Misconceptions concerning safety to life from fire

Misconceptions concerning safety to life from fire

SOME 12,000 PERSONS lose their lives in fires each year in the United States. This fact was hardly cause for widespread public indignation until December 1, 1958. The disastrous fire that afternoon at Our Lady of Angels grade school in Chicago, in which 92 children and three nuns perished, set off an emotional tidal wave that swept across Chicago and into every school in the United States. The tidal wave is still moving. But corrective action, out of all this emotion, is plagued with confusion, misunderstandings, misconceptions, and red tape.

A month and a half after the disaster, the Chicago City Council passed an ordinance requiring the installation of automatic sprinkler systems in all existing schools of brick, ordinary joist or poorer construction, which were two stories or more in height. Along with this went a requirement for connecting manual fire alarm systems in all existing schools to city fire alarm boxes.

A month or so later, upon recommendation from the Coroner’s Jury, the Mayor’s Advisory Committee on Building Code Amendments recommended to the city council that some 22 additional fire safety features be enacted into law and applied retroactively to all existing school buildings. Public hearings were held on these additional amendments to the municipal code and testimony was taken from representatives of both the parochial and public school systems, appropriate municipal officials and other interested parties which included spokesmen from various special interest groups in the building construction industry. The end result of these hearings was a mass of confusing and contradictory testimony on what fire safety features would be required to insure that such a school fire disaster would not be repeated.

Professor Maatman graduated from Illinois Institute of Technology in 1951 with a B.S. degree in Fire Protection and Safety Engineering. His experience includes service with the Coast Guard where he was Fire Protection Officer for the Captain, Port of Los Angeles; and six years with the Illinois Inspection Bureau where he concentrated on sprinkler engineering and inspection and municipal fire protection engineering. In 1956, he became assistant chief engineer of the Bureau and served in that capacity until his appointment to the Illinois Institute faculty in 1959. He is a member of the Society of Fire Protection Engineers and serves that organization on its engineering education committee. He is also a member of the N.F.P.A. Membership Committee.

For example, opinions ranged all the way from recommending complete removal of all combustible interior trim, to flameproofing all of it, to suggesting that no further requirements were necessary because there was already an ordinance requiring complete automatic sprinkler system installations in existing schools!

Is it any wonder that municipal officials are at a loss when it comes to determining what specific fire safety regulations are necessary to provide reasonable life safety—yet not involve prohibitive expenditures. It’s high time we clarify this controversy, and make certain that we place the various proposed fire safety features in perspective.

First of all, the Our Lady of Angels school fire was not the first large-loss-of-life fire nor, unfortunately, will it be the last of such disasters although an enlightened and dedicated effort can do much toward correcting the structural as well as human errors which make them possible. The records of all agencies which collect fire loss statistics include numerous examples of large-loss-of-life fire disasters down through the years. To name just a few of the more prominent ones, we need only to go back to the Iroquois Theater fire of 1903 in Chicago when 602 persons perished or the Lakeview School fire of 1908 in Collinwood, Ohio, where 175 children died. In more recent years, we have experienced the Cocoanut Grove Night Club fire of 1942 in Boston where some 492 persons died, the Winecoff and La Salle Hotel disasters of 1946 which contributed a total of 180 dead, and within the last two years, a nursing home fire in Warrenton, Mo., which accounted for 71 lives. The pattern of these fires has been basically the same and has taken place in every instance in a setting composed of a large concentration of human beings occupying a building that was built to spread fire.

Delayed discovery

The development of these fires has usually been along the following lines: A fire starts in one of the lower levels of the building and gains considerable headway before it is discovered or, in some cases, due to panic or the lack of adequate instructions after the discovery of an incipient fire, an alarm is not immediately transmitted to the fire department nor to the other occupants of the building. In either case, the fire has reached considerable intensity before the fire department arrives at the scene.

In the meantime, fed by the combustible contents found within the building and, in some cases, by the combustible materials forming a part of the structure or interior trim, the fire quickly intensifies, fanned by the natural flue effect of open stairways and other unprotected vertical openings. The latter two are undoubtedly the most hazardous common factor in all large-loss-of-life fires involving multistory buildings.

