FIRE LOSS MANAGEMENT

FIRE LOSS MANAGEMENT

FIRE PROTECTION

SFPE

Part 11: EXTENSION-FLAME SPREAD

THE LEAST UNDERSTOOD of the elements that contribute to the spread of fire in buildings is interior finish. It is generally known that a combustible building can burn down, and most people will agree that combustible contents can turn a fire-resistant building into a roaring oven, but the interior finish problem eludes all but the most knowledgeable. Perhaps it is a response to the myth that “clean places seldom burn.” Further, it is hard to believe, but you can “remodel” and “modernize” a 70-year-old building and in the process make the fire loss hazard infinitely worse.

Fatalities have occurred in training operations in which abandoned buildings were burned because the hazard of high flame spread finish was not recognized. Fatalities and injuries have occurred in firefighting because high flame spread material was involved.

Do you know offhand what the following have in common: asphalt-protected metal; burlap; canvas; cardboard; fiberboard tiles and sheets; relatively noncombustible insulation with a paper vapor seal; paperboard pressed in sheets, tiles, and planks; plastic tile and corrugated sheets; and plywood and various veneers? If you do, you know more about them than many of your contemporaries. These are typical building materials with high flame spread characteristics.

Such materials figure in many, if not most, of the serious fires in which large losses of life have occurred: the Coconut Grove Nightclub, Boston, 1942 — 492 dead; the Ringling Brothers Circus, 1944—168 dead; the La Salle Hotel fire, Chicago, 1946—61 dead; St. Anthony’s Hospital, Effingham, Illinois, 1949 — 74 dead; and Dale’s Penthouse Restaurant, Montgomery, Alabama, 1967—25 dead. In addition, a huge property loss from a computer fire in the Pentagon was attributed directly to the presence of combustible acoustical tile.

Hie flame spread or fire growth problem is not limited to building materials—it has become a significant contents factor. Thus the fire growth characteristics of both contents and the building itself must be taken into account when preplanning. For instance, many fire departments rely solely on small hose for high-rise packs and arc not prepared in mindset or training to operate big lines, even multiversal nozzles, in fire-resistive high-rise buildings.

I will discuss contents in more detail in the next issue. Note, however, that in 1975 in a “Hazard Alert” the Society of Fire Protection Engineers warned, “The rate of fire development can create a condition that may tax or overpower traditional fire defenses. Defenses of the past, both passive and active (evacuation, alarm, ventilation, and manual fire control), have not been designed by engineer or code to anticipate this hazard. This is primarily a furnishings problem. Many occupancies (residences, office buildings, theaters, and hospitals) are being affected.”

INTERIOR FINISH MATERIALS

The characteristics of interior finish materials that are relevant to fire problems are ability to spread fire (flame spread characteristics), contribution of fuel to the fire, and quantity of smoke generated. If we in the United States were really serious about reducing our disgraceful national fire loss, we would ban materials that have high flame spread characteristics, that contribute substantial fuel to the fire, or that produce large quantities of smoke. Unfortunately our commitment to reducing the fire loss is too often limited to handing out pamphlets.

Fires involving contents and interior finish may burn slowly for some time. Gases are being generated in increasing volume and temperature. Suddenly all the combustible surfaces burst into flame—flashover. The time that it takes to reach flashover is a critical measure of the fire safety of a room, corridor, or building. When combustible finishes are involved, this time period is only a few minutes.

The method of applying an interior finish may vitally affect the fire safety. A relatively slow-burning linoleum was applied to a wall as a wainscot with a highly flammable adhesive. The fire raced down the corridor behind the cover faster than people could run. A noncombustible mineral wool insulation with exposed asphalt-impregnated vapor seal presents an extraordinary flame spread hazard.

It is extremely difficult to determine the fire characteristics of a building material through visual inspection. An actual test of the material in place may result in disaster. The application of a match to a small sample is simply not an adequate test, and reliance on some vague source such as “building authorities,” “government,” “insurance underwriters,” or even “the reputation of the manufacturer” is fraught with peril.

In the post-World War II period, fire protection experts including myself were concerned about losses of fire in buildings lined with the newly popular combustible fiberboard. The phenomenon became known as flame spread. The industry was outraged. At any meeting held to discuss the subject you could count on a representative of the trade association or a manufacturer to claim, “The fiberboard is safe. It is coated with a cornstarch coating that withstood the industry-sponsored test of a half thimbleful of alcohol, so what is all the fuss?”

Early acoustical treatments did not take flame spread into consideration. It is difficult if not impossible to get information on installed acoustical treatment as seen in this auditorium.

(Photos by Francis L Brannigan.)

This low-density, combustible fiberboard ceiling is burning furiously on the visible surface, on the back side, and within the fibers.After being washed with a 2 1/2-inch line the fire still persisted. Codes permit a new ceiling with a better flame-spread rating to be installed below a combustible tile ceiling. Fire can still spread undetected above the newer ceiling.The exposed vapor seal will spread fire throughout this hardware store ceiling in seconds. Flaming particles of paper can drop, igniting combustibles below.

