Gases, Chemicals and Hazardous Materials

Gases, Chemicals and Hazardous Materials


In this thirteenth and final installment is concluded the discussion of chemicals and hazardous materials more commonly encountered in fire fighting. Methods of shipping and handling and their action under exposure to fire are given for most of the materials.


Oil is a liquid of vegetable, animal or mineral origin, lighter than, but easily mixable with water, but soluble in sulphuric ether.

There are three types of oils encountered: vegetable oils, animal oils and mineral oils.

The fundamental difference between vegetable and animal oils and the petroleum and coal tar oils is found in the fact that the vegetable and animal oils consist primarily of carbon, hydrogen and oxygen, while the petroleum (mineral) and coal tar oils do not contain oxygen, but are primarily compounds of carbon and hydrogen.

As a general rule, none of the vegetable and animal commercial oils are volatile or even inflammable; in fact, the normal flash point of these oils centers around 500 F., but nearly all can cause spontaneous ignition. On the other hand, a number of petroleum and coal tar oils are very volatile and the majority are easily ignited, hut none will induce spontaneous ignition.

With vegetable oils there is usually danger of spontaneous ignition, due to heating caused by fermentation or other chemical processes. This same danger is present in a minor degree with animal oils.

The most striking difference between vegetable and animal oils and mineral oil manufacture is this: With mineral oils we start with oil and have no bulky hazardous by-products, but the production of vegetable and animal oil commences with seed, copra, nuts, offal, etc., and after the oil is expelled or extracted we still have to dispose of linters, hulls, presscake, tankage, etc. The alarming thing about all of these by-products is the fact that they heat and ignite spontaneously.

Among vegetable oils and fats commonly encountered are: linseed oil, pcrilla oil. tung oil, soy bean oil, cotton seed oil, corn oil, rape oil, mustard oil, olive oil. peanut oil, castor oil. cocoanut oil, palm oil. and palm kernel oil. There are a great number of other vegetable oils of lesser note.

Animal Oils: Among the animal oils and fats commonly found may be listed the following: tallow, oleo oil, lard oil, bone oil, neatsfoot oil, red oil and fish oils.

As animal and vegetable oils do not constitute a severe hazard, either from the standpoint of life or fighting fire, they will not be treated in detail.

Mineral Oils: On the other hand, as mineral oils of petroleum base represent sever hazards, they will be covered with some detail.

Cymogene—principally butane, gravity about 100° Baume (Be). An anaesthetic and refrigerant. Boiling point 32° F. It is a gas at ordinary temperatures.

Rhigolene—principally petane—gravity about 95° Be. Boiling point about 64°

Canadol—Light petroleum ether, about 76° Be gravity.

Benzine—principally heptane, boiling point, 113° to 140° F., gravity’ about 85° Be. Not to be confused w-ith the aromatic hydrocarbon benzene, or benzol.

Gasoline—Gravity from 60° Be to 74° Be. Gravity is not dependable in determining quality of gasoline, end point or final boiling point being far more reliable. This should never exceed 350° F. Flash test—1° F.

Gasoline throws off vapors at ordinary room temperatures, the vapors traveling with great rapidity. The hydrocarbons pentane to octane have a vapor pressure varying from 55 to 0.7. The specific gravity of these gases varies from 2.496 to 3.592; therefore, the gases being much heavier than air, will not rise to a greater elevation than three feet if not confined. Explosive air and gas mixtures may vary from 1.5 to 6 per cent by volume, of gas.

Naphtha: A term now loosely applied to all lighter products distilling below 260° F.; it is essentially the heavier fraction obtained from redistillation of crude benzine. Boiling point from 203° F. to 248° F., and gravity from 56° Be. to 49° Be.

Kerosene: (Also known as waterwhite. burning oil, lamp oil or illuminating oil) has a boiling point of 450° F.; flash test, 110° F.; 150° F. fire test and 47° Be. gravity. Sometimes manufactured with gravity lighter and 110° F. fire test, and for railroad purposes with heavier gravity and 300° F. fire test.

Gas oil: Consists principally of olefines, produced in large quantities by Kansas refiners, gravity about 34° Be. to 36° Be. Used in manufacture of socalled gas and as fuel for Diesel engines.

Neutral oils: Consisting of oils carrying paraffin obtained from distillation of paraffin base petroleum. Gravity 32° Be. to 36° Be. and flash point 290° F. to 350° F. Also known as wax distillate. After removal of wax. the pressed distillate is fractioned, the lighter fractions being non-viscous neutral oil, the heavier fractions viscous neutral oils, and from all of w’hich are produced various grades of lubricating oils. Spindle oils come within this class, although they differ from paraffin oils in that the flash test and fire test is higher at a given Be. gravity. Automobile lubricating oils usually have a flash test of from 390° F. to 450° F.

