The Cause, Prevention and Control of CONFLAGRATIONS
Los Angeles F.D. photo
SOME 900,000 building fires occur in the United States every year, in which about 11,500 people lose their lives. But few of these fires ever reach the conflagration stage. Those caused by lightning, earthquake, volcanoes, flood, high winds, etc., have been responsible for the great losses. And, while man was not the cause, it was generally man’s failure to provide the means of protection and control that allowed such fires to become conflagrations.
The National Fire Protection Association lists 133 major conflagrations in American cities during the period between 1900 and 1950. They include such well-known ones as the San Francisco fire in 1906, which destrayed 28,000 buildings worth $350 million, and the Texas City fire of 1947, which cost $67 million in damage.
Large-loss fires are not as often reaching conflagration magnitude, as shown by the fact that in the 20-year period from 1921 to 1940, there were 55 conflagrations, while in the next 20 years there were only 37.
Now let’s look at the cause of these fires that do reach the conflagration stage. The initial cause of a conflagration is a fire, and a fire is either caused deliberately, accidentally, or negligently. Most fires are caused by carelessness. Leading among the common causes are men, women and children through their use of heating and cooking equipment, and because of carelessness with matches and smoking materials. However, there are two principal reasons why an ordinary fire jumps into the conflagration class. The first is the availability of a large amount of combustible materials over a wide area. The second is the lack of adequate means to interrupt the fuel supply once the fire gets started—lack of fire protection forces, fire breaks, water supply, heavy stream appliances, lack of access, and so on.
But in addition to these two primary reasons, many other factors contribute to a conflagration. Most of the time several of these factors are present. All of them prevail at one time or another, and they include: high winds in excess of 30 mph; inadequate water systems; lack of exposure protection; inadequate fire suppression forces; combustible construction, including combustible roofs; unusually hot and dry weather conditions; low humidity, and other factors.
There are many types of conflagrations: First, those which start in hazardous occupancies, or in the “fire breeders”in congested sections, which spread in one or more directions before effective resistance can be organized to bring them under control. These fires usually spread first to nearby properties lacking exposure protection; jump across streets by hneans of radiated heat; and then continue to spread in the direction the wind is blowing. Failure to control such fires is often due to a lack of sufficient water supplies, heavy-stream appliances, automatic sprinklers and protected window openings.
A second type of conflagration is one which occurs primarily in a residential section; then spreads beyond control, due to closely built combustible construction. A good example is the Bel Air, Calif., fire in 1961 where over 500 buildings worth about $40 million were destroyed. In that fire there was not only a continuous path of combustible homes, but gaps in between were full of tinder-dry brush.
A third type is one which starts out as a wildland fire in a forest or brush area and then enters a town over a wide front. This situation occurred in the Berkeley, Calif., conflagration of 1923. The people who excavate foundations for new buildings in that city still occasionally dig into old gas mains that were abandoned after that fire.
A fourth type of conflagration arises out of a large explosion. The Texas City disaster of 1947 is an example. Here, a ship, loaded with ammonium nitrate fertilizer, blew up—wiped out the whole fire department—along with about 500 other people. And flying debris started fires in oil storage tanks as well as in the nearby industrial and residential areas.
Keeping fires small
What can be done to prevent these conflagrations—to prevent fires, which may start out small, from reaching the conflagration stage? Certain factors such as high winds and hot, dry weather are present in most conflagrations and cannot be prevented. However, there are measures that can improve conditions which man controls. These include segregation of hazardous manufacturing operations, removal of dangerous structures in congested districts, and development of wide streets and park areas to facilitate fire fighting and to serve as fire breaks.
City officials should try to obtain a high standard of new building construction, particularly in high-value districts; encourage the elimination of combustible roof coverings, and the protection of wall openings in closely built structures by use of wire-glass windows or shutters and automatic sprinkler systems. The records show that many industrial fires have not developed into conflagrations because automatic sprinklers successfully protected the exposures.
Another thing to be done is to get rid of the so-called “conflagration breeders”—those very old dilapidated structures and those in which extremely hazardous processes are carried on. Whenever these are discovered, effort should be made to have them removed or restored to a safe condition, especially in highly congested districts.
Insofar as prevention of conflagrations is concerned, we can and must try to keep fires from starting in hazardous areas where they can quickly spread. And, assuming that they may start anyway, we can and must have them discovered and reported as quickly as possible by a reliable alarm system. Or better still, kept under control by an automatic extinguishing system. At the very least, we can try to have the most hazardous areas subdivided, both horizontally and vertically, to limit the probable spread of fire. In addition, we must urge protection of all openings and exposures to confine the fire as much as possible.
Now as to fire control itself. Obviously, the bigger fire you have the more difficult it will be to control. And the size of the fire will depend a great deal upon the physical conditions in the city or area under consideration, as well as upon the structural conditions and the fire defenses.
