Knock aviation fuel

Antiknock gasoline a gasoline to which a low percentage of tetra-ethyl-lead, or similar compound, has been added to increase octane number and eliminate knocking. Such gasolines have an octane number of 100 or more and are now used chiefly as aviation fuel. 

Ethylbenzene has been added to motor and aviation fuels because of its anti-knock properties. Estimates of ethylbenzene in gasoline have ranged from < 1-2.7% (Fishbein, 1985 lARC, 1989 Backer eta/., 1997). 

Heptane is used as the knock-testing standard for octane rating measurements. An isomer, triptane (2,2,3-trimethyl butane), is used in aviation fuel. All isomers are used in organic syntheses and are ingredients of gasoline, rubber solvent naptha, and other petroleum mixtures that are utilized as fuels or solvents. 

D27(X) Test Method for Knock Oiaracteristics of Motor and Aviation Fuels by the Motor Method ... 

This value is primarily used to rate the antiknock values of aviation gasolines with octane numbers over 100. It is defined as the maximum knock-free power output obtained from fuel expressed as a percentage of the power obtainable from isooctane. The relationship between octane number and performance number is listed as follows ... 

Ogilivie et al(Ref 4) found that bromopicrin, choloropicrin, Br other compds caused an increase in the knocking tendency in aviation gasoline. These compds counteracted the effect of antiknock additives also had some effect on the base stock fuel... 

Other tests have been used in the past, particularly for aviation gasoline, where it was more important to discriminate accurately between fuels with ON > 100. These had the advantage of being more related to real physical phenomena. For example, the performance number [11] was based on a single standard fuel, iso-octane, and the relative indicated mean effective power (imep) (defined in terms of the cylinder pressure [3]), and so is directly related to combustion. The performance number was 100 times the ratio of the knock limited imeps of the fuel and iso-octane. Much of the API 45 project on octane number of mixtures of pure hydrocarbons (see Section 7.2.5) was reported in terms of performance number. This project of the American Petroleum Institute ran from 1938 to 1957, and has provided an invaluable source of basic data. The articles by Lovell [10] and Scott [12] review and interpret these data. Whilst this criterion and these values of CCRs [10,13] are no longer in widespread use for automotive fuels, the data available in the older literature could still be useful in testing chemical models. Because the octane number scale is based on two reference fuels, modelling the octane number of any hydro-... 

Note that the fuel is aviation 100 LL gasoline with higher Octane number than regular one. This selection makes more resistance against knock phenomena. 

D2624, Electrical conductivity of aviation and distillate fuels D2699, Knock characteristics by research octane X X X ... 

A fuel additive used to minimize ice formation. Chemical compounds added to motor and aviation gasolines to improve fheir performance and to reduce knock in spark-ignition engines. 

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