Cylinder oil: Requiring proper vis-

cosity at steam cylinder temperature, will have a flash test of 540° F. to 630° F., equivalent to fire test of 600° F. to 710° F.

Fuel oil: Produced in many different gravities and flash points. Its viscosity sometimes makes pre-heating necessary. Flashpoints vary from 125° F. to 150° F.

Paraffin wax: Manufactured in varying grades, melting point ranging from 110° F. to 130° F„ gravity 27° Be.

Road oil: A rather broad designation of any’ residuum of asphaltic base, grading from liquid road binder to solid asphalt paving. Gravity varies from 34° Be. to 16° Be, with flash point varying from 250° F. to 410° F. and fire test ranging from 300° F. to 540° F.

Coke: Final residuum of distillation to dryness. Extensively’ used in the manufacture of carbons for electrical devices.

Vaseline: Sometimes termed petroleum, consisting of hydrocarbons of the paraffin series and some olefines. Gravity about 35° Be. at 100° F. Produced from residue remaining in stills after distillation of lighter reactions, including wax distillate, the residue being reduced, filtered and steamed rod wax added. Sometimes crude oil is first chilled, forming a heavier sediment, which is firestilled and reduced to a melting point of 100° F. to 120° F„ and filtered.

Coal tar oils: Coal tar is derived from by-products coke ovens and from gas works. It is a thick, very dark brown, oily liquid with a flash point of about 60° F. below zero. Its chemical makeup is exceedingly complex and but poorly understood.

The fire hazard and flash hazard of coal tar should be classed with crude petroleum. It flashes readily and burns freely with the emission of tremendous amounts of pitch black smoke.

A Pungent Rubber Bonfire Thousands of second-hand automobile tires going up in smoke in an old tire yard. Firemen with smarting eyes and smoke filled lungs fought this fire for hours.

Upon distilling the tar. there is obtained. according to its quality, 2 to 8 per cent of light oil, 8 to 10 per cent of middle or carbolic oil. 8 to 10 per cent of heavy or creosote oil. 16 to 20 per cent of anthracene oil, and the residue. somewhat over 55 per cent, is pitch and coke. From light oil is distilled the crude benzol, a mixture of benzol, toluol, zylol, and solvent naphtha, an excellent motor fuel.

Benzol—is used as a fuel for automobiles. but in winter it has to be mixed with 15% to 40% of gasoline, as otherwise it freezes at 32° F.

Benzol flashes at 16° below zero Fahr. In other words, it still flashes when frozen solid.

Toluol—which flashes at 46° F., is used as a solvent, but is primarily used in synthetic dye industry and for the manufacture of military explosives.

Xylol—is used in the synthetic dye and for the making of explosives. Its flash point is 80° F.

Solvent naptha—as its name indicates, is an excellent solvent and is used for that reason quite extensively in the paint, varnish and enamel industries. Its flash point is 60° F.

Coal-tar oil summary: Summarizing, we may say that all the coal tar oils burn freely, and that light oil, benzol, toluol, xylol, pyridine and solvent naphtha are practically of fire and explosion hazard equal to gasoline.

None of the coal tar oils will, however, induce spontaneous combustion.

Carbon bisulphide (carbon disulphide):

Carbon-bisulphide is very poisonous. Commercial or impure carbon-bisulphide readily attacks iron, rendering the apparatus unsafe. Carbon-bisulphide is more to be feared by fire departments than any other liquid in common use. It evaporates more readily than gasoline. The vapor is much heavier than air, and travels along the ground much faster than the vapor of gasoline. The vapor is much harder to dislodge or disseminate than that of gasoline, and, mixed with air, it has the widest known range of explosibility, exceeding even that of acetylene gas. Carbon-bisulphide, being heavier than water, can be handled under water; for instance, this is done regularly in rubber extracting.

Carbon-bisulphide boils at 117 degree Fahr. and ignites spontaneously at 212 degrees Fahr. In other words, the heat of a steam pipe is sufficient to ignite it. The normal flash point is 22 degree Fahr.

Carbon-bisulphide vapor exhausted from a steam-heated apparatus ignites spontaneously when striking the atmosphere.

Sulphuric ether: Sulphuric ether is only used as a solvent in limited quantities in extracting pharmaceutical matter. It evaporates with exceeding rapidity, forms explosive mixtures with air, and is, as everyone knows, not to be inhaled with impunity. Its flash point is 49 degree Fahr., and it breaks into flame spontaneously at 356 degree Fahr. However, as it is very expensive and used only when absolutely unavoidable, we shall generally find that very little is allowed to escape into the air, and that the supervision is usually of a high standard.

Chloroform: Chloroform evaporates very rapidly and cannot be inhaled without the most serious consequences. It forms explosive mixtures with air. It is decomposed by light, giving off the extrcmely poisonous gas phosgene. Like ether, it is only used on a limited scale, generally under high-grade technical conditions.