Suddenly the industry made an about face, supporting testing, standards, and regulation. Did our arguments convince them of the hazards? Not exactly.

In Effingham, Illinois, St. Anthony’s Hospital had been lined with sound conditioning tiles made of combustible fiberboard. Someone told the nuns who owned the hospital that the tiles were hazardous. They wrote the manufacturer, who assured them that the tiles were safe and had passed a government-approved test (under its standardization program, the government assigned a number to an industry-approved standard with no independent testing). On April 4, 1949, the hospital burned. Seventy-four lives were lost, mostly babies in the nursery and nuns and nurses who would not leave them behind.

The hospital sued the manufacturer. There was a massive sealed settlement (the sealing of settlements in liability cases is a legal device that is designed to keep the information about why the disaster occurred from the public; thus it is liable to happen again). Of course the facts became common knowledge in the industry. Boards of directors of producing companies were astonished to learn the extent of potential liability because of the acres of fiberboard they put in place. They quickly directed their companies to cooperate in developing standards for flame spread. The result is that it is just about impossible to purchase commercial ceiling tiles today that do not carry the flame spread rating on the box.

MEASURING FLAME SPREAD

Interior surface materials are tested in ASTM E-84, the Steiner Tunnel Test, to determine their flame spread rating. In this test a sample of the material is affixed to the underside of a removable top panel of a tunnel. It is installed in the same manner as in actual building use—for example, glued, stapled, etc. A gas flame is ignited at one end. A constant draft is provided so that the flame spread can be observed and rated on a scale that places cement asbestos board at 0 and red oak at 100. The density of the smoke is measured by a photoelectric cell. The amount of fuel contributed by the sample over and above that of the gas flame is measured by the increase in temperature. The numerical value assigned to a material represents the degree to which fire spreads over the material at a greater or less speed than over red oak. For instance, a flame spread rating of 50 means the flame spread over the tested material at half the speed it did on red oak. A flame spread rating of 200 means the flame spread over the test material twice as fast as it did over red oak.

NFPA 101: Life Safety Code Handbook classifies materials by flame spread ratings as follows: Class A flame spread 0-25, Class B flame spread 26-75, and Class C flame spread 76-200. (For a discussion of the ASTM E-84 test, see chapter 7 of my book Building Construction for the Fire Service. For a most detailed discussion, see the NFPA Fire Protection Handbook, 16 Ed., pages 7279.)

A deadly hazard to firefighters is created when a building containing combustible tile is remodeled. The code probably requires that the new ceiling meet the flame spread requirements listed above. In no case known is there a requirement that the old tile located above the new ceiling be removed. This provides a deadly source of fuel for fire to burst out on unsuspecting firefighters, which did happen in Wyoming, Michigan, killing two firefighters. Even there the code was unchanged.

Point out the hazard to the owners and tenants. Let them know how you will have to tear the ceiling apart and use heavy streams to knock out this deadly threat. Document everything; it may come in handy in case a lawsuit ensues.

ASTM E-84, the Steiner Tunnel Test, is the usual basis for legal regulation of flame spread. Should it be desirable to prosecute a person criminally for installing material that did not meet flame spread requirements, it might be necessary to test a sample. The sample required is about 22 feet wide and 24 feet long. It may be difficult to get a sample this size, but it may be necessary if a prosecution is to be successful. The sample should be complete as installed. The feet that the method of attachment is very important to the actual flame spread of combustible tiles was discovered when a full-size sample of tiles glued to gypsum board showed a much greater flame spread than the same tiles removed from the board for shipping purposes.

ASTM E-162, the radiant panel test, requires a sample only 6 by 18 inches. Samples this size are easier to obtain. Results from this test can be correlated in a general way with ASTM E-84. The information gathered can be very useful in developing better code requirements, but if the question of discrepancy in the installed material is going to be criminally significant, the prosecutor should be made aware of the difference in these tests. It might be critical to the case that the test be performed under the same conditions as the code requires, which would almost invariably call for using ASTM E-84.

BUILDING COMPONENTS

The flame spread problem is not limited specifically to surface treatments such as acoustical tile. Some building components themselves can provide significant flame spread.

Combustible metal deck roofs are metal roofs with a covering built up of layers of tar and felt in which the first layer on the metal is a heavy layer of tar as an adhesive and vapor seal. Such roofs can provide a fast-spreading, self-sustaining fire if heated to 800°F for as little as five minutes.

1 studied the testimony and reports stemming front the 1973 Beverly Hills Supper Club fire in Southgate, Kentucky, which killed 168 people. I am convinced that all but two of the victims died of gases principally generated by a metal deck roof fire over the Cabaret Room, not the wiring insulation that was accepted in the lawsuits as the fuel.

I will continue my discussion of flame spread and fire growth in the next issue.

Brian Zaitz, Demond Simmons, and Dave Dubowski

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