octane number

octane number
Every brand of gasoline has an octane rating or number which indicates its ability to resist knocking. When the numbers were first developed, the researchers found that normal heptane (a hydrocarbon) had almost no ability to resist knocking so they gave it an octane number of zero. Then they found that isooctane (also a hydrocarbon) was very resistant to knocking so they gave it the octane number of 100. To measure a particular sample of gasoline they discovered when it began to create detonation. Then they mixed isooctane to heptane to find out what percentage of isooctane created the same results as the sample of gasoline. In United States, there are two methods for determining the octane number depending upon operating conditions. The Research Octane Number (RON) is obtained when conditions are somewhat mild. The Motor Octane Number (MON) is obtained when conditions are somewhat severe and give a much lower number than the RON. The numbers on the gasoline pumps are usually an average of the RON and MON. Usually the pump number is about four numbers less than the RON. Thus if the automobile manufacturer recommends using gasoline with a RON of 91 or more, it would be acceptable to use pump gas rating of 87. The pump number is the anti-knock index which is half the sum of the RON and the MON.
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Dictionary of automotive terms. 2015.

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  • octane number — ☆ octane number or octane rating n. a number representing the antiknock properties of a gasoline, fuel mixture, etc., determined by the percentage of isooctane that must be mixed with normal heptane to produce the knocking quality of the fuel… …   English World dictionary

  • octane number —    or octane rating    a measure used to express the ability of gasoline to reduce engine knocking. Gasoline is a complex mixture of hydrocarbons: compounds containing hydrogen and carbon. Beginning chemistry students learn that octane is the… …   Dictionary of units of measurement

  • octane number — (of gasoline) a designation of antiknock quality, numerically equal to the percentage of isooctane by volume in a mixture of isooctane and normal heptane that matches the given gasoline in antiknock characteristics. Also called octane rating.… …   Universalium

  • octane number — 1. A measure of petrol s resistance to pre ignition or pinking , which is the sound made by an engine when pre ignition occurs, particularly at low revs and high load. Two measures are used, for low speed and high speed pre ignition. ULSP in the… …   Petroleum refining glossary

  • octane number — oktaninis skaičius statusas T sritis Standartizacija ir metrologija apibrėžtis Benzino antidetonacinių savybių rodiklis. atitikmenys: angl. octane number vok. Oktanzahl, f rus. октановое число, n pranc. indice d’octane, m; nombre d’octane, m …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • octane number — oktaninis skaičius statusas T sritis Standartizacija ir metrologija apibrėžtis Sutartinės skalės skaičius, reiškiantis degalų, skirtų benzininiams varikliams, atsparumą detonacijai. atitikmenys: angl. octane number vok. Oktanzahl, f rus.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • octane number — noun a measure of the antiknock properties of an automobile fuel; isooctane having an octane number of 100, a fuel with the same antiknock properties as a mixture of 90% isooctane and 10% heptane having an octane number of 90 …   Wiktionary

  • octane number — oktaninis skaičius statusas T sritis Energetika apibrėžtis Skaičius, apibūdinantis benzino ar žibalo detonacinį atsparumą. Pastarasis lyginamas su etaloninio mišinio, sudaryto iš izooktano C₈H₁₈ ir heksano C₇H₁₆, detonaciniu atsparumu. Izooktanas …   Aiškinamasis šiluminės ir branduolinės technikos terminų žodynas

  • octane number — oktaninis skaičius statusas T sritis chemija apibrėžtis Benzino antidetonacinių savybių rodiklis. atitikmenys: angl. octane number rus. октановое число …   Chemijos terminų aiškinamasis žodynas

  • octane number — noun Date: 1931 a number that is used to measure the antiknock properties of a liquid motor fuel (as gasoline) with a higher number indicating a smaller likelihood of knocking called also octane rating compare cetane number …   New Collegiate Dictionary

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