Gases, Chemicals and Hazardous Materials


Gases, Chemicals and Hazardous Materials

Part XII

In this twelfth installment is continued the discussion of chemicals and hazardous materials more commonly encountered in firefighting. Methods of shipping and handling and their action under exposure to fire are given for most of the materials.

Sodium nitrate (also caled chili saltpetre, chili nitre, soda nitre): This is a white crystalline substance, containing nearly half its weight of oxygen which it readily gives up when heated with oxidizable substances. It does not burn itself, but, being an oxygen carrier, it assists in the combustion of other material. When melted it will set on fire any combustible material with which it comes in contact. It is generally shipped in burlap bags containing about 200 pounds each, but it may also be found in tins and glass bottles. It is used in the manufacture of nitric acid, fertilizers, explosives, etc.

As it is an oxidizing material, it will increase the intensity of a fire. Bags or barrels may become impregnated with it, in which condition they are readily ignitable. In contact with organic or readily oxidizable (combustible) substances it will cause violent combustion on ignition.

Most fires involving sodium nitrate can safely be deadened with water in the early stages; at such times they should be flooded with water. When large quantities are involved in the fire, the sodium nitrate may fuse or melt, in which condition application of water would result in extensive scattering of the molten material, and, therefore, care should be taken in applying water to the

Sodium perchlorate: Usually shipped a dry place.

material after the fire has been burning in iron canisters, and glass bottles. It is an oxidizing material, and classes with for some time. It should be stored in hazard. It is dangerous to life under potassium chlorate in respect to fire storage.

Sodium sulphide: A yellow, lumpy or granular substance used in dye stuffs manufacture. A number of fires have occurred in this material, apparently from spontaneous heating of freshly made, freshly dried, or freshly ground substance, which is unstable, due to tendency to oxidize. It is moderately flammable and classes with potassium sulphide.

Strontium nitrate: A white powder largely used in marine signals, railroad flares, etc., for producing red flame. It is an oxygen carrier. It is similar to strontium chlorate, but slightly less in degree of hazard. It is usually shipped in barrels and boxes. It should be safeguarded against mechanical injury in storage and kept away from other materials.

Sulphur (brimstone, sulfur): A pale yellow solid or powder. It may be ignited at about 482° Fahr., burning with a relatively cool flame. It is largely used in the manufacture of wood pulp, in rubber compounding and in sulphuric acid manufacture. Large quantities are used in agricultural insecticide as bordeaux mixture and lime sulphur. It is used in bleaching and in various industrial, chemical and medicinal applications. It is a constituent of black powder. Alone, it is lightly hazardous, but on account of the suffocating sulphur dioxide gas formed when it burns, it is dangerous in the event of fire. Sulphur dioxide, however, does not support combustion, and its smothering effect may be used to extinguish chimney fires. In the presence of carbon, lampblack, and oils it may promote spontaneous combustion, while with chlorates and other oxygen carriers, it may be explosive. As noted before, the fumes are suffocating and they thus represent a life hazard, when the sulphur is involved in a fire.

Sulphuric acid: There are two main classes of sulphuric acid. (1) Ordinary or non-fuming sulphuric acid, and (2) fuming sulphuric acid.

The first mentioned will char wood and other carbonaceous materials but it does not corrode iron to any extent. The second mentioned, the fuming sulphuric acid, is very active, attacking certain metals. It is used in almost every industry and is essential to the manufacture of explosives, dyes, fertilizers. Heat, generated by mixing water with the acid, may cause fire or explosion. It may cause ignition by contact with combustible materials. Sulphuric acid is usually shipped in carboys, iron drums, glass bottles and tank ears. The fumes as well as the liquid are highly corrosive and therefore dangerous to life, when met with under fire conditions. In storage, containers should be safeguarded against mechanical injury, isolated from saltpetre, metallic powders, carbides, fulminates, chlorates and combustible materials.

Uranium nitrate: A yellowish crystalline salt, used in photography, medicine, and as a glaze. It is shipped in glass bottles and boxes. It is an oxidizing material and oxygen carrier and supports combustion. It is classed with sodium nitrate. It should be stored in a dry place, prevented from coming in contact with organic or combustible materials.

Zinc chlorate: A white, crystalline substance used as an oxidizing agent. It is shipped in iron drums or glass bottles. The material is dangerous with organic material, sulphuric acid, etc., being an oxygen carrier. When in contact with organic material it explodes by slight friction, percussion or shock. It classes with potassium chlorate. It represents a severe life hazard under fire conditions. It should be safeguarded against mechanical injury in storage.

(To be continued)

A Hot Fire Which Caused One Death The toll of this fire in a motion picture film laboratory was one dead, eigtht injured and $6,000,000 worth of film destroyed.