Chemical Fires and How They Should be Handled
Hazards Due to Chemicals—Prevention of Such Fires—The Storage of Chemicals — Fighting Chemical Fires — Poisonous Gases
THE following report by the chemical fire committee of the Indiana Section, American Chemical Society, which represents research and experimental work covering a period of about six months, was made largely for the benefit of the Indianapolis, Ind., fire prevention bureau, of which Capt. Jacob E. Riedel is chief. The report, however, contains very important information as to the hazards of chemicals in firefighting.
The committee has spent considerable time and thought on the matter of chemical fires. An extensive correspondence has produced a rather small amount of collected data on the subject. We have therefore summarized the experience and knowledge of the men composing the committee and added to it information from a number of sources. We are presenting it to you as an outline, expecting that inspections will develop questions not covered in this report. We welcome this opportunity to serve you and shall be very glad to co-operate with you at all times, either in emergencies or in connection with surveys.
Fire Hazards Due to Chemicals
The most hazardous industries are best protected. Accidents including fire, occur seldom and fighting procedures are determined in advance. Every safeguard is employed. It is the small plant where experts are not employed, and where misinformed and inferior workman fail to appreciate the protective requirements of their operations.
Nearly every fire is a case by itself. Care in storing will prevent most fires caused by the action of chemicals. Fires in chemical storehouses may originate from other causes and be increased and fed by chemicals, which, under heat, yield combustible gases. Poisonous gases may he evolved. Dangerous mixtures of chemicals occur during a fire due to broken containers. But it should be understood particularly that poisoning or personal injury from stored chemicals is possible in very few fires.
Knowledge of spontaneous combustion is fairly well disseminated. It is action caused by oxidation of organic matter. Such action is progressing at all times everywhere. Actual fires results only when certain occasional conditions permit or aid very rapid oxidation and consequent rises in temperature to the ignition point of the material.
The role of oils is well known in this connection. Many plants employ usually harmless materials in manufacturing processes. A change in procedure or personnel may result in a dangerous mixture of chemicals harmless by themselves. The fact that dangerous and semi-dangerous materials are handled day after day with no accident is often due, not to care, hut to chance which has not provided just the right combination of circumstances to produce an accident or fire.
The Prevention of Fires Caused by Chemicals
Careful inspection of manufacturing plants using chemicals in processes and of drug and chemical dealer’s warehouses will result in improved conditions as well as inform the fire department of the location of special hazards.
Such an inspection should disclose the kind and quantity of material and how it is used or stored. Some industries are covered by special legislation. Dyers and cleaners operate under a model law. Yet small establishments spring up unnoticed and pressing shops may at any time use dangerous methods of cleaning. Sponging and spotting of clothing and hats is carried on near open fires and electric motors and by smokers. The operation may result in the development of static electricity. Passing a radiator or supply pipe with a charged garment may result in a spark explosion. Only the fear of unexpected inspection and prosecution can hold such shops in line. The small pressing and hat cleaning establishments require constant watching. Poisonous gases will be encountered seldom. For the most part their presence is easily detected by their strong odors. In the case of nitrate fires, a gas may be evolved which may produce unconsciousness without warning, since its odor is slight. The same may be said of carbon monoxide, which may be produced by any fire confined in a closed place. It is a product of incomplete combustion and the cause of “Backdraughts,” which occasionally occur when windows and doors are broken in a burning building.
Fire Producing or Aiding Chemicals Which May Be Encountered Frequently
Fire Producing or Aiding Chemicals Which Will Be Encountered Very Seldom
Oil of animal or vegetable origin is particularly subject to rapid oxidation. Paint mixing and manufacturing operations involve the use of large amount of such oils. These industries often occupy buildings of non-fire-resistive construction and untidy workmen allow oil soaked trash to accumulate.