The hot gases and smoke which precede the fire in its upward spread soon convert the corridors and open stairways into a veritable death trap. A short time thereafter, any exposed combustible materials located in the upper corridors and stairways have been raised to their ignition point and break out in flame, further adding to the intensity of an already humanly unbearable situation.

This has sometimes led to the mistaken conclusion that the simple elimination of any combustible finish in the stairways and corridors will provide the necessary safety factor. The fallacy of this conclusion was demonstrated in the 1959 series of fire tests in a Los Angeles school building where lethal temperatures and smoke densities were prevalent throughout the corridors before the combustible acoustical ceiling finish became involved.

If the Los Angeles test school fires were an actual emergency the occupants of the upper floors of the building, initially unable to use the corridors and interior open stairways because of the hot gases and smoke, would most likely find the conditions within the rooms unbearable as actual flaming occurs in the corridor. And those who cannot reach an exterior fire escape from their window, or cannot be rescued by fire department ladder equipment, either perish within their rooms or are killed, or seriously injured, by leaping from upper stories. Those persons located within rooms equipped with ordinary glass transoms most probably succumb to the effects of smoke and hot gases several minutes before the others, and, in many cases, even before actual flaming occurs on their floor level.

Slight variations

This story might vary a small extent from time to time but the same essential ingredients are usually always present: (1) Delay in discovery and/or delay in alarm transmission which in either case prevents early fire department rescue or extinguishment efforts; (2) open stairways and/or other unprotected vertical openings in multistory buildings which promote fire growth, and more important, quickly allow the entire access areas of the building to be filled with smoke and hot gases, cutting off the occupants from the use of the interior exit facilities (which may or may not be of adequate capacity); (3) the use of highly combustible interior trim and decorations which provides a media over which the fire can spread more rapidly and which is particularly subject to “flashover” or premature ignition before the main fire has progressed to a given floor level. This factor is obvious in one-story buildings such as the Cocoanut Grove Night Club where highly combustible decorations and synthetic leather wall coverings spread the fire rapidly throughout the structure.

As previously mentioned, the most important single contributing factor to large-loss-of-life fires has been without a doubt the lack of protection for stairways, elevator and dumbwaiter shafts, air conditioning and ventilating ducts, furred and concealed spaces and other vertical openings which pierce floor levels.

With proper enclosure of not only the required number of exits but also of all vertical openings, a delay in discovery and/or alarm transmission, or the presence of combustible trim in a multistory building, will not endanger occupants on floor levels remote from the fire for a considerable length of time.

This factor was brought out forcibly in the Our Lady of Angels fire. In this instance, there was a delay in discovery of the fire and an additional delay in notifying both the fire department and all occupants of the building. Yet despite the precious minutes lost by both these delays, and the presence of acoustical ceiling tile and other combustible trim in the first-floor corridor of the north wing of the school, all of the students on this floor level were able to file out of the exits at the front of the building simply because the rear stairwell, where the fire originated, was cut off from the first-floor corridor by an approved Class B fire door. Thus it is clear that the complete enclosure of all vertical openings and the provision of adequate exit capacity can in itself minimize or localize the life safety hazard to only that section of the building where the fire originates.

However, as it is obviously desirable to even further minimize the life safety hazard, it is appropriate to consider further measures to cut down the delay in discovery and transmission of the fire alarm to the fire department and the occupants of the building. As past experience has indicated that dependence cannot be placed on early-human detection, it is necessary to turn to some type of automatic fire detection system.

The automatic sprinkler system, which has achieved an enviable performance record in this country, appears to fill the bill very adequately. This system not only provides for early local detection of a fire, but in addition, can be arranged to transmit an alarm to the municipal fire alarm headquarters. Also, the system serves the important dual role of an extinguishing agent in that its operation will extinguish the fire or at the very least hold it in check until the arrival of the fire department.

An alternate proposal which has been advocated by some authorities is the provision of an automatic heat-actuated fire detection system in lieu of a sprinkler system or in combination with a partial sprinkler system installation. If all vertical openings are enclosed, this writer can see no objection to this alternate method of protection, other than to point out that the advantage of a combined detection and extinguishing system would not be obtained by the first method and would be a matter of an educated guess with the second method.

