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iuLv:lullVt t�s�UL.Ltit. ��-� 65.1 "AJOR USES A►yA COMPOSITION 65.1.1 Major Uses Gasoline is a volatile mixture of flammable liquid hydrocarbons derived chiefly from crude petroleum and used principally as a fuel for internal combustion engines. Consumption of gasoline by motor vehicles in this country was approximately 103 billion gallons in 1983, down from a peak consumption of 116 billion gallons in 1978 (1409) . 65.1.2 Composition Automotive gasoline is composed of several hundred hydrocarbons in the range of CI to C11 and with boiling points from approximately 309C =F to 210'C. General composition expressed as percent weight by compound category has been reported to be: 494 to 624 aliphatic hydrocarbons r4 (28-364 branched alkanes, 15-17% n-alkanes. and 3.53 cycloalkanes) , 14 11-1 to 114 olefinic hydrocarbons, 204 to 494 benzenes and alkylbenzenes and up to to 1% naphthalenes (2320,1843,1849) . As noted with JP-4 (Chapter 64) , the concentrations of specific hydrocarbons in different gasoline samples are highly variable and are expected to become even more variable as the availability of leaded gasoline is reduced. For example, as reforming severity was adjusted ' to achieve the required increase in octane levels of unleaded gasoline pools. average aromatic content increased from 224 in 1970 to 274 in 1980 and 1984: as leaded gasoline is phased out, the aromatic content will increase further to 354. Olefin content also increased from 84 in r 1980 to 114 in 1984 (2319) . The individual components of gasoline have been characterized by several authors (2320,2311,1843) . Table 65-1 summarizes the available P� hydrocarbon composition data for various gasolines. As discussed in Chapter 64 (JP-4) , petroleum-derived distillates may also contain many non-hydrocarbon components. These may become major concerns in heavy distillates and residues but are much less important in Light distillates such as automotive gasoline where only trace quantities of sulfur- , nitrogen- , and oxygen-containing compounds have been detected. Large variations in trace element concentrations were reported but no quantitative data were available (1843) . Automotive gasoline also contains a number of additives used as octane improvers. antioxidants, metal deaccivators, corrosions or icing =r inhibitors, detergents or demulsifiers. A list of some of the chemical classes and specific chemicals that may be used for these purposes is provided in Table 65-2. F r �x 6/87 _A_