Fires, accidental materials

Chlorinated and brominated materials are burned or thermally treated in a variety of combustion sources including hazardous and municipal waste incinerators, industrial processes, backyard trash burning, and accidental fires. Chlorinated materials are used in a wide range of applications and brominated compounds are fire retardants used in many devices including electronic circuits. Although there has been some research on the reactions of CHCs and BHCs in the past 20 years, too little is known about their reactions considering the magnitude of the environmental impact. Elementary reaction studies of gas-phase reactions of Cj and C2, CHCs, and BHCs are needed to understand their most fundamental reaction properties. Reactions of the chlorinated and brominated benzenes and phenols are important intermediate steps in the formation of PCDD/F. Recent kinetic models indicate that the gas-phase reactions may be quite important and elementary gas-phase reaction studies have been overlooked by researchers. 

One effective storage method is to keep the material covered with water in the containers and in turn use oil on the water to keep it from evaporating. If a fire accidentally starts in zirconium, do not attempt to put it out with water or ordinary fire extinguishers. Use dry sand salt, or commercially available Metal-X power (Ansul Manufacturing, Marinette, Wisconsin). Large quantities of water can be used to control and extinguish fires in other flammables in the vicinity of a zirconium fire. 

Hypergolic A hypergolic mixture ignites upon contact of the components without any external source of ignition (heat or flame). The only field, in which this is a desirable event, is in rocket fuel research. Accidental mixing of incompatible materials can lead to a fire or explosion. Here is one example provided by the staff at ILPI of what can happen, when incompatibles are mixed. Always read the labels on your bottles (don t assume a chemical s identity by the shape, size, or color of the bottle), and know what materials are incompatible with the chemicals that you are using. 

Tlie remainder of tliis cliapter provides information on relative physical properties of materials (flash points, upper and lower explosive limits, tlireshold limit values, etc.) and metliods to calculate tlie conditions tliat approach or are conducive to liazardous levels. Fire liazards in industrial plants are covered in Sections 7.2 and 7.3, and Sections 7.4 and 7.5 focus on accidental explosions. Sections 7.6 and 7.7 address toxic emissions and liazardous spills respectively. tliese latter types of accident frequently result in fires and explosions tliey can cause deatlis, serious injuries and financial losses. 

The likelihood (probability) of an accidental release based on tlie history of current conditions and controls at tlie facility, consideration of any unusual environmental conditions (e.g., areas in flood plains), or tlie possibility of simultaneous emergency incidents (e.g., flooding or fire liazards resulting in tlie release of hazardous materials). 

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

The influence of metal species like copper has been investigated on the product pattern and yield of PBDD/F (Fig. 7) (ref. 11). This study is relevant to accidental fires of polymeric materials of electronic devices which are associated with various metals like copper. As a result of the presence of the metal species substantial amounts of both PBDF and PBDD are formed. 

Other accidents could have introduced early cultures to the hallucinatory effects. While harvesting the plant for seeds (for oil) or fiber, accidental fires could have produced a resinous smoke, which was then inhaled. The smoke would have also appealed to the magicoreligious practices of native shamans (30). The smoke itself is inherently evocative of visions and mystery—a natural medium for shamanism It contained a property that could induce a form of trance it was readily consumed by the cleansing power of fire its smoke rose to the abode of the gods and it allowed dreams to be materialized. 

Hazardous substances present in the process are identified on the basis of their flammability, explosiveness and toxicity. The flammability of gases and vapours of flammable liquids is a great concern in the process industries. The result of an ignition can be a fire or an explosion or both. Accidental fires and explosions of flammable mixtures with air often follow the escape of combustible materials or inlet of air into process equipment. 

In ideal combustion 0.45 kgs (1 lb.) of air combines with 1.8 kgs (4 lbs.) of oxygen to produce 1.2 kgs (2.75 lbs.) of carbon dioxide and 1.02 kgs (2.25 lbs.) of water vapor. Carbon monoxide, carbon dioxide, nitrogen and water vapor are the typical exhaust gases of ordinary combustion processes. If other materials are present they will also contribute to the exhaust gases forming other compounds, which in some cases can be highly toxic. Imperfect combustion will occur during accidental fires and explosion incidents. This mainly due to turbulence, lack of adequate oxidizer supplies and other factors that produce free carbon (i.e., smoke) particles, carbon monoxide, etc. 

Accidental incidents involving new types of emergencies began to surface in the 1940s. They were linked with the behavior of certain chemical products collectively called hazardous chemicals (or hazardous materials) whenever they are misused or involved in unintended mishaps and fires. 

We pointed out earlier that most emergency plans address fire, medical emergencies, and the accidental release or spills of hazardous materials. Note that the development of emergency response plans should also factor in other possible emergencies— natural disasters, floods, explosions, and/or weather-related events that could occur and certainly will occur. Now, emergency response to terrorist activity or threats must also be added to the list. 

Materials awaiting destruction should be stored at a distance of not less than 500 ft, preferably in small piles located about 100 ft apart. This is to prevent accidental ignition or explosion from fragments, burning embers or grass fires... 

The handbook contains information needed to help personnel make the proper response to handling chemicals and in particular during an emergency situation as such, this handbook could be carried to the actual scene of a hazardous materials incident. In the latter case, it is intended for use by personnel and others who may be the first to arrive at the site of an accidental discharge or fire and who need readily available and easily understood information about the hazardous properties of the chemical involved. The information provided can assist in determining the proper actions that should be taken immediately to safeguard life and property and to prevent contamination of the environment. 

Personal Protective Equipment — The items are those recommended by (a) manufacturers, either in technical bulletins or in Material Safety Data Sheets, (b) the Manufacturing Chemists Association, or (c) the National Safety Council, for use by personnel while responding to fire or accidental discharge of the chemical. They are intended to protect the lungs, eyes, and skin. 

Most combustible liquids do not present a vapor problem if accidentally released into the atmosphere. The probability of a fire, therefore, is considerably less than it would be if the spill was of a flammable material. If, however, the combustible liquid is at a temperature higher than its flashpoint, then it can be expected to behave in the identical manner a flammable liquid. One major difference between the two in a fire situation is that the potential exists for cooling the combustible liquid below its flash point by the proper application of water (generally applied in the form of water spray). In the event the liquid is burning, and if the fire forces are successful in achieving the required reduction in liquid temperature, then vapor production will cease and the fire will be extinguished because of a lack of vapor fuel. Unless this reduction in liquid temperature can be brought about, the fire will necessitate the same control considerations a low-flash liquid fire would. 

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