Gasoline is a speific fuel for gasoline engine, chiefly categorized into automobile gasoline, automobile ethanol gasoline and automobile gasoline compliant to the local standard.
1.Properties
（1）Appearance: white with clarity, lighter than water, density normally at 0.71~0.75g/cm3, weight equivalent to 3/4 that of water’s, with characteristic aromatic odor, few bubbles generated when shaken, which disappear quickly, highly volatile, feeling cool and sticky;
（2）Required performance: mostly in terms of evaporability, anti-knock, stability, corrodibility, cleanness and environmental requirement;
①Evaporability: On one hand, gasoline shall vaporize into ignitable gasoline-air mixture rapidly under cold weather to ensure that the engine will ignite and start in cold weather, on the other hand, to ensure safe and stable operation of the engine, the gasoline shall not give rise to vapor impedance( vapor lock) under hot weather (e.g. summer).
②Anti- knock: Anti- knock refers to performance of avoiding knocks when gasoline burns inside the engine. The anti-knock performance increases with higher grade of gasoline, that is, #97 mogas has a better anti-knock performance than #90 and #93 mogas.
③Stability: The oxidation stability of gasoline is its resistance to oxidation at normal temperature and in liquid phase. For gasoline with good stability, elongated storage will not lead to great change in its quality, while the gasoline with poor stability is susceptible to oxidation during storage and transport, giving rise to gums and acidic contaminants with comparatively higher molecular weight, which reduces the octane number and increases the acidity with darker color.
④Corrosive action: Corrosive action indicates whether the gasoline corrodes metallic equipment and parts directly or indirectly. The smaller the corrosive action is, the better the gasoline.
⑤Cleanness: Cleanness indicates moisture content and mechanical impurities content in the gasoline. With water in the gasoline, the performance of the engine will be affected, which is well shown when a car runs in an interrupted manner repeatedly. With impurities in the gasoline, its appearance quality will be impacted, and at the same time, the filter can be plugged, leading to blockage of the oil circuit. The interrupted fuel supply will also affect the normal operation of the engine.
⑥Environmental requirement: Environment requirement indicates the extent of harm and severity for the gasoline itself, its vapor and the tail gas arising from its combustion. As these factors are harmful to human health and the environment to certain degrees, SSPC attaches great importance to the occupational hygiene and protection while making continuous efforts through technological renovation (such as gas vapor recovery) to reduce the vapor density at workplace and mitigate the hazard to human health and the environment.
2.Categories and Grades
（1）Automobile gasoline: It is classified into automobile gasoline II and III by sulfur content or other criteria as per GB17930－2006. As for grade, it is classified into #90, #93 and #97 by RON.
（2）Automobile ethanol gasoline: It is classified into #90, #93 and #97 by RON as per GB18351－2004.
In addition, automobile gasoline’s grades are classified into #90, #93 ,#97 and #98 by RON in accordance with local and company standards, such as relevant criteria of Beijing city.
Selection
Select different grades of gasoline according to the vehicle type and the engine compression ratio. The higher the compression ratio is, the higher the grade is needed.
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Compression Ratio
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Grade
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7.5－8.0
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90－93
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8.0－8.5
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93
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8.5－9.0
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97
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9.0
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97－98
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