gasoline(redirected from unleaded gasoline)
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petrol,light, volatile mixture of hydrocarbons for use in the internal-combustion engineinternal-combustion engine,
one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power.
..... Click the link for more information. and as an organic solvent, obtained primarily by fractional distillation and "cracking" of petroleum, but also obtained from natural gas, by destructive distillation of oil shales and coal, and by a process that converts methanol to gasoline using zeolite as a catalyst. Gasoline intended for use in engines is rated by octane numberoctane number,
figure of merit representing the resistance of gasoline to premature detonation when exposed to heat and pressure in the combustion chamber of an internal-combustion engine.
..... Click the link for more information. , an index of quality that reflects the ability of the fuel to resist detonation and burn evenly when subjected to high pressures and temperatures inside an engine. Premature detonation produces "knocking" and "pinging"; it wastes fuel and may cause engine damage. The addition of tetramethyl lead and tetraethyl lead to raise the octane number is no longer permitted in the United States because it leads to dangerous emissions containing lead. New formulations of gasoline designed to raise the octane number contain increasing amounts of aromatics and oxygen-containing compounds (oxygenates), such as alcohols, methyl tertiary butyl ether (MTBE), and methylcyclopentadienyl manganese tricarbonyl (MMT). Automobilesautomobile,
self-propelled vehicle used for travel on land. The term is commonly applied to a four-wheeled vehicle designed to carry two to six passengers and a limited amount of cargo, as contrasted with a truck, which is designed primarily for the transportation of goods and
..... Click the link for more information. are now equipped with catalytic converters that oxidize unreacted gasoline; the cars are designed to run on newly formulated gasolines as well as on gasoholgasohol,
a gasoline extender made from a mixture of gasoline (90%) and ethanol (10%; often obtained by fermenting agricultural crops or crop wastes) or gasoline (97%) and methanol, or wood alcohol (3%).
..... Click the link for more information. , which contains 10% ethanol or 3% methanol. In addition, since 1998 a number of American automobiles have been equipped to enable them to run on either gasoline or E85, a mixture of 85% ethanol and 15% gasoline. Some racing cars use pure methanolmethanol,
or wood alcohol,
CH3OH, a colorless, flammable liquid that is miscible with water in all proportions. Methanol is a monohydric alcohol. It melts at −97.8°C; and boils at 67°C;.
..... Click the link for more information. as fuel.
There are five blends of gasoline marketed in the United States. Conventional gasoline, the most widely available, is sold where air quality is satisfactory; since 1992, it has been formulated to evaporate more slowly in hot weather so as to reduce smog, and it now contains detergent additives to reduce engine deposits. Winter oxygenated gasoline, introduced in 1992, is formulated as conventional gasoline with oxygen-rich chemicals added, such as MTBE or ethanol. The oxygen promotes cleaner burning, reducing carbon monoxide, and is generally sold from November to March because cold engines operate less efficiently and produce more carbon monoxide. Reformulated gasoline (RFG), introduced in Jan., 1995, is mandated in areas where toxins in the air are a constant problem; it contains oxygen-rich chemicals in lesser concentrations than the winter oxygenated gasoline and is formulated to reduce certain toxic chemicals found in conventional and winter oxygenated fuels. Oxygenated reformulated gasoline is a wintertime fuel exclusive to the New York City area, where heavy carbon monoxide pollution occurs. California reformulated gasoline, introduced in 1996, has a different formulation and burns cleaner than regular reformulated gasoline. Because MTBE has been implicated as a pollutant, particularly of groundwater, its use is being curtailed. In 1999, California ruled that the MTBE in California reformulated gas must be phased out by Dec. 31, 2002.
See Society of Automotive Engineers Incorporated, ed., Gasoline and Diesel Fuel: Performance and Additives (1997).
a mixture of hydrocarbons of various structures; a colorless liquid that boils in the range from 30° to 205° C. Its freezing temperature is below -60° C, its flash point is below 0°C, and its density is 700–780 kg/m3(0.70–0.78 g/cm3). Explosive mixtures are formed at concentrations of 74–123 g of gasoline vapors per cu m of air.
The primary sources of gasoline are distillation and catalytic refining of oil; small amounts are obtained by the conversion of mineral coal and bituminous shales, as well as from natural and by-product gases. Gasoline is used primarily as fuel for internal-combustion engines with spark ignition (with carburetors or with direct injection); approximately 10 percent of gasoline is used as solvents or cleaning fluids and for other purposes. The gasolines that are used as fuel are divided into automotive and aviation types (see Tables 1 and 2).
Automotive gasolines are divided into summer types (for use from April through September in all regions except the northern and northeastern) and winter types (for the northern and northeastern regions; in the remaining regions from October through March). Winter gasolines contain a larger quantity of low-boiling hydrocarbons than do summer gasolines. Gasolines are characterized by the following indexes: a tendency toward the formation of deposits (existent resin content), corrosional aggressiveness (acidity and sulfur content), and stability in storage (induction period and period of stability).