Paint manufacturers are using increasing quantities of volatile inflammable liquids as drier substitutes. Oils are used in the preparation of sweeping compounds. These may be stored in heated and confined places in office buildings as well as in dealers stocks.
lacquers all contain an inflammable vehicle. Metal bed, chandelier, and bric a brac refinishing shops frequently contain explosive air mixtures.
In handling new as well as reclaimed rubber, quantities of inflammable liquids are employed. Large establishments provide safeguards against explosions by maintaining a high humidity at the dangerous points. Smaller plants often have no knowledge of such procedure.
Storage of Chemicals
Fires which occur from chemicals and the danger encountered in fighting fires where chemicals are near at hand, may be largely prevented by using certain precautions. The proper storage of chemicals both as to location in buildings and in respect to one another is one of the most effective preventive measures. In arriving at what proper storage means, the type and quantity of a substance must be considered likewise the different types of material that are stored near each other.
Inflammable liquids such as gasoline, benzine, naptha, chloroform, ether, carbon disulphide, etc., should be stored in a separate room and at one end of the establishment. The floor of the storage room should be tight and ventilation secured by a vent through the roof.
Liquid acids in breakable containers of over one-half gallon size should be packed with mineral wool. In no case should hay, straw or organic material be used. They should be stored by themselves on the ground or basement floor so that drainage from broken containers will reach a sewer promptly without coming in contact with organic material or other chemicals.
Niter and all nitrates should he stored in metal or glass containers (never in cloth or paper) and should be kept dry and away from heat. During hot, damp weather fires may start in these materials spontaneously. In moist places particularly, nitrates should be at a distance from radiators, stoves and steam pipes. No other chemicals should be stored near by nor handled in such manner that spillage may occur into the nitrates. Sulphur, chlorates, dichromates and permanganates especially should be kept away. These materials are generally quite safe alone but mixed with organic matter or other chemicals may explode or burn. They should be isolated and stored with care. Even metals such as powdered iron, aluminum, magnesium, etc., should be kept in metallic containers in relatively small portions.
Sodium and potassium must be kept under oil or in vacuum. Phosphorus must be stored under water, and all three of these substances located for easy removal from the building in case of fire. As a safe-guard, these materials should be kept in double containers, the outer one being water-tight and nonbreakahle, with non-combustible packing between the two. The packing should be saturated with the same liquid that covers the chemical
Hypochlorites mixed with fully divided combustible matter have been responsible for very serious fires. This danger is so great that steamship companies refuse such material except where it is packed with great care.
Certain chemicals mixed with sulphur ignite the latter with friction. If such mixtures occur on floors walking over them may cause an explosion and fires. Sulphur particularly should be handled without spillage.
Methods of Fighting Chemical Fires
Chemicals enter into consideration when they are located in a burning building even though they have nothing to do with the origin of the fire, since they may be aids to combustion if not actually combustible themselves.
It is well known that water spreads a gasoline fire. It may also result in increasing and spreading a fire in oils and volatile liquids of lower specific gravity than water. Smothering extinguishers are indicated for such fires as may occur in paint, oil, and gasoline, or almost anywhere around a gas plant.
A covering of sand or other inert solid material is most effective on burning sulphur. Water on nitrates is effective if the temperature is lowbut as in the case of sulphur it may be so high that w’ater is converted into steam with an explosion before it reachs the real seat of the fire. A smothering extinguisher is only partially effective, however, since oxygen is supplied by nitrates themselves and a thorough saturation with water or carbon tetrachloride is required to stop oxidation and burning. If possible, isolate or remove the unburned portion of the stock. There is no danger of an explosion from nitrates alone but poisonous gases may be present. In acid fires water is perhaps best. It will not only extinguish the fire but dilute and render the acid less active and injurious to the clothing and the person of the fireman.
Oil and gasoline storage tanks are well constructed of heavy material. Fires occur only at the surface where oxygen is available. The material itself supplies no oxygen for combustion. In many cases the fire bums in a partially filled tank until the oxygen is exhausted when it extinguishes itself. Danger of explosion is remote. Surrounding structures should be protected and the usual smothering extinguishers applies to the fire.
