NFPA Journal®, March/April 2005
by Jaime A. Moncada, P.E.
|The fire reaches the 47th floor of the Parque Central in Caracas, Venezuela. See larger image.|
|One of the last attempts by the government helicopters to cool down the fire using water-filled buckets. See larger image.|
This image was taken by retreating fire personnel as they left the partially collapsed 35th floor. See larger image.
Photos: Courtesy of Jaime Moncada
Despite the fact that a sprinkler system had been installed in the Parque Central the fire did more than U.S. $250 million in damage, burning the structure’s contents from the 34th floor to the 50th. Why? Because, as previous inspections revealed, the sprinkler system had not been properly tested or maintained, thus it wasn’t in a working condition; the building designers said local fire alarm panels weren’t connected to a building-wide panel; and the standpipe system was inoperable at the time of the fire.
Collecting credible first-hand information about major fires in
Although NFPA was not officially invited to investigate the Parque Central fire, I visited the scene the day after the fire to interview
The twin towers of the building were completed in 1982 as part of a 25-acre (10-hectare) complex known as Parque Central, which was built between 1970 and 1982. The complex also contains more than 1,100 retail stores, seven 40-story residential towers, and a 35-story hotel. The
The reinforced concrete structure consists of perimeter columns connected by post-tensioned concrete “macroslabs” that are each 10 feet (3 meters) deep and above the second–floor mezzanine, the 14th, 26th, 38th, and 49th floors. There’s no central core.
Individual floors between the macroslabs have a steel-deck floor supported by steel beams, all protected underneath with spray-on Cafco Blaze Shield DC/F mineral glass fiber wool with cement fireproofing. According to Cafco’s Manny Herrera, the floor was designed to meet
Five structural bays rest on four lines of columns in each direction supporting the steel deck. In effect, the concrete structure includes five stacked steel buildings, each supported by a macroslab. During the fire, two steel decks partially collapsed; other than that, there was no collapse inside the building. However, deflection in some steel beams was severe.
Fire protection and life safety
The original designers took extraordinary care to design a building that included state-of-the-art high-rise fire safety for the 1970s. The building had fire detection and alarm systems, fire hose cabinets, and pressurized stairs. A wet-pipe sprinkler system, utilizing copper tube and designed following the pipe-schedule method, was installed and connected to on-off sprinklers. The on-off sprinklers were Grinnell’s Aquamatic, Model F920B, with a temperature rating of 165°F (74°C), manufactured in 1981. The UL-listed, FM-approved F920B is designed to reset itself after operation by way of an internally mounted pilot valve with a heat-responsive bi-metallic snap disk and a piston assembly.
According to maintenance personnel, the sprinklers leaked soon after the building was put into service, and, instead of replacing the sprinklers, valves were added over the years to “manage” the leaks. All the control valves I saw in the
The installation protocol for this sprinkler is atypical. Before installation, the installer must take a series of steps that include flushing the piping and precharging the sprinklers using a manifold connected to a pressure source of at least the system pressure or 10 psi (0.7 bar). After precharging, each sprinkler must be operated by applying minimum heat with a propane torch to the sprinkler snap disk until the sprinkler opens. After this procedure, the sprinkler can be removed from the manifold and installed on the sprinkler system.
According to Grinnell, failure to precharge may result in water discharge from sprinklers until pressure at the sprinkler reaches about 10 psi (0.7 bar).
The sprinkler leakage soon after the building was put into service coincides with problems the building experienced with its water supply system. Originally, the system was to be supplied by a large-capacity elevated tank on a hill not far from the site. The head or gravity pressure from this tank was reportedly sufficient to pressurize the system up to the 25th floor through an 8-inch (203-millimeter) standpipe, and booster pumps were installed on the 26th floor to pressurize the system in the remainder of the building.
However, the elevated tank failed soon after the building was opened and was replaced by a connection to a high-pressure municipal water main and later to water pumps that were not listed for fire pump service. A plausible explanation for the sprinkler issue is that the precharging protocol was never adhered to and, with the water supply problem, system pressures fell below 10 psi (0.7 bar) throughout, allowing some sprinklers to leak.
