Using Building Systems To Fight High-Rise Fires

One of the first lessons an incident commander learns at a high-rise fire is that success or failure depends on the building’s systems. If these systems operate successfully, you will be successful. If the systems fail, your firefighting will fail and you will not extinguish the fire quickly.

When firefighters respond to a fire in a low-rise building, they bring with them all the systems they need to fight the fire – their feet are the “vertical transportation system” that gets them to the upper floor, the hoseline they stretch is their “water-supply system”; and the fire department radios strapped over their shoulders are their “communications system.” The fire department “systems” used in low-rise firefighting almost always work successfully.

It is different when firefighters respond to a fire in a high-rise building. There, firefighters are totally dependent on the building’s systems for firefighting, and they are not always dependable.

 

Four systems in place

There are four systems in a high-rise building that firefighters depend on during a fire:

1. The vertical transportation system (elevators) that take firefighters and equipment up to the fire floor.

2. The water supply pipe system for standpipes and sprinklers.

3. The communications system that will allow or prevent firefighting radios from transmitting through concrete and steel.

4. The fire-resistive system of walls, floors and ceilings that are designed to contain a fire to one floor.

A chief officer or company officer who has spent years fighting fires in low-rise buildings and is transferred to a downtown high-rise district must learn how high-rise building systems can assist or hinder strategy:

1. Elevators. Unfortunately, at some high-rise fires, the vertical transportation system (elevators) can fail. Fire, heat or water can cause electrical malfunctions in elevators in phase-one (normal) use or phase-two (firefighter) use. If flame or heat distorts a call button or wires in an elevator shaft become wet, the elevator may malfunction.

There have been instances when elevators in phase two took firefighters up to the fire floor instead of where the officer sent the car, which was two or more levels below the fire. At some fires, runoff water from hose streams or sprinklers flowed into hallways and entered elevator shaftways, causing elevators to stall and trap firefighters inside the stuck cars.

In some situations, on the fire department’s arrival in a high-rise building lobby, some elevator cars will not recall to the lobby when the phase-one recall system is used. These elevators must be searched for trapped victims and used by firefighters to access upper floors. At other times, when a firefighter leaves other firefighters two floors below a fire and presses the button to return to the lobby for reinforcements, the elevator car instead goes above the fire floor, endangering the firefighter running the elevator.

 

Alternate strategy

In New York City, an eight-year study of 179 major fires revealed that elevators failed at 59, or one third, of the fires. If elevators fail at a high-rise fire, an alternate strategy is to have firefighters carry tools and equipment up the stairs. This “stairway support” requires a large commitment of personnel and delays the first line extinguishing the fire.

The importance of having serviceable elevators at high-rise fires was demonstrated in a study conducted by the National Institute of Standards and Technology (NIST) and the International Association of Fire Fighters (IAFF). During a test fire on the 10th floor, firefighters using elevators to transport tools, air bottles and equipment from the lobby to the staging floor reached their destination 10 minutes faster than when firefighters carried the items up the stairs using “stairway support” or “ground support,” as described in National Fire Protection Association (NFPA) 1561, Standard on Emergency Services Incident Management System.

Stretching or carrying hose, masks and tools up the stairs to a high-rise fire requires at least one extra firefighter per floor. To carry tools and hose from a lobby to the 10th floor would require at least 10 additional firefighters to act as stairway support and replace a broken elevator system. An incident commander must transmit additional alarms to bring more resources when an elevator fails at a high-rise fire.

2. Standpipe and sprinkler systems. Records show that sprinkler systems successfully control fire in 93% percent of incidents. However, sprinkler systems are designed to control a fire, not extinguish it. Firefighters are needed to extinguish the blaze after the sprinklers control it, to search for trapped or injured victims and to shut off the sprinkler system after the fire is extinguish and return it to service. At night, when commercial buildings usually are closed, firefighters must replace sprinkler heads and put the system back in service before leaving the scene.

The NFPA estimates that sprinkler systems fail at 7% of structure fires (one of every 14 fires), primarily due to human error. According to the NFPA, two-thirds (65%) of sprinkler failures were because the system had been shut off before the fire. Another one-sixth (16%) of failures occurred because manual intervention defeated the system, for example, by shutting off the sprinklers prematurely. Lack of maintenance accounted for 11% of failures and 5% occurred because the wrong type of system was present. Even though automatic sprinklers have stored water supplies or connections to water mains, an incident commander must always order a hoseline stretched to augment the supply of water to a sprinkler system.

