DANGERS OF HIGH-RISE FIREFIGHTING
BY VINCENT DUNN
New York City: Two firefighters are killed by toxic gases 20 stories above a cellar fire in a high-rise building.
Chicago: Two firefighters plunge 15 stories down an open elevator shaft in a high-rise fire.
Philadelphia: Three firefighters are trapped and killed while searching above a spreading high-rise fire.
As these deaths testify, high-rise firefighting is extremely dangerous. Normal dangers at a high-rise fire include flame, smoke, heat, toxic gases, flashover, backdraft explosions, and flameover. The high-rise building itself presents other dangers in terms of structure, building systems, and floor design, to name a few.
Following are some firefighting dangers found in high-rises and some safe firefighting procedures to help you survive a high-rise fire.
Heavy pieces of razor-sharp broken window glass falling into the street from 10 or 20 stories above can cause injury and death. Falling glass can strike people standing on the sidewalk who have just been evacuated or rescued from the building, people who have come outside to watch the firefighting operations, and working emergency personnel.
The glass used in a high-rise building is more deadly than glass from a residence building–it is thicker and heavier. Glass 14-inch thick weighs 212 pounds per square foot, while glass 12-inch thick weighs five pounds per square foot. So a large eight-foot by four-foot section of 14-inch-thick glass weighs 80 pounds; a 12-inch-thick section of glass the same size weighs 160 pounds, and if you break out such a window in a high-rise building during a fire, four 40-pound glass shards could rain down on firefighters and civilians in the street. One of the first lessons a firefighter learns when he transfers from a residence building district to a high-rise district is that you don`t vent windows because it is too dangerous–not because the chief doesn`t want you to. Most of the windows are sealed shut or require keys to open.
You can break a window in a high-rise fire to vent heat or smoke in some circumstances–for example,
if there is a balcony or setback around the high-rise that will prevent glass from falling to the street;
on the side or rear of the building if the glass will fall onto the roof of an adjoining building; and
during nighttime or early morning operations after the fireground commander has a company shut off the street and sidewalks at both ends, posts firefighters in doorways to prevent people from walking out of buildings into the danger zone, and gives permission to vent.
Venting sealed windows to release smoke and heat must be limited and strictly controlled. It is not done at all at most high-rise fires because it is too dangerous. The accepted rule is that you fight a high-rise fire like a cellar fire.
Taking an elevator up to a fire is the most dangerous part of high-rise firefighting. Elevators can bring firefighters up to the fire floor and discharge them into a flaming lobby; or, elevators may get stuck in a shaft above a fire and kill firefighters in a chimney-like flue.
An officer recently told me of an elevator mishap he responded to at a high-rise residence fire. The computer hard copy stated fire on the 13th floor. The dispatcher`s radio message received en route confirmed the 13th-floor fire. At the scene, the officer`s company entered the elevator and pressed the button for the 12th floor. The elevator ascended; the door opened; and flame, heat, and smoke filled the car. The firefighters inside dropped to the floor, put on face masks, and hit the buttons for lower floors. Nothing happened. They held the doors closed. The officer said he heard the hose attack team advancing a stream down the public hall to the right. He told his personnel to get ready to scramble out of the elevator to the left. Suddenly, the elevator descended.
The officer said he learned the following lessons:
You had better know the correct floor of the fire. The hard copy and radio report were incorrect. The fire was on the 12th floor, but it was reported by a person on the 13th floor.
Take the elevator two floors or more below the reported fire floor. One floor below is too close a call.
In another near-death mishap at a major high-rise fire in 1993, an inexperienced firefighter was assigned to operate the elevator during the height of the fire. He took a company above the fully involved floor to search the floors above. On his descent after the search and rescue team left the elevator, the car got stuck in the shaft on the floor above the fire. The firefighter trapped in the heat- and smoked-filled elevator called for help. Searching firefighters heard his cries and saved his life.
The lesson here is, never take an elevator above a fire if it is in a shaft that opens on the fire floor. A blind shaft, one that does not have an opening to the burning floor, may be used during the fire`s early stages. However, use caution even in a blind shaft because modern high-rise structures use two-inch gypsum block to enclose elevators. A powerful master stream could knock a hole in such a wall, making a blind elevator shaft an open elevator shaft, which possibly could expose the floor above to heat, flame, and smoke.
If the fire is below the sixth floor, walk instead of taking an elevator; or, take a low bank elevator that does not reach the fire floor, and walk up. It is safer.
At the 1 New York Plaza high-rise fire in New York City in 1970, the major structural damage was floor collapse. Twenty thousand square feet of concrete and steel floor deck and 150 steel floor beams were replaced. The fire caused the floor above to buckle, crack, and heave upward. Floors and partition walls were slanted upward and sideways. No floor slab collapsed, but firefighters could not safely enter the floor area that was cracked and buckled upward because of the collapse potential.
The floor of a skeleton steel-frame high-rise structure is usually corrugated steel 10-foot by 12-foot sheets covered with two or three inches of concrete. This combination steel and concrete floor deck is supported by steel beams in a gridiron design. When the heat from a fire destroys the ceiling and heats up the underside of a floor`s corrugated steel, the section of concrete above will crack at the seams and buckle upward; then, a section of floor will sag as the steel beams below also warp, twist, and buckle.
