The octane number - what does it mean?

Petrol in various quantities consumed worldwide.Its many varieties, but we, as always, I