Each office floor also had an independent fire alarm panel connected to smoke detectors and horns. The original design called for these independent panels to be interconnected to a building-wide panel, but according to the building designers, that project was never funded. The local panels I saw on the
Means of egress from the towers consisted of two enclosed stairwells 50 inches (1.27 meters) wide that reportedly were pressurized. Egress capacity and travel distance were well within the requirements of NFPA 101®, Life Safety Code® , requirements.
The first report of the fire came at 12:05 a.m. on Sunday from a neighbor who called the CFD dispatcher. The first responding unit from a fire station within the Parque Central complex arrived at the base of the building a few minutes later and was directed to the fire floor in the
On the fire floor, the first responders found a developing fire and connected their hose lines to the building standpipe system. When they discovered that the standpipe system wasn’t working, the fire chief ordered a 9,250-gallon (35,000-liter) cistern connected to a fire engine with a 1,200 gallon-per-minute (4,500-liter-per-minute) pump to pressurize the standpipe using the building’s fire department connection. However, they were unable to pump any water into it. According to fire department personnel, a lack of maintenance made the standpipe inoperable.
Commanders at the scene decided to bring a 2-inch (63-millimeter) hose line, fed by fire engines at the ground level, all the way up one of the fire stairs. Two portable booster pumps, each flowing 264 gallons per minute (gpm) at 58 psi (1,000 liters per minute [lpm] at 4 bar), were used to provide adequate pressure above the fire floor.
At approximately 1:15 a.m., firefighters working with two 1-inch (38-millimeter) hose lines from different locations above the 34th floor were able to slow the upward movement of the fire considerably. By 3 a.m., a second 2-inch (63-millimeter) hose line, identical to the first one, had been put into service, and firefighters confined the fire to three to four floors above the 34th floor. This approach was successful through the first five or six hours of the fire, when the fire spread vertically at a rate of approximately one floor every three hours. The 27th floor became the main staging area for about 100 firefighters.
At 7 a.m., some of the booster pumps started to malfunction, and the fire regained intensity, spreading vertically at a rate of about one floor per hour until approximately 10 a.m. Around 11 a.m., the fire breeched the fifth macroslab, below the 39th floor, and around noon, the stairwells’ fire enclosure started to fail. Concerned that the building might collapse, the fire chief immediately ordered that interior firefighting operations be abandoned. It should be noted that the CFD only reported minor injuries among its personnel during this risky operation.
The fire continued to move upwards through the afternoon, at a rate of about 2 1/2 floors per hour. Between 2 and 3 p.m., the Venezuelan government began using helicopters with water buckets, commonly used on forest fires, in an unsuccessful attempt to slow the fire down.
The fire eventually burned itself out at 3 a.m. on Monday morning, after spreading and consuming the contents of some 17 floors, more than 24 hours after it began.
Past history and performance shows that this fire could probably have been controlled quickly by a standard wet-pipe sprinkler system and that the fire department’s chances of controlling the fire at, or a few floors above, the floor of fire origin would have increased if the standpipe system had been working. This fire highlights the importance of periodic inspection, testing, and maintenance of fire protection systems, as well as the importance of strictly following manufacturers’ installation instructions.
This incident once again reminds us of the fire safety challenges high-rise buildings present and demonstrates that no fire department, no matter how large, professional, and well-equipped, can effectively control a fire without properly designed passive and functioning active fire protection systems. The CFD performed admirably in an impossible task, and its commanders made difficult decisions that ultimately proved to be the correct ones.
I wish to thank CFD fire chief Colonel Rodolfo Briceño for his assistance, as well as the many men and women of the CFD who provided information and support during my visit. Comandante Briceño retired on November 24, 2004, after 40 years of service with the CFD.
Jaime A. Moncada, PE is a fire protection engineer based in
In this Section:
Fire spreads in South America’s tallest high-rise building in
|NFPA’s contribution to Latin American fire safety