If all vertical openings are protected and an automatic sprinkler system is provided, combustible interior finish and trim become less important simply because the ability of a fire to develop and spread has been seriously curtailed. This feature is recognized in both the National Building Code of the NBFU and the NFPA Building ’ Exits Code which lessen their restrictions on interior finish to have a flame spread not in excess of 200 in corridors, exitways and rooms of over 100 persons capacity while normally these must be restricted to a flame spread not in excess of 75.

Restrict fire spread

If the building, due to its construction or low height, is not required to be sprinklered, then it appears reasonable to restrict somewhat more the use of combustible interior finish. Both the NFPA Building Exits Code and the National Building Code recognize this factor and require that the interior finish of walls and ceilings of corridors, exitways and rooms of over 100 persons capacity have a flame spread rating not in excess of 75 except for an allowable aggregate area of 10 percent which is permitted to have a flame spread rating not in excess of 200. Other portions of the building are allowed to have interior finish with a flame spread rating not in excess of 200.

One of the most common types of interior finish found in school buildings today is acoustical ceiling tile. There are two basic types which are manufactured in this country, one of which uses a mineral or gypsum base and is essentially an incombustible material, and the other which is composed mainly of cane or wood fibers processed into board forms and which is combustible. The incombustible type, has a U.L. flame spread rating of from 5 to 20, depending on the particular manufacturer and on the character and arrangement of the backing supports and easily meets the flame spread requirements for required corridors and exitways in unsprinklered buildings.

Continued on page 992

Continued from page 960

The combustible type varies in flame spread characteristics. Some of the older types of tile, especially where they have been in service for along period of time, undoubtedly have a flame spread rating in excess of 200. However, since 1953, the insulation board industry has standardized on a procedure of applying a factory finish coating to the exposed face of all combustible tile which has consistently given test results of less than 200 flame spread (standard tunnel tests conducted by Southwest Research Institute). This type of tile may be considered as satisfactory for installation in sprinklered schools or in those areas of unsprinklered schools which do not require a rating of 75 or less as long as it is applied directly to a solid incombustible support. However, if the tile is fastened to nailing strips, or in such a manner as to create a concealed space on the back side, then adequate fire stopping must be provided to restrict the possibility of fire spread on the unexposed uncoated side, as required by modern building codes.

It is also possible to apply one of various U.L.-approved fire retardant paints to combustible acoustical tile to reduce its flame spread characteristics below 75. This can be accomplished if the tile has at least 1/2-inch nominal thickness and is fastened directly to a solid incombustible surface or otherwise properly installed and fire-stopped on its back surface. Thus, it is possible to treat a considerable amount of the combustible tile already installed in existing school buildings to such an extent that it will meet the interior finish requirements for corridors, exitways and large-capacity rooms.

In certain instances, it is not physically possible, or economically or functionally practical, to enclose all stairways in existing school buildings. In such cases, it is imperative that a complete automatic sprinkler system installation be provided or a direct exit to the outside for each classroom be provided. Results obtained from the Los Angeles tests indicate that a fire occurring in a building having open stairways and only partial sprinkler protection develops sufficient heat, smoke and steam in corridors to make them untenable within a few minutes in those cases where no sprinkler protection is available over the seat of the fire. These results confirm what many fire protection engineers have always maintained that a partial sprinkler installation gives only partial protection to the building and questionable protection to the occupants.

Alternate egress important

Because of the difficulty in achieving adequate sprinkler system maintenance in schools or other public buildings, and because of the possibility that a smouldering fire might give off considerable smoke before sufficient heat is built up to actuate the sprinkler system, it is important that an alternate means of egress be provided for all occupants in such a manner that they will not have to traverse through the open corridors and exitways to reach the outside of the building. This can be accomplished by providing doors between adjacent classrooms which give access to exterior fire escapes and/or to any enclosed interior stairways which can be utilized.

Experience has shown that most large-loss-of-life fires have been caused by several independent factors—not one. Prominent among these have been delayed discovery, a combination of several structural deficiencies, and a lack of proper instruction to operating personnel regarding evacuation and fire department alarm transmission. All these factors must be recognized, and adequately cared for by an enlightened public. It’s time to implement the knowledge we have, for constructive action.

No posts to display