The division into different categories of petrol is made depending on the value of its octane rating.
This is the main indicator that determines not only the actual quality of gasoline, but also its chemical properties.
The concept of octane
Fractional distillation underthe influence of different temperatures are obtained various kinds of fuels (including gasoline) lubricants, as well as products for petrochemical synthesis. This, no doubt, know all who visited the chemistry lessons at school. However, approaching the gas station, you will surely have repeatedly drawn attention to the mysterious figures are divided into different types of gasoline. What is their real difference?
These same figures in the marking of petrol representits octane number. This is the main criterion by which classified different types of gasoline. The term "octane" fuel property characterizes burn freely in the engine under a variety of conditions. The higher the number, the fuel is more resistant to self-ignition by compression. However, to obtain high-octane gasoline production at a slightly more complicated, in addition, it must be sufficiently clean.
Determination of anti-knock properties of gasoline
Each motor is designed to operate on fuelswith a certain octane number. In Russia, most of the car owners use AI92. These types of gasoline as AI95 and Ai98 usually allow themselves the owners of cars "premium" class. Diesel and Ai80 are still less in demand.
Determination of petrol resistance to detonationproduced by standard mixtures. The fact that a mixture of petrol equivalent heptane and isooctane. Accordingly, if the octane number of gasoline is equal to 92, it will self-ignite as the composition of 92% isooctane and 8% heptane.
Increasing gasoline octane
In the production of various types of gasolineMethod of mixing the fuel components is used. Otherwise, this process is called "compounding". As a result of all the necessary processes have received the products that fully meet the state standards and have accurate octane value.
Primary fractional distillation of crude oil producesgasoline with an octane index within 70. The quality of gasoline increases not only with the use of compounding, but also through the use of special additives, anti-knock. Previously, in order to improve the detonation properties of the fuel used tetraethyl lead. With all of that for a man this stuff is a potent poison. Currently used as high-octane additives ferrocene or methyl tertiary butyl ether, non-toxic so huge.