The major performance characteristic of gasolines is their antiknock rating—that is, the ability to burn normally in a motor under various conditions. The antiknock properties of gasolines are rated by the octane rating and, for aviation gasolines, by the performance rating as well. The higher the octane or performance rating of a gasoline, the better its antiknock properties. The division of gasolines into grades is based on these properties: for automotive gasolines, the value of the octane rating is given (A-66, A-72, AI-93); aviation
|Table 1. Grades and quality of automotive gasolines manufactured in the USSR|
|1 For AI–98 gasoline there is no division Into summer and winter types; for the other gasolines, the numerator gives the summer value and the denominator gives the winter value.|
|Minimum octane rating by the motor method||66||72||76||85||89|
|Maximum tetraethyl lead content (g/kg)||0.6||—||0.41||0.82||0.82|
|Minimum temperature of start of distillation (°C)||35||35||35||35||35|
|Maximum end point of boiling (°C)||205/185||195/185||195/185||195/185||1951|
|Maximum pressure of saturated vapors|
|(kilonewtons per sq m)||670/930||670/930||670/930||670/930||670|
|(mm of mercury)||500/700||500/700||500/700||500/700||500|
|Minimum induction period (min)||450||600||900||900||900|
|Maximum acidity, KOH (mg/l)||30||30||30||30||30|
|Maximum (existent) resin content (mg/l)||150||100||100||70||70|
|Maximum sulfur content (%)||0.15||0.12||0.10||0.10||0.10|
|Table 2. Grades and quality of aviation gasolines manufactured in the USSR|
|minimum octane rating by the motor method||98.6||95||91||70|
|minimum performance rating for a rich mixture||130||130||115||—|
|Maximum tetraethyl lead content (g/kg)||2.7||3.3||2.5||—|
|Minimum temperature of start of distillation (°C)||40||40||40||40|
|Maximum end point of boiling (°C)||180||180||180||180|
|Maximum acidity, KOH (mg/l)||10||10||10||10|
|Maximum (existent) resin content (mg/l)||20||20||20||20|
|Maximum sulfur content (%)||0.05||0.05||0.05||0.05|
|Period of stability (hr)||8||8||8|
gasolines (except B-70) are graded by a fraction (B-100/130, B-91/115), where the numerator is the octane rating and the denominator is the performance rating. An antiknock agent, tetraethyl lead, is added to gasolines to increase their antiknock rating. Such ethylated gasolines are toxic, and precautionary measures are necessary when working with them; they must be dyed to distinguish them from nonethylated gasolines.
Effect on the organism Gasoline passes into the organism mainly through the lungs. The danger of gasoline poisoning exists at all stages of its production and transportation and particularly in its use. The maximum permissible concentration of gasoline vapors in air is 100–300 mg/m3; for solvent gasoline it is 300 mg/m3. In acute poisoning by gasoline vapors, headache, unpleasant sensations in the throat, coughing, and irritation of the mucous membranes of the eye and nose develop; in serious cases dizziness, unsteady walk, psychic excitation, slowing of pulse, and sometimes loss of consciousness result. For chronic poisoning the usual complaints include headaches, dizziness, sleep disorders, irritability, increased fatigability, loss of weight, and pains in the region of the heart.
First aid and medical treatment Treatment of acute poisoning includes fresh air, oxygen, and cardiac and tranquilizing agents; in cases of stoppage of breathing, artificial respiration is used. In case of entry of gasoline into the stomach, 30–50 g of vegetable oil are given internally. In cases of chronic poisoning, general restorative treatment, physiotherapy, and temporary removal from work with gasoline are required. Persons suffering from functional illnesses of the nervous system and endocrine organs are not allowed to work with gasoline.
REFERENCESNefteprodukty: Svoistva, kachestvo, primenenie: Spravochnik. Moscow, 1966.
Vrednye veshchestva v promyshlennosti, 4th ed., part 1. Editor in chief, N. V. Lazareva. Leningrad, 1963.
Professional’nye bolezni, 2nd ed. Moscow, 1964.
A. A. GUREEV
a mixture of light liquid hydrocarbons obtained during the distillation of petroleum or the separation of industrial gases. Gasoline is a readily combustible and dangerously explosive liquid that is used as a fuel for carburetor internal-combustion engines (natural gasoline with a boiling range of 30° C to 200° C), as a solvent for the extraction of oils and resinated substances (fraction 70° C to 100° C), for laboratory analysis (petroleum ether with a boiling range of 30° C to 80° C), and for other purposes. Gasoline as a single commercial product with precisely standardized properties is not produced industrially.