A high-rise building may or may not have a sprinkler system, but it must have a standpipe system. Firefighting in a high-rise building depends on the standpipe system getting water to upper floors. Instead of stretching 10 or 12 lengths of hose up the stairs, three or four rolled or folded hose lengths are taken up by firefighters in an elevator and connected to the standpipe outlet on the floor below the fire.

A high-rise standpipe system also can fail due to human error or poor design. In 1988, for example, a fire in the First Interstate Tower in Los Angeles, CA, destroyed five floors of the building and killed a maintenance worker when the elevator he was riding in opened on the burning 12th floor. The standpipe system in that building was shut down for repairs at the time of the fire – human error. There was insufficient water pressure for the first 40 minutes of the fire because the standpipe system’s fire pumps were not operating. A design defect in that building was the installation of standpipe aluminum outlet valves inside the occupancies. Flames melted the aluminum valves, letting water drain from the standpipe system.

 

When standpipe systems fail

When a standpipe system fails, firefighters will notify the incident commander by radio there is low pressure or not water in the system. An incident commander must consider several alternative strategies when notified of standpipe system failure.

The most common problem is low water pressure. When low water pressure is reported to the incident commander, the first strategy is to order pump operators to increase engine water pressure. A rule of thumb for standpipe engine pressure is 50 psi for a smooth-bore nozzle, plus 10 psi friction loss for four lengths of hose off the standpipe outlet; plus a half-pound of pressure for each floor above ground level to compensate for “head pressure” necessary to overcome water weight in the pipe, plus an extra 25-pound pressure for friction loss in the standpipe and supply lines to the inlet. Another strategy is to order firefighters to remove any pressure-regulating valve from the outlet that may be restricting water. If the standpipe has a pumping system in the basement, the incident commander can send a firefighter to the basement with an engineer to start and increase water pressure delivered by the pumps. Last, but not least, check the hose for kinks.

3. Communications systems. A communications system, or lack of one, determines whether the incident commander can command and control a high-rise fire. Communications between incident commanders and firefighters are critical at high-rise operations. There can be no command, control or coordination at a high-rise fire without communications.

Incident commanders at a command post must receive progress reports, requests for more resources, Mayday signals and reports of the discovery of injured victims from fire officers on upper floors. In turn, officers operating on upper floors must receive orders from incident commanders at a command post. The bad news about communication systems is that concrete and structural steel framework of a high-rise building interferes with fire department radios. The good news is that some high-rise buildings are installing communications antenna systems to enhance transmissions from firefighter radios.

Before a certificate of occupancy is issued for a new high-rise building, fire department radios should be tested inside. These radios must be able to transmit messages from a command post in the lobby to the roof and from the lobby to the lowest cellar level. If fire department radios do not transmit to and from these locations in the building because of interference, an antenna must be provided to assist fire department radios.

 

Backup resources

Many fire departments have hard-wire communications systems with 300 or more feet of wire for backup at a high-rise fire if radios fail. These communications require firefighters to stretch the wire up a stair, so stairway support resources are required. All the alternative communications systems are less effective than the fire department radio system because they allow only limited communications. An antenna system that enhances fire department radios at a high-rise fire and allows radio communications between incident commanders and all officers and firefighters at the scene is the best.

4. Fire-resistive systems. In the 1890s, when the first high-rise structure was built above the height of the fire department’s tallest ladder, the builder told the fire chief that the building construction was fire resistive and fire would not spread from one floor to the floor above. Unfortunately, the fire chief agreed. Under the “passive-fire-resistive” concept, construction alone would prevent fire spread from floor to floor. The public and the fire service now know this is not true, and we have active fire resistance to stop fire in high-rise buildings: firefighters’ hose streams and automatic sprinklers.

 

Spreading fire

Fifty years ago, the National Fire Protection Handbook, 10th edition, defined “fire resistive” as “a building which would confine fire to one floor, barring an explosion or collapse.” Experience shows that this definition does not apply to modern high-rise buildings. There is no such thing as a fire-resistive building. Fire will spread from floor to floor in a non-sprinklered high-rise building if it is not extinguished by firefighters. Fire and smoke can spread in a fire-resistive building by auto-exposure (from a window to a window above), by ducts of a central air system the connects several floors, by spaces around the perimeter of a building between the edge of a floor slab and the inside of a curtain wall, by poke-through holes in utility closet floors and through cracks in concrete floor slabs.

