Hazards of Common Materials

This chapter is not concerned with the hazards of obviously dangerous materials, such as highly flammable liquids and gases, or toxic materials. Rather, the focus is on accidents involving those common but dangerous substances air, water, nitrogen, and heavy oils. 

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Undoubtedly, fire hazard is partially associated with the toxicity of the smoke itself. The smoke of a variety of common materials, as measured e.g. by the NBS cup furnace toxicity test [10], has recently been compared with the intrinsic toxic potency of other poisons and of toxic gases, as well as with toxicity categories [11]. It has been shown that toxicity is a relatively minor factor because there is very little difference between the intrinsic toxic potency of the smoke of the majority of common materials, with very few exceptions. 

Rcsearch sponsored by the Brominated Flame Retardants Industry Panel regarding the use of brominated flame retardants shows that there is no evidence that the use of decabromodiphenyl oxide leads to any unusual risk. In addition, a study by the National Bureau of Standards (now National Institute of Science and Technology) showed that the use of flame retardants signilicanily decreased the hazards associated with burning of common materials under realistic fire conditions. Work in Japan confirms this finding. 

Regular ambient air has an oxygen level of 20.8 vol.%. The table shows that lowering the levels by only a few percentage points can effectively reduce the fire hazard of a number of common materials. 

Since 1981, we have been developing and testing in the laboratory, methods for the onsite disposal of small quantities of a variety of hazardous chemicals (Armour, 1996a). We have been able to apply many of the methods to disposing of the residues from the cleanup of spills of these chemicals. The application of several of the methods to spills of commonly used hazardous chemicals is described in subsequent paragraphs. The quantity of spilled material to which the disposal procedures are applicable varies with the hazard of the material spilled. In general, these procedures can be applied to the quantities of chemicals normally handled and transported in laboratories. As a guide, the disposal procedures are applicable to spills of up to about 4 L of liquid. 

The characteristics that are measured in a fire test are indicative of the performance of the material under the conditions of the test and are therefore referred to as fire-test-response characteristics. They may or may not be indicative of the hazard of a material under actual fire conditions. The most common fire-test-response characteristics that are measured in fire tests are the ease of ignition, flame spread, heat release, smoke generation and toxic potency of smoke (20,25). 

P-24 Guide to the Preparation of Material Safety Data Sheets. If you ship, sell, or handle hazardous materials, this standard should be a part of your library. OSHA, WHMIS and other authorities require the preparation and distribution of MSDSs (material data safety sheets) which describe the hazards of a material and provide information on how the material can be safely handled, used and stored. This document has been developed to provide guidance for preparing material safety data sheets for compressed gases. It also provides actual MSDSs for several commonly used gases (103 pages). 

Two of the most common labeling systems are the National Fire Protection Association (NFPA 704-B see figure 5.2) and the Hazardous Materials Identification System (HMIS). These systems provide a number key to indicate the relative hazard of the material in the areas of health, flammability, and reactivity. The number system is from 0 for nonhazards to 4 for extreme hazards. 

The procedure begins by using a material factor that is a function only of the physical properties of the chemical in use. The more hazardous the material, the higher the material factor. A table containing factors for common materials is provided with the Index. Additionally, a procedure is detailed for determining the material factor for unlisted materials. 

Health and Safety Factors. The strontium ion has a low order of toxicity, and strontium compounds are remarkably free of toxic hazards. Chemically, strontium is similar to calcium, and strontium salts, like calcium salts, are not easily absorbed by the intestinal tract. Strontium carbonate has no commonly recognized hazardous properties. Strontium nitrate is regulated as an oxidizer that promotes rapid burning of combustible materials, and it should not be stored in areas of potential fire hazards. 

The membrane is usually made from one of several materials. Woven polyester or cotton, the most commonly used and least expensive material, is adequate for temperatures up to 150°C. Siatered plastic is used where a low cost, washable surface is desired. This material is temperature limited by the polymer material to about 60°C and the flow of some powders may cause a static charge build-up on the membrane that could be hazardous ia some operatioas. Wovea fiberglass fabric or porous ceramic block is used for temperatures up to about 425°C. Siatered stainless steel powder or bonded stainless mesh is used for corrosion resistance, and for temperatures up to 530 to 650°C. Additional information can be found ia the Hterature (38,39). 

To reduce costs of the more expensive platiag solutioas and decrease the amount of hazardous or regulated material ia a waste stream, recovery and reuse of the drag-out is a common practice. This is done by closing off the water flow to the first tinse tank foHowiag the process tank, and periodicaHy... 

Chemical Reactivity - Reactivity with Water. Dissolves and forms a weak solution if nitric acid. The reaction is not hazardous Reactivity with Common Materials May corrode metals in presence of moisture Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

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