Key Names Flash Warning About Chemicals on Trucks
The Volunteers Corner
Chemicals create a major problem in truck fires because they raise a question that demands an immediate answer: “What can I use to extinguish this fire?”
The answer is not always a simple one—and sometimes nobody may have it. I recently read a newspaper story of a blast at a chemical plant that killed two men while a tank truck was being unloaded. The paper reported that until the blast, chemists at the plant believed that there was no danger in the operation.
In volunteer fire department areas, the number of plants handling dangerous chemicals is usually limited. Therefore, it is not an extensive project to obtain information from a handful of firms about the chemicals they use and how to handle a fire involving these chemicals.
But a highway incident is a different problem. An individual department has no idea of the variety of chemicals being trucked over the roads in its district except that the variety can be expected to be extensive and surprising.
Bills of lading: Despite the fact that fire officers are not expected to be graduate chemists, they are expected to come up with an answer when a truck is burning. And the first thing they must determine is what is on the truck. Tankers are often clearly marked, but the marking should immediately be verified by questioning the driver. Mixed dry cargoes provide more of a problem because the driver may have no personal knowledge of every item he is carrying. But he is required to carry bills of lading listing everything in his load, and the first-due officer should ask for the bills of lading. If the driver has been injured in a crash-fire, the officer may have to search for the bills of lading in the truck cab.
Many chemicals are shipped as compounds. No fireman can hope to recognize everything in the untold number of compounds available today. But certain key words or syllables can be recognized as warning signals.
There are oxidizing chemicals known as inorganic nitrates (sodium, potassium and ammonium nitrate are common ones) which increase the intensity of a fire in other materials or make ignition easier. And the three cited all have an explosion hazard. So nitrate should be recognized as a danger signal.
Nitrites are not the same as nitrates, but ammonium nitrite and some other nitrites are explosive. Although nitrites are less active than nitrates as oxidizing agents, they can be handled alike as far as fire fighting is concerned.
More oxidizing agents: The inorganic peroxides (barium, hydrogen, potassium, sodium, strontium) also are oxidizing agents. The last three react vigorously with water, releasing both heat and oxygen.
The chlorates (potassium and sodium) can form explosive mixtures. The perchlorates, with one or more oxygen atoms, have similar characteristics but are regarded as somewhat more stable than the chlorates.
The sulfides (antimony pentasulfide, phosphorous pentasulfide, phosphorous sesquisulfide, potassium sulfide, sodium sulfide) are among the combustible chemicals.
The cyanides (hydrogen, potassium and sodium) are among the unstable chemicals. Hydrogen cyanide may polymerize and go to an explosive reaction. Potassium and sodium cyanide, when in contact with acids or moisture, release poisonous, flammable cyanide gas.
The organic peroxides (benzoyl, ether), widely used in the plastics industry, also are unstable and combustible.
Explosive reaction possible: Among the water-reactive chemicals are the carbides (sodium, potassium) which may react explosively with water.
The metal hydrides (sodium, lithium, lithium aluminum) also react with water and form highly flammable hydrogen gas.
The inorganic acids (sulfuric, nitric, hydrochloric, hydrofluoric, perchloric) are corrosive chemicals injurious to living tissue. Leakage and mixture with other chemicals or combustible material may result in a fire or explosion.
We have not tried to tell you how to handle these chemicals in a truck fire. We would need to write a book to do that. Our only attempt here is to point out some danger signals.
Get answer by radio: Your best bet is to have a copy of NFPA No. 49, “Hazardous Chemicals Data,” at your radio base station. At the highway incident, the officer in charge can radio a request for information about the chemical (or chemicals) involved. The base station operator can look up the recommendations for fire fighting and the characteristics of the chemical listed in NFPA 49 and transmit the information. He is in a better position than the man at the scene to do this because he has plenty of light to read and is not disturbed by the activity and excitement on the highway.
The Manufacturing Chemists’ Association publishes a “Chem-Card Manual” and individual Chem-Cards covering 85 chemicals. An appropriate Chem-Card can be carried on the truck. The information covers fire and exposure hazards and tells what to do in case of a spill or leak, a fire, or exposure of personnel.