You Can’t Get Away From Chemistry

You Can’t Get Away From Chemistry

Some basic rules for planning, attacking and cleaning up can help fire fighters handle hazards created by chemicals


Glassboro, N.J., State College

There are not too many professional chemists who are also professional firemen—nor professional firemen who call themselves chemists.

Still it is quite true that all firemen are practicing chemists. The chemist has a chemical reaction which goes; the fireman has a working fire. The words differ, but both the reaction and the fire operate on the same fundamental principles: matter is transformed and energy is released. It might be noted in passing that chemists are all too frequently fire fighters. The fire extinguisher is a necessary piece of scientific equipment.

There are two essential points to be made. First, fire and methods to control fire are chemical phenomena and follow certain fundamental laws. Second, many chemicals bum and their toxic nature adds to the hazard facing the responding fire fighter. Most of the discussion in this paper will dwell upon the second point, but the first should be mentioned at least briefly.

In a very simple sense, the combustion of carbonaceous materials (ordinary class A type substances) can be described as a chemical process which converts the carbon compounds into carbon dioxide and water. This is obviously not only simpleminded, but wrong. Anyone who has gone into a burning building and been hit by the usual irritating, choking smoke is well aware that the odorless, colorless gases of carbon dioxide and water may well be present, but many other substances are also there. Combustion is a complicated process. A variety of combustion products, including formaldehyde and acrolein, are present, depending upon the nature of the material burning, the temperature, air supply and other factors. Much is known about the process; much more is yet to be learned.

Importance of chemistry

The control of fire is a chemical process. Water can be viewed as a chemical, as can carbon dioxide and the various halogenated hydrocarbons.

The chemical powders, sodium bicarbonate, potassium bicarbonate, ammonium hydrogen phosphate and potassium chloride, are extraordinarily effective extinguishing agents. How they work may not be thoroughly understood, but they do work. New agents, such as Light Water foam are also the chemist’s contribution to the fire fighter’s arsenal. Thus, an understanding of the combustion process and the development of new materials to control fire are serious concerns of the chemist and of practical importance to the fire fighter.

But of greatest concern to the practicing fireman is the hazardous nature of chemicals themselves. At one time only those who were concerned with fires in major chemical plants or other such occupancies needed to worry about chemicals. Now, however, this is truly a chemical world. A variety of plain and exotic chemicals are being found more frequently, in larger quantities and under quite unexpected circumstances. Chemicals which some years ago were laboratory curiosities are now items of commerce, transported over the highways, rail lines and waterways of this country in multi-ton quantities. Many materials whose toxicity and flammability are extraordinarily high are found in such casual occupancies as the agricultural supply store, the supermarket and the metalworking shop. Certainly a good knowledge of chemistry, and chemicals themselves, is necessary if the job of the fire fighter is to be made safer and more effective.

The P-A-C concept

Chemistry and the fire fighter can be examined, for convenience, under the general headings, P-A-C, where P stands for planning, A for attack and C for cleanup.

Look first at planning, the P in P-A-C. In defining target hazards and in all good pre-fire planning operations, the presence of hazardous chemicals in a particular occupancy goes high on the check list. Chemicals appear these days in some strange places, and all too frequently not in occupancies labeled “XYZ Chemical Company.” Some years ago a dozen firemen in the Cleveland Fire Department suffered injury when chemicals used in a metalworking shop became involved in a fire, decomposed, and filled the building with the toxic products of their decomposition. Certainly the first step then in the planning process is recognition by the fire inspector or in-service inspection team of the potentially hazardous chemicals which may be found in a wide variety of occupancies.

Just what sort of chemicals need be considered? The obvious ones are those which, as liquids or gases, will bum and add to the severity of a fire. These are the common flammable materials.

Although hazardous liquids and gases are most common, due consideration must be given to flammable solids. Many of these resemble flammable liquids. Others, such as the organic peroxides, are potential explosives. Still others, particularly the finely divided metal powders, resemble flour or plastic dusts in their behavior in a fire situation; they burn explosively. Thus, a red flag for the inspector is the presence of cans of metal powder. Massive pieces of the metal may be of no hazard, but as fine powder, watch out. Aluminum, iron and nickel powders are not infrequently encountered.

Proximity hazards

The inspector must be concerned not only with what chemicals are present but also where they are stored. Chemicals are hazardous enough by themselves; unexpected combinations of chemicals can be disastrous. For example, a spill of nitric acid is a nuisance, but nitric acid spilled on sawdust can become an explosive combination. Accidents will occur, and chemicals do spill and come into contact with one another.

Another red flag for the inspector then should be the relative locations of chemicals. The question that he must ask is what would happen if these chemicals were mixed accidentally or knocked over and mixed by a poorly applied hose stream being used to control a minor fire. This is not an easy question and even a trained chemist may have trouble answering it, but certainly the probability of difficulty here must be recognized.