At the Banker`s Trust Company Building fire in New York City in 1993, an officer reported that the floor above the fire he was searching was beginning to buckle and sag. He noticed file cabinet doors suddenly opening. Entire lengths of the file drawers rolled out of the cabinets. After the fire was extinguished, the cause of the file drawers` opening was found to be sagging and collapsing floors. As the steel and concrete sections of floor sagged, cabinet drawers slanted downward and rolled out.
At a high-rise fire in Montreal, Canada, that burned several floors, a 10-foot by 12-foot section of floor collapsed to the floor below. Thus, be aware that a fire-resistive high-rise building can experience fire spread from floor to floor as well as collapse in a fire.
Wall collapse. At the One Meridian Plaza fire in Philadelphia, sections of the granite wall collapsed. Flames spreading upward from window to window on the outside of the structure heated the granite facade. Large chunks of heated granite weighing 20 to 30 pounds came crashing down on the sidewalk, narrowly missing firefighters. (Stone and concrete are subject to spalling–the collapse of masonry sections caused by the expansion of moisture inside the stone or concrete–when heated.)
Ceiling collapse. At a five-alarm fire in 1990 in the Empire State Building, a reinforced concrete and steel structure, pieces of the concrete ceiling collapsed on firefighters advancing a hoseline. If a concrete structure does not have a drop ceiling, its ceiling will be directly heated by fire. Spalling will occur. Chunks of concrete ceiling will collapse on the helmets of firefighters advancing an attack hoseline. Concrete pieces weighing 10 to 20 pounds falling 10 feet can cause serious injury.
Suspended ceiling collapse. High-rises can have lightweight suspended ceilings. A thin metal and wire grid system holds removable panels. If flames heat the supports, the suspended ceiling can collapse. Firefighters can become entangled in the thin metal framework and suspension wire, or in falling electrical conduit, after a collapse, trapping them in a flaming room or hallway. Thus, the injury a firefighter receives from a suspended ceiling collapse may come not from being crushed but from smoke and burns following the collapse. When searching a floor at a high-rise fire, lift a panel of the suspended ceiling with a six-foot pike pole. Fire may be spreading in the space above the ceiling, over your head.
Fluorescent light fixture collapse. Even before spalling occurs, large, heavy, suspended fluorescent light fixtures can collapse during a fire. These fixtures can weigh 20 to 30 pounds and are suspended by wire or chain and fastened into the concrete ceiling by lead fasteners or anchors. The heat from a fire will quickly melt the lead fastenings, and the light fixture can fall. Concrete structures such as public schools, hospitals, and high-rise office buildings have these collapse dangers in their halls.
The floor layout in a high-rise office building–with its large open spaces, long hallways, dead-end corridors, and maze-like puzzle of walls and office work stations–can be a deadly trap for searching firefighters. The floor layout of a 20,000-square-foot high-rise office can make a firefighter`s entry and escape from a smoke-filled area a nightmare. Firefighters must be familiar with the design of a high-rise floor through prior inspection visits or a floor plan. While no two floors are exactly the same, there are general common features. Knowledge of floor layout will give the firefighter confidence and make him more effective when searching in dark or smoke.
General features of a modern high-rise building`s floor layout may include the following:
a central core in the middle of the floor containing stairs, electrical closets, heat and ventilation equipment, bathrooms, and storage rooms;
offices in the floor`s outer perimeter;
small rooms separating the outer perimeter window area from the interior;
cubicle maze-like work stations between the outer perimeter offices and the center core area; and
hallways and corridors located in the middle area.
Dead-end corridors. This is an extension of a corridor or aisle beyond an exit. It forms a pocket in which a firefighter can become trapped. There is only one access to an exit from a dead-end corridor. While moving toward an exit in a smoke-filled high-rise floor, a firefighter may pass the exit door and become trapped in the dead end.
Cubicle maze-like work stations. This is another deadly design for firefighters, who can become disoriented inside the maze-like cubicles in a dark or smoke-filled environment and become trapped by flames.
Search rope. Because of the numerous floor layout hazards mentioned above, firefighters must use a search rope. It will allow a firefighter to retreat safely if smoke or flames suddenly fill up the floor. The search rope–100 feet of small-diameter nylon rope with snap hooks on each end–is used by the first firefighters onto the fire floor when searching for fire origin over a 20,000- to 30,000-square-foot floor area that may contain 150 rooms and work spaces. They secure the rope to a stair banister before entering the floor to search. They then play it out as they get farther from the stairs and closer to the fire`s heat and smoke. When they discover the fire origin, additional firefighters stretching hose as well as the chief can follow the search rope to the point of the fire without delay.
When a fire occurs inside a high-rise building, the smoke is heated. Smoke temperature in the fire`s vicinity can reach 1,200ºF to 1,400ºF. As smoke moves away from the fire, or the so-called “hot smoke” zone, it loses heat. Likewise, when smoke travels up stairs, hallways, and shafts, it is cooled by the entrained air, concrete walls, and ceilings it passes.
