Information sources flammability

An important point here is to not let the principal hazard mask other important hazardous properties of a chemical. It is important to review other information sources about the chemical to be sure that you understand all of the potential hazards of the chemicals that you are using. Eor example, see the SDS in Appendix A under Section 2 about the hazards of chemicals. Eor this chemical, acetonitrile, a principal hazard is that it is highly flammable but it can also cause serious eye irritation. It is also possible that some hazardous properties of chemicals have not yet been recognized, studied, or documented, so you must treat all chemicals with care, minimizing your exposure to the greatest extent possible. This is easy to do in a well-equipped laboratory so you will be able to usemost chemicals very safely. This will be discussed more in Chapter 7. 

The methods described in this chapter are meant for practical application background information is given in Chapter 4. If a quantity of fuel is accidentally released, it will mix with air, and a flammable vapor cloud may result. If the flammable vapor meets an ignition source, it will be consumed by a combustion process which, under certain conditions, may develop explosive intensity and blast. 

Professor Martel s book addresses specifically some of the more technical eispects of the risk assessment process, mainly in the areas of hazard identification, and of the consequence/effect analysis elements, of the overall analysis whilst where appropriate setting these aspects in the wider context. The book brings together a substantial corpus of information, drawn from a number of sources, about the toxic, flammable and explosive properties and effect (ie harm) characteristics of a wide range of chemical substances likely to be found in industry eind in the laboratory, and also addresses a spectrum of dangerous reactions of, or between, such substances which may be encountered. This approach follows the classical methodology and procedures of hazard identification, analysing material properties eind... 

Accident statistics on the equipment involved in large losses give somewhat contradictory information (see Table 20). According to Mahoney (1992) the most common process items as primary accident cause are reactors. The next in the list are process drums whereas heaters are one of the safest. This contrasts with Instone s (1989) data, where heaters and boilers were the most common process items in the accidents, whereas reactors and process drums were quite uncommonly involved. This difference may be partly because Mahoney has analyzed the primary causes of large losses, whereas Instone has listed the involvement of equipment in losses. Since furnaces are sources of ignition for flammable leaks from other equipment, furnaces are not necessarily listed as primary causes even they are probably involved as secondary causes in many losses. Therefore the inclusion of both reactors and furnaces in the list of most unsafe equipment is well justified. 

While solid fires generally do not have the same impact as flammable material fires in process units, the hazards from solids are important in several respects. Class A materials may be the source of ignition for hazards having a greater combustible loading or posing a greater threat in terms of impact and Class A or D solids may pose a threat due to inherent reactivity or use in a process. For more information on solid fires, refer to SFPE Handbook (Beyer, 2002). Radiant heat from solid fires can be calculated similarly to that of pool fires. 

Many apparently mysterious fires and explosions have eventually been traced to static. In spite of the large amount of information about static electricity, it remains a complex phenomenon not often understood and appreciated. Static electricity is a potential source of ignition whenever there is a flammable mixture of gas or dust. 

From these three sources of information the peak value of the rate of pressure increase due to deflagration of mixtures of oxidizers and flammable substances is given at the maximum heat of reaction, and a similarity is found between the open systems in the IMO combustion rate test and the partially enclosed systems in the TNO deflagration test. 

Detailed information about material flammability derived from macroscopic combustion parameters is given by Petrella who considered the effect of an external heat source on the mass rate of polymer combustion. From the energy conservation law it follows ... 

A few hydrocarbon derivatives from the alkyl-halide family are 2.2 nonflammable compressed gases. This illustrates the wide range of hazards of the alkyl halides as a group. Some are flammable, some are toxic, and some are nonflammable and nontoxic. They can still act as asphyxiants and displace the oxygen in the air. It is important to remember that the primary hazard of the alkyl halides is toxicity. Some of them are also flammable therefore, all must be assumed to be toxic and flammable until the individual chemical is researched and the actual hazards are determined. It is interesting to note that while the DOT lists tetrafluoromethane as a nonflammable, nonpoisonous gas, the Condensed Chemical Dictionary lists the compound as toxic by inhalation. The NIOSH Pocket Guide to Chemical Hazards does not list the compound. The best source of information about this compound and others may be the MSDS (material safety data sheet). Examples of nonflammable Class 2.2 alkyl halides are tetrafluoromethane and trifluoromethane. 

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