The physical conditions of most importance to fire control are the weather and topography. A correlation study of fire and weather data in Raleigh, N. C., showed that the days favorable to fires are those with a relative humidity factor equal to or less than 40 percent, a precipitation factor equal to or less than one hundredth of an inch on the day of the fire and for three preceding days, and a maximum wind speed equal to or more than 13 mph.
The Bel Air fire confirmed this finding. On November 6, 1961, the day of the fire, the humidity dipped to 3 percent and winds ranged from 25 to 50 mph. From January 1961 until the time of the fire, only 2.8 inches of rain had fallen.
As for topography, naturally it will make a difference on fire control whether the terrain is hilly or flat, and whether or not there are natural fire breaks such as rivers, lakes, ponds, canals, etc. Even man-made fire breaks, such as streets, freeways, railroad tracks, parks, and areas of fireresistive construction, can make a great difference, providing the wind is not too strong. If flying brands are dropping a mile away, then even a broad highway won’t stop the fire. Of course, it is desirable to have streets of sufficient width to maneuver fire equipment and still permit the evacuation of residents.
Structural conditions also have an important bearing on your ability to control a fire. Naturally, it will be more difficult if the building density is high and if the predominant construction is of combustible materials; especially so, if all the structures are in close proximity to brush or dry vegetation.
Now let us consider some of the important elements of fire defense. First, a look at the water supply. In spite of the fire fighter’s best efforts, fire will sometimes get away from the building of origin and spread to nearby exposures. In such a situation one of the best ways to prevent a fire from becoming a conflagration is to concentrate a sufficient number of powerful streams to cut the fire off where it is making the most headway. This requires water—lots of it! Therefore, it is obvious that it is important to improve the public water supplies, including the elimination of small and dead-end water mains.
In designing these water systems or improving them, remember they need to provide not only the water necessary for the ordinary fires in that area, but they also need to provide that water while the residents are making a maximum demand on the system. On top of that, all electrical lines providing power to water pumping stations should be run underground, to eliminate the lines being burned out or knocked down by high winds. Diesel standby engines should be provided to operate these pumps, if the electricity is cut off for any reason.
And, it’s a good idea to develop and catalog all auxiliary sources of water supply such as ponds, rivers, canals, and swimming pools; and also to obtain good access to these auxiliary sources for your fire equipment. Some of these sources you won’t be able to drive to.
Los Angeles found, for example, that the best method for getting water out of a swimming pool was either with a small portable pump, several of which we now carry on a special brush fire rig, or through ejectors or siphons, which we now carry on all apparatus in the mountain area.
In addition to an adequate and reliable water supply, no fire defense would be complete, of course, without a good fire department. It goes without saying that every effort should be made to improve the effectiveness of fire department operations by maintaining a sufficient number of well-designed fire apparatus to cope with greater-alarm fires. Equipment should provide: an abundance of heavy-stream appliances and mobile tank units; helicopters for use in appraising the fire situation from the air; arrangements for aerial tankers to make water drops; arrangements for bulldozers to work ahead of the fire, preparing fire breaks.
Moreover, this apparatus should be manned with enough professionally trained firemen to operate it in an effective manner. Today many fire departments are operating with a lack of adequate fire equipment. Others have adequate equipment, but are operating, through a false sense of economy, with inadequate manpower. When conflagration becomes a reality, the adequate manning of equipment with trained fire personnel could make the difference between complete destruction and making a good stop.
Cities and fire jurisdictions, which claim they save money by scanty manning of their fire departments, are only setting the stage for another “design for disaster.”
But good manning, without proper supervision, is not enough. Lines of authority should be well established and sufficient officers should be available to command all sectors of the emergency. An emergency operating procedure is most essential to automatically take care of the many routine functions necessary to coordinate all agencies involved. This leaves the officer in command with time to survey the fire situation and to formulate the tactical plans for fighting it.
It’s important that an emergency operating procedure be developed, whether it’s in one jurisdiction, or whether it be in a mutual-aid fire protection district. Such a plan could provide for augmenting manpower in time of a great emergency by recalling all off-duty members and obtaining assistance from surrounding departments. But there must be an overall disaster plan, or confusion will prevail when the conflagration occurs.
The State Fire Disaster Plan provides for the establishing of a procedure which can be used when a conflagration occurs. It is sufficiently flexible to permit the exercise of reason and judgment by responsible officials, and is based upon the principle of mutual aid.
In our department we have such a plan, and it’s constantly undergoing revision. After each major fire it is reviewed and amended as a result of our experience. Incidentally, “experience” has been defined as that something which enables you to recognize a mistake when you make it again. But we like to think that our experience will keep us from making future mistakes.
Condensed from a speech given at the annual conference of the California Fire Chiefs’ Association, May 20, 1965, Palo Alto, Calif.
To be continued