In a high-rise, the stack effect moves smoke throughout the structure, into the “cool smoke” zone. The stack effect is caused by temperature differences between the inside and outside of a sealed high-rise building. This temperature difference creates pressure differences inside a sealed high-rise that can move the smoke 10 or 20 floors away from the fire`s origin. The smoke can travel upward and sometimes downward through stairways, elevator shafts, smokeproof stairways, smoke vents, air-conditioning ducts and shafts, utility closets, mail chutes, concealed spaces, and poke-through holes at the outer skin of the curtain wall. Eventually, the smoke stops moving and stratifies somewhere in a remote portion of the building. The smoke stratification can fill five or 10 floors in the middle of a 50-story stairway or fill an office floor 15 or 20 floors above a fire. While this smoke is cool and has lost its heat buoyancy, it is still deadly and may contain carbon monoxide.
Two members of the City of New York (NY) Fire Department were asphyxiated and killed by stratified smoke. Firefighters Charles Lang and Robert Hurst went to search for victims reported trapped on the 20th floor during a fire in a subcellar of a high-rise building and were overcome by carbon monoxide. The lesson learned is, when you search remote areas many floors above a high-rise fire and encounter smoke, wear your mask! Don`t think that just because there is no heat in the smoke, you are far above the fire, or the fire has been extinguished that the smoke is not dangerous–it can be deadly!
The heated, sealed environment in a high-rise fire is a major problem for firefighters. Protective gear and SCBA mask weigh 50 pounds, which adds to the heat stress on the body. Even in areas remote from the fire, when the air-conditioning is shut off, the temperature in the building will rise to as much as 100ºF in as little as one hour, placing added stress on firefighters.
As one firefighter observed, at a low-rise residence building fire, if after 20 or 30 minutes of fast and furious interior firefighting action you don`t extinguish the fire, you can back outside and set up an outside stream. At a high-rise fire, on the other hand, you spend the next two or three hours still inside trying to extinguish the fire, and it is hot. Your gear protects you from smoke and flame, but there is no protection against the buildup of body heat. In fact, the gear adds to the heat by preventing evaporation of body heat.
All personnel must be aware of the danger of heat exhaustion and take necessary action during a high-rise fire. Chiefs must be aware of the limits of exposure time. Extra firefighters must be available for relief and replacement. Company officers should rotate firefighters for maximum effectiveness and order rehab when necessary. Firefighters have the responsibility to not work so hard that they are exhausted and need medical attention–they must pace themselves and ask for rehab when needed. It takes two firefighters to assist and administer first aid to a firefighter who collapses into unconsciousness from heat exhaustion.
For firefighters advancing attack hoselines at a high-rise fire, after you use up a 45-minute air bottle, replace it and take a rest. Then return to your task, if possible. Firefighters manning handlines should not have to use more than one or two bottles before being sent back to quarters.
Every floor in a high-rise building contains a plenum–a large space created by a suspended ceiling. This space above the suspended ceiling and below the underside of the floor above is used as part of the return air system of a central air-conditioning system. Miles of wire covered with polyvinylchloride insulation is placed up in the plenum. A fire extending into the plenum will ignite combustible insulation and spread throughout the large concealed space. To prevent firefighters from being trapped by fire spreading above their heads while they advance hoselines or search, they must periodically lift up a ceiling panel out of its frame with a pike pole to check for spreading flame or smoke.
Large shaftways such as elevator shafts, package and mail chutes, conveyor belt openings, smoke shafts, garbage chutes, and utility wire and plumbing shafts are found in high-rises. Normally such shafts, which extend 20 or 30 stories, are enclosed with safeguards such as railings, gypsum block walls, self-closing doors, and trap doors to prevent occupants from falling into them. However, during a fire these safeguards are destroyed, rendered inoperative, or opened by firefighters. In a dark or smoke-filled environment, firefighters can fall to their deaths in these shafts. Two Chicago firefighters fell to their deaths in an elevator shaft. In New York City, the aluminum railing around a smoke shaft melted. A firefighter moving from the stair enclosure into the occupancy almost fell into the smoke shaft and down 20 floors. The lesson learned is, don`t expect the usual safeguards in a high-rise building to be in place during a fire. Don`t move blindly in smoke or darkness–get down on your hands and knees and crawl to safety, feeling the floor in front of you. n
VINCENT DUNN, a 38-year veteran of the City of New York (NY) Fire Department, is a deputy chief and previously served as division commander for midtown Manhattan. He developed the National Fire Academy “Command and Control of Fire Department Major Operation” course and wrote the collapse rescue procedure used by New York City fire rescue companies. He is a lecturer; is the author of the text and video series Collapse of Burning Buildings and the text Safety and Survival on the Fireground, published by Fire Engineering Books and Videos; and has had numerous articles related to firefighter safety published in fire service magazines. He 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 is a member of the New York City Fire Chiefs Association, the NFPA, and the IAFF. He can be reached at (800) 231-3388.