline; and sometimes, if you vent a window and a strong breeze pushes the fire and heat back into the building, you may create a “wind-driven fire,” making it impossible for firefighters to advance the hoseline and extinguish the fire. A wind-driven fire can occur when a window is vented before a hoseline is discharging water on the fire area and the door to the fire area is open. A strong, steady wind that is blowing fire back into the path of firefighters who are about to advance a hoseline prevents them from moving toward the blaze.
When a firefighter vents a window or door (horizontal venting), this action has a 50-50 chance of being successful. It depends on the direction of the wind. Vertical venting is different. Vertical venting of roof skylights, scuttle covers and bulkhead doors is effective 100% of the time. Smoke and heat rise out of a vertical vent because of convection currents, not wind. Hot air (smoke) expands, becomes lighter than air and automatically rises up out of the roof vent opening. Vertical venting in low-rise buildings need not be coordinated with the advance of a hoseline because there is no danger of creating a wind-driven fire when you are opening a roof skylight, scuttle cover or bulkhead door over a stair. The only factor that must be considered when performing roof venting is flame entering a nearby window in an exposure building.
Searching without a hoseline
The performing of horizontal venting of windows and doors should be coordinated with the advance of the hose team. When firefighters enter a fire area to search and vent before a hoseline is ready, they risk becoming victims, instead of rescuers, because venting may suddenly increase the size of the fire or create a flashover or a wind-driven fire.
Venting windows and doors before a hoseline is operating is not a good firefighting tactic. When there is no known trapped victim – that is, no one is actually seen or heard calling for help – venting a fire room or apartment should be delayed until firefighters have the hoseline ready to advance. When the hose team starts to move in, all openings – windows and doors – should be vented immediately, starting with ones that are closest to the fire origin, if possible. Outside window venting should be carried out swiftly and completely; window venting from the inside is done by firefighters as the hose team moves forward. Search and venting can be done quickly, but stretching hose is slow, difficult and labor-intensive work. Testing a hydrant, connecting to the continuous water supply, pulling several hundred pounds of hose to the fire, removing the kinks and supplying the required pressure and volume to the nozzle takes longer.
In the past, before firefighters had the personal protective equipment (PPE) they have today, venting was most often coordinated with advancing a hoseline at a serious fire. With the exception of small fires like those caused by “food on the stove” or fires involving mattresses, sofas or chairs, which could be controlled with a portable extinguisher, firefighters operated close to the hoseline when searching and venting. Before firefighters were assigned radios, firefighter on front fire escapes would time their venting by looking down in the street for the hose jumping and twisting under pressure; at night, they would listen to the sound of the hoseline hissing when water pressure was delivered by a pump operator.
In times past, the saying for inside venting was “Vent as you go,” which meant vent as you proceed with the hoseline. Firefighters were not advised to search and vent at a serious fire before a hoseline was operating. And statistics indicate firefighters were not caught and trapped by fire and smoke as often as they are today. This is one of the few causes of an increase in firefighter deaths at structure fires. In the past, firefighters might have been killed by collapses, explosions and carbon monoxide and smoke inhalation, but not as often by being caught and trapped by fire. When firefighters search and vent along with a hose team that is discharging 180 gallons, or three-quarters of a ton, of water per minute, they are not caught and trapped by fire or flashover.
Some studies of firefighters caught and trapped by combustion products reveal they were searching a fire area where there was no protective hoseline operating. When it is necessary to perform a high-risk search before a hoseline is operating, there should be a known life hazard at risk. A trapped person must be seen or heard calling for help; firefighters should not be put at risk based only on a report of the possibility of a trapped victim. Too often after a mishap, the statement is made, “there was a possibility of a trapped victim.”
At a fire at which there is a confirmed person trapped and in danger, all efforts should be made to rescue the person. At such a situation, venting before a hoseline is in place is acceptable if it is believed it could help save the victim’s life. However, this life-and-death situation does not exist at most fires. In fact, it is very rare. And most studies have shown that at fires where firefighters were caught and trapped by fire, in reality nobody was trapped and no victims were found.
Venting to save lives
When you vent a window from the outside with the purpose of saving the life of a known victim before the hoseline is advancing, you must then enter the window and rescue the victim. You cannot just vent a window from outside a building to save a life, then go to the next window to vent it. You must enter the smoke-filled room and get the trapped victim.
There is a belief that simply venting all the windows of a fire area will save the lives of victims who are trapped in smoke. This is untrue. Venting windows before the hoseline is ready and then not entering the vented window and searching for a known victim will do nothing but spread the fire. Any possible victims would be burned to death instead of asphyxiated. If no hoseline is being advanced and you vent a window or door from the outside, you will feed oxygen to the fire and increase fire growth and temperature and possible trigger a flashover or a wind-driven fire. n
Next: Fire-growth factors
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VINCENT DUNN, a Firehouse® contributing editor, is a 42-year veteran of the FDNY and a deputy chief (ret.), serving as a division commander for midtown Manhattan. A nationally renowned lecturer, he is the author of the best selling text and DVDs Collapse of Burning Buildings and textbooks Safety and Survival on the Fireground, Command and Control of Fires and Emergencies and his new book Strategy of Firefighting – How to Extinguish Fires. Dunn has a master’s degree in urban studies, a bachelor’s degree in sociology and an associate’s degree in fire administration from Queens College, City University of New York. He can be reached at 800-231-3388 or at email@example.com.