Good housekeeping and the separation of obviously incompatible chemicals—chemicals which would give trouble if mixed—reduce the possibility of trouble, and the inspector may well suggest these changes.

Although the flammable characteristics of materials certainly are uppermost in the mind of the fireman, an even more important consideration is the toxic nature of chemicals or of their decomposition products. Even a very small fire can release a major cloud of toxic gas which can spread throughout the occupancy and indeed, as was shown in Charleston, W. Va., can spread over an entire community, causing great physical and psychological discomfort to many. Particularly with the many new and exotic chemicals now readily available, the potential for toxic hazard must be recognized.

At the present time, there is no uniform labeling system that will tell at a glance whether a particular chemical is flammable or toxic and if so, just how great its hazard potential may be. The inspector must rely upon his own good sense, his experience and his suspicions. One good rule of thumb for the inspector is the generality that if a liquid or a gas contains carbon atoms as part of its molecule, then the material will burn. There are exceptions, and the obvious one is carbon dioxide, but the presence of carbon in the formula of any compound should set the red flags waving in the mind of the inspector and send him to his handbooks for more exact information.

Ask questions

The good inspector will recognize the limitations of his knowledge. He will know that not all the red flags will fly as he looks over an occupancy. He will attempt to overcome this limitation by asking questions about what might appear to be a most innocuous substance. The rules of thumb discussed above should trigger questions. The owner of the shop or plant should be asked first just exactly what he might know about the hazard of a particular substance.

It is important, however, that the inspector ask the right question. The right question is more frequently, “Hey, what’s that stuff over there?” not “Is that flammable and will it bum?” All too frequently the man being asked doesn’t know what a hazard potential his material is, or if he does know, isn’t about to tell, particularly if there is a potential code violation in handling or storage. Obviously, this isn’t applicable to the manager of a major chemical plant. Rather, this concern is with the small garage owner, the small chemical formulator, or the guy with the machine shop who really doesn’t know what he has in the tank, only that it works. Let us be quite realistic. Few companies roll on many major chemical industry fires, but quite assuredly, every fire company in the country will be responding to small fires in occupancies where chemical hazards are present.

Recognition of a hazard is one thing. Determining the degree of hazard and what to do about it is something else. For this information, you need expert advice, and this is most frequently found in books.

The National Fire Protection Association and others have a fine assortment of books, pamphlets and the like dealing with just exactly this problem. Start with Charles W. Bahme’s book on hazardous chemicals, “Fire Protection for Chemicals,” the National Fire Protection Association “Fire Protection Handbook,” and NFPA Manual 491-M should all be on the desk of any good inspector.

Fire attack

Now look at the second part of the P-A-C argument, the A for fire attack. Here, time is essential. It’s doubtful that there will be time to consult a manual. Immediately on the scene of a working fire, the chief officer must size up the situation. A chemical input into his thinking at this critical moment is absolutely necessary. The questions are really, “Just what is burning?” “What is its explosive hazard?” “Is it toxic?” “Has or is it going to give off dense clouds of heavy smoke that will make visibility and breathing difficult inside the building?” Or, “Is this a relatively straightforward type of problem which can be handled by following normal, standard operating procedures?”

Good pre-fire planning should give the answers. However, in the absence of this, there are certain clues which are helpful. The sign on the door is one. For example, if you are coming in on an agricultural supply shop you can well count on the presence of potent insecticides whose vapors can kill. Today, with all the chemicals used in processing fabric, even a clothing store fire will give gases and combinations of gases quite different from those encountered even 20 years ago. Once again, if you don’t know already, the important point is to ask and find out just exactly what is burning if there is any suspicion whatsoever that the fire involves something a little out of the ordinary.


Look for hazardous chemicals during inspections

Learn what chemicals are present

Find out how they are stored

Ask what can happen if they become mixed

Determine the degree of hazard

Get advice


What is burning?

What is its explosive hazard?

Is it toxic?

Will it generate blinding or suffocating smoke?

Keep to windward of toxic vapors

Keep distance from explosive hazard


Get expert advice

Carefully segregate unlabeled, scorched or otherwise suspicious containers

Remove toxic material from protective clothing

Red flags should go up at the mention of any of the organic compounds now found commonly in commerce. Again, as an example, be particularly alert to the mention of organic peroxides. Not too many years ago in Norwich, Conn., four firemen died when a mixed cargo of organic peroxides in a truck trailer became involved in a fire and exploded. Certainly, here is a red flag, but red flags also should go up during the fast size-up of a grocery store or on encountering a dip tank in a metal cleaning shop.