Metallic sodium and potassium, peroxides, etc., that explode violently or fire in contact with water will be found usually only in chemical laboratories and chemical manufacturing plants and there in rather small quantities. They are so active, and produce such high temperatures that we have recommended that they be located for easy removal from a building in case of fire. Carbon tetrachloride would stop their burning if it could be applied. However oxidation or burning, is so explosive and violent that it would be very unlikely to be effective. Such material must burn itself out which it will do very rapidly, exploding and throwing pieces of itself which fire combustibles on which it may fall. It should be emphasized that water may be a most dangerous and ineffective extinguisher in chemical as well as some other fires. Except in material containing available oxygen, such as nitrates, a smothering with inert and non-combustible liquids or solids is most effective.
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How Chemical Fires Should Be Handled
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Many of the fumes produced with be heavy and seek low levels except as they are carried along by hot air. Your attention should be called to the report of the bureau of mines which finds that a poisonous atmosphere may be produced by using carbon tetrachloride on a fire in a confined place. Adequate ventilation should follow its use and men kept in such a place for short periods only.
Fires in warehouses containing compressed gas in cylinders may result in breakage and the release of explosive of poisonous gases as the case may be. Broken hydrogen or acetylene cylinders would result in heavy explosions. Liberated oxygen would feed the fires already burning. No special treatment of such a fire is available. Usual methods to confine and extinguish the fire should be used. As the temperature of the cylinder of gas rises, the internal pressure increases enormously. If possible keep the fire from the cylinders and keep them Cool.
Gas masks or filters are effective only with low concentrations of poisonous gases and where there is oxygen remaining in the air. In most fires, where gases are evolved, only oxygen helmets are effective, since the oxygen content of the air is nearly exhausted. With the breakage of chlorine or ammonia cylinders, the air is so heavy with the gases that oxygen helmets must he used. These devices are to be recommended for use only after long and thorough training, when confidence in and familiarity with them is developed.
Continued thorough inspection is essential to keep the fire department informed of conditions and to correct those which are dangerous.
The proper type of fire extingusher should be chosen for the particular case at hand, located and maintained in readiness for use.
The absolute prohibition of the use of inflammable liquids and the storing of large stocks of oxidizing chemicals in the congested value district is recommended though we recognize that this would effect some large industries. Financial responsibility should rest on the man who maintains a fire hazard.
Since materials may be relocated in storage and process of manufacture develop temporary hazardous conditions, we believe it advantageous to have contact with two men in each establishment who will always be informed as to stocks and factory operation and have knowledge of probable contingencies in case of fire. These men should be issued cards or badges passing them through the fire lines at their plant, where they should report to the officer in charge giving him all possible information and assistance.
In case of gas poisoning it is essential that the men be given proper treatment promptly. We believe that connections should be made with physicians specially informed along each line since it is a type of accident only occasionally encountered and with which most practitioners are unfamiliar.
Manufacturers observing the following rules will materially reduce their fire losses.
- Keep chemicals from moving parts of machines.
- Clean machines thoroughly before a different chemical mixture is introduced.
- Confine volatile inflammable solvents in closed systems.
- Store all chemicals separated from each other.
- Keep stocks in such a manner that spillage of one into another is impossible.
- Provide adequate floor drainage in acid storage rooms.
- Install a reliable sprinkler system.
- Protect sodium and potassium from water in case of fire.
- Arrange stocks of particularly dangerous material for easy removal from the building.
- Acquaint your fire chief with your premises and especially with your stocks and operation.
INDIANA SECTION OF THE AMERICAN CHEMICAL SOCIETY.
C. K. Calvert, Chairman, H. E. Corey, Wm. Higburg, Walter Kiplinger, D. R. May, E. W. McCullough, Paul Smith, V. A. Trask, Committee.