This was demonstrated at World Trade Center Building 7 on 9/11. When firefighters did not attempt to extinguish the fire due to the collapse danger, the fire spread from floor to floor and the building suffered a global (total) collapse in seven hours. After 9/11, NIST redefined fire-resistive construction to mean “construction that will burn and not collapse,” with no mention of containing fire. This new “dumbed-down” concept of fire resistance is a warning sign to firefighters and incident commanders that fire will spread from floor to floor in a high-rise building if we do not extinguish it and, like Building 7, the burning structure may collapse. A high-rise building must have active fire resistance, which means fully automatic sprinklers to control a fire and a fire department to fully extinguish any fire and rescue trapped and injured victims.

 

A classic system failure

A classic building system failure occurred in 1990, when the One Meridian Plaza high-rise office building in Philadelphia burned and killed three firefighters trapped on the floors above. In addition to the tragic deaths of the firefighters, all of the building systems failed. The building was destroyed by fire spreading from floor to floor. It was declared a collapse danger during the fire and the incident commander withdrew all firefighters and let the building burn. After the fire, the building was declared structurally unsound and had to be demolished. This was the most significant high-rise fire of the 20th century and must be studied by fire departments for research, analysis and pre-planning high-rise fire strategy.

The progressive building system failures started with the standpipe system. The pressure-regulating valves were set improperly and restricted water pressure to the hose streams. The valves were fixed permanently to the pipe and could not be removed by firefighters. Special tools needed to adjust the pressure were not on the premises. As a result, a relatively small fire spread throughout the large floor area and then up nine floors of the building.

Next, the elevator system failed, forcing firefighters to walk up 20 flights of stairs with tools, hose and masks. To compensate for the failure of the ineffective standpipe system, firefighters stretched a large-diameter hose up those 20 flights. At the same time, firefighter communications failed because of concrete and steel in the building. To compensate, firefighters set up a radio-relay system to communicate from the lobby to upper floors. Also at that time; the electric power system failed and the building was in compete darkness, so firefighters set up portable lighting on upper floors. Finally, the fire-resistive system failed and fire consumed the building floor by floor.

During a nine-hour firefighting operation, fire officers discovered and reported expanding cracks in fire stair walls. A structural engineer was called to the scene and he told the incident commander that the building could collapse. The incident commander ordered firefighters to set up outside streams from across the street in adjoining high-rise buildings. All firefighters were ordered to withdraw from the building and let it burn.

One of the most unbelievable system failures in that building took place not during the fire, but during its design and construction. A post-fire investigation revealed that sprinklers were installed only in below-grade areas and the top nine floors. Sprinklers were omitted throughout the middle 29 floors. This let flames spread nine floors, from the 22nd to the 30th floor. When flames reached the 30th floor, the first upper floor with automatic sprinklers, nine sprinkler heads activated and extinguished the fire, but it was too late. Fire destroyed 25% of the structure.

The lesson learned at this fire was the importance of high-rise building systems. If the systems fail, the firefighting fails. In addition to the failed systems and poor fire protection design, this fire is a landmark because it marked the first time in the history of the American fire service when an incident commander withdrew all firefighters from a structural-steel-frame, high-rise building because of collapse danger. The incident commander withdrew all firefighters from the burning building, but kept water supply hoselines feeding the sprinkler system. Water fed the nine sprinkler heads that finally extinguished the fire. Ten years later, after millions of dollars were spent on litigation, the burned-out, vacant high-rise building was deemed structurally unsound and ordered demolished. n

 

REFERENCES

Final Report on the Collapse of World Trade Center Building 7. National Institute of Standards and Technology. November 2008.

High-Rise Office Building Fire One Meridian Plaza. U.S. Fire Administration/Technical Report Series. USFA-TR-049. February 1991.

McKinsey Report: Increasing FDNY’s Preparedness. FDNY Fire Operations Response on September 11. FDNY/McKinsey & Co. August 2002.

NFPA 1561: Standard on Emergency Services Incident Management System. National Fire Protection Association. 2008 edition.

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