Water for extinguishment

Once the size-up is made, then the tactics of fire control and extinguishment must be brought into play. In spite of the advances in chemical science that have added new weapons to the arsenal of the fireman, it is almost inevitable that for any fire of any size, the basic extinguishing agent is going to be water. Whether the fire involves chemicals or whether it involves a regular Class A type is not that important. The fireman is going to work with the material he has at hand. His tools and his equipment are all designed for use with water, and that is what is going to be used.

Here, the process by which water is applied and the location of men are important. If there is high probability that toxic vapors will be given off, keep your men on the windward side of the fire. If there is explosion hazard, keep them far enough away so that, should something go wrong, they will not be involved in the blast. Then set up and go to work. It may well be necessary in order to protect the safety of the men involved that the hard hitting, “Let’s go in and get it, boys!” type of approach to fire fighting is not going to be appropriate. Instead, it will be necessary to back off, set up master streams and control the fire from this vantage point. Unhappy as this may be for all good firemen, it may well be the only answer that will keep both men and other occupancies protected in such a way that the fire can be controlled without needless and useless loss of life.

Cleanup dangers

Finally, it is necessary to look at the last letter in the P-A-C argument, the C for cleanup. Sometimes it really might be better if the fire department let the building bum down, protecting exposures, rather than making a quick stop and being left with a very nasty cleanup operation. Admittedly, this is bad practice. It’s not being advocated, but only offered to drive home the point that the problems of cleanup are at best miserable and at worst intolerable.

Nicely labeled and uncontaminated, fresh in their containers, most chemicals are quite innocuous. With the label washed off after exposure to unknown conditions of heat, mixed on the floor with substances unknown, or floating in a pool of water, these same chemicals can be a tremendous hazard. If at all possible, get expert advice before moving in for final cleanup and overhaul. The standard procedure of throwing everything out in a big pile in the backyard can trigger even more trouble. The owner or manager should be on the scene, and representatives of the chemical supplier should be asked for advice. Time is not as critical an element here.

The manufacturer may well send an expert to the scene. State agencies may be able to supply trained personnel. Important again, however, is the need to ask for help and then to take the advice when it is given.

If no help is available, or local conditions require more rapid action, it is necessary to move with great care and caution. Unlabeled, scorched, or otherwise suspicious containers should be carefully segregated well away from other exposures. Secure the area, post a watch, but don’t try to restore the premises to any semblance of order.


There is still another important part of the cleanup process, and that involves the decontamination of personnel and equipment after exposure to toxic materials. Following procedures quite similar to those which are used after exposure to radiation hazards, it is necessary to decontaminate before leaving the fireground. The outside of a pair of boots or a turnout coat can be loaded with poisonous materials. It is necessary to scrub down these articles of clothing and other equipment, to wash and wash again. Ask for advice on final decontamination and then follow this advice, even if it means throwing out the garment or tool.

There are many chemicals in common use, particularly among the newer insecticides but not limited to them, that can harm one long after the original exposure is made. Small quantities of these substances on the handle of an ax or on a pair of gloves can be transmitted on the next use to the skin and from there into the body. Once again, caution and the need for expert advice are the watchwords.

Changing world of chemistry

To summarize, this is a chemical world and it is a changing world. Some of this change is positive as far as the fire service is concerned as new extinguishing agents are made available, although the fire service is still a long way from a time when a young boy can be dispatched to a working fire with a jar of some magic chemical that can be thrown on the fire and effect extinguishment in one easy stroke. Over the past several years, the number of new weapons in the arsenal of the fire fighter has increased, and increased tremendously, thanks to chemical research.

Other changes in this world are quite negative, however. New toxic and highly flammable materials appear, appear in much larger quantities than one would ever expect, and become articles of commerce on highways, in supermarkets, in the back room of garages, near swimming pools, and throughout areas which one would ordinarily not expect to consider as chemical occupancies. One thing, however, is constant in this changing world: mistakes are still going to be made and fire departments are still going to be called to the scene of other people’s mistakes to correct them.

Good fire prevention activities will reduce the number and severity of these mistakes. Well-trained inspectors and men on in-service inspections can identify hazards and, without the pressure of an emergency situation, call in experts for advice and counsel. They can read books and pamphlets. The corner druggist has enough chemical training to be a useful resource. The state fire marshal’s office can resolve a problem. The local experts are there, but it is necessary to know who they are and how to reach them long before an emergency occurs. When that emergency does strike, set up, be on the guard for chemicals and be particularly alert for toxic materials and smokes. After having determined that there is no hazard to life within the occupancy, protect your own men. Until such time as there is a generally accepted foolproof system of warning signs, it is necessary to assume the worst and work accordingly. At cleanup, disturb the scene to a minimum, and again get help and expert advice.

The fire service has always responded to new situations with courage. It’s now time to respond with chemical knowledge as well.

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