Fire Protection Engineers Meet, Express Concerns for Life Safety
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Four recent hotel fires in Las Vegas were worthy of special note, the speaker was saying. The audience was full of fire protection professionals, and it was understandable that their thoughts would jump to the tragic and wellknown fires at the MGM Grand and Las Vegas Hilton.
But it was not to those fires the speaker referred. Three of the fires did occur at the MGM Grand, he said, but they were after the fatal fire and after certain changes. One was the night before the fatal fire, but across the street at the Barbary Coast.
The public never heard about them, the speaker explained. What made them noteworthy was that all four were handled without fanfare by automatic sprinkler systems.
The speaker was Russell P. Fleming, vice president of engineering at the National Automatic Sprinkler and Fire Control Association. The occasion was the 10th annual seminar of the New York Metropolitan and New Jersey chapters of the Society of Fire Protection Engineers, held March 25.
“Sprinkler systems are already installed in hundreds of thousands of buildings,” Fleming said, “and yet there has never been a multiple loss of life from fire in a building fully protected by sprinklers.
Despite well-publicized fires, like the one at the MGM Grand, in buildings without complete sprinkler systems, many building designers and owners still make a risky decision favoring shortterm economics over life safety. But Fleming believes that more of them are now returning to the simple solution of sprinklers.
Australian experience
System reliability was never the problem. Fleming described a study of 82 years’ experience of sprinklers in Australia. Those statistics are considered especially accurate because in Australia every sprinkler actuation must be reported by law. The success rate of sprinklers in controlling fires: 99.8 percent.
For the future, Fleming sees a spreading use of fast-response sprinkler heads. He credited their evolution to efforts of a U. S. Fire Administration project focusing on residential protection. Wider acceptance has been slowed by NFPA Standard 13D, however, which limits use of the new heads to one and two-family homes and mobile homes. But Fleming expects that limitation to be opened up.
“In recent years—and especially in the past several months—there has been a growing concern over the role of smoke control as part of a structure’s fire protection program,” said Carl F. Baldassarra of Schirmer Engineering Corp.
He described five principles used in smoke control. Control of fuel types and amount is one, but this isn’t feasible in mercantile and most business occupancies. Best of all is limiting the size of a fire with sprinkler protection. If a fire develops, smoke can be contained within a zone by surrounding higher pressures. Smoke can also be diluted by fresh air or exhausted directly to the outside.
For unsprinklered buildings, there are three common methods of smoke control not depending heavily on the operation of machinery: unit vents, smoke shafts and exterior panels. But Baldassarra said present code criteria for unit vents is largely outdated, smoke shafts are not considered reliable because the gravity action can be upset by broken windows, and opening exterior panels is dependent on manual action usually after the fire department arrives.
“One of the simplest methods of smoke control in buildings equipped with mechanical air handling systems,” said Baldassarra, “is the automatic shutdown of the affected heating, ventilating and air-conditioning unit by means of a duct-mounted smoke detector.”
Some engineers design the HVAC unit to shut down when a sprinkler opens. Both methods were said to be relatively inexpensive, but many codes do not recognize them as smoke control.
Performance-oriented
Baldassarra suggested that codes should be performance-oriented rather than prescriptive. This would better allow, he said, “the use of various schemes which have proven adequate and cost-effective in the past.”
A prescriptive code would specify, for example, a system capable of producing six air changes per hour computed on a volume of 12 feet above each pedestrian level. A performance-oriented code may just require the system to restrict movement of smoke to the general area of fire origin and to maintain the means of egress in a usable condition.
When codes require too-complex smoke control systems, according to Baldassarra, reliability and cost-effectiveness suffer.
He told of a large, enclosed, fully sprinklered shopping mall that was also required to have a complex prescriptive smoke control system. He said engineers would have designed a simpler system more compatible with the sprinkler system. Instead, because of resulting reliability problems, “complete periodic retests are also necessary to assure continued proper operation of the system. The retests represent substantial recurring costs.”
Concluded Baldassarra: “The fact that a high degree of life safety is provided by the automatic sprinkler system … suggests little or no benefit from this sophisticated smoke control system intended to provide an added degree of safety.”
BOCA
Building codes ordinarily are not the leading edge of building practices, according to Ken Schoonover, manager of technical services at Building Officials and Code Administrators (BOCA) International. Rather, codes follow the state of the art until fire protection engineers jespond to effects, he said.
BOCA’s function is to develop coordinated model codes for adoption in localities, although most big cities write their own codes.
In any event, building codes are not the ultimate design tool for life safety, Schoonover said. For example, the builder has to recognize his pivotal role—especially when he doesn’t follow the design plan. And a building code is only a minimum set of regulations, not a guide to perfection.
The BOCA code is a consensus code. It is not written in some ivory tower, Schoonover reminded, but evolves with input from any person or group affected.
Flammability of furnishings
Joseph Kiementowicz is a fire protection engineer at the Port Authority of New York and New Jersey, which manages the area seaport, bridge and airport facilities. He described an active fire research program conducted by the Port Authority.
The public may think of an airline terminal building as a place where no real fire hazard can exist. After all, the main combustibles—chairs—occupy only 10 to 15 percent of the floor area in a noncombustible building, right? But a new terminal at Kennedy Airport sustained a $2.5-million fire, prompting Port Authority officials to ask, “Are we building crematoriums for the public?”
So the Port Authority began studying the flammability of furnishings by necessity. One of the things discovered was that the standard time-temperature relationship curve reflected furnishings of the old days (1920s). New materials gave off many more BTUs per pound when burned.
The critical beginning
“Our biggest hope,” Kiementowicz said, “is to show what happens in the beginning of a fire in contemporary materials, and how little time we have to make critical actions.”
He then showed the results of one test on common furnishings. A temperature of 2000 degrees at the carpet level was reached in less than three minutes.
Kiementowicz also showed how some manufacturers have been misguided. It seems cotton batting had been replaced by polyurethane in some chairs because polyurethane resists a smoldering fire better. The problem, as he demonstrated, was that the fire spread properties of polyurethane were potentially disastrous.
That situation came to a head when 80 plushy and comfortable polyurethane chairs were scheduled to be installed in an airport lounge. Simple, everyday chairs, they were called. In his test, however, Kiementowicz was shocked to see flashover occur even without a confining ceiling to hold heating gases coming off the burning chair.
The chairs were never installed. Said Kiementowicz: “There was enough fuel in those chairs to blast off the space shuttle.”
Day to day
It’s a day-to-day battle. John T. O’Hagan, former New York Fire Commissioner and now a fire safety consultant, followed with his observations on risk analysis.
“Architects and buildings seem intent,” O’Hagan said, “on ignoring the lessons of the past by providing structures that can be detrimental to life and property.”
Six significant high-rise fires were used for analyses of construction types. Most have been covered in the pages of Fire Engineering or in O’Hagan’s book, “High-Rise/Fire and Life Safety,” published by Fire Engineering. In each case, potential flaws had been built in.
“From the exterior, we cannot appraise the risk. But if we took the time to investigate and understand the risk of collapse inherent in a particular assembly, we could probably reduce the loss of life among fire fighters by 20 percent and increase the effectiveness of fire control operations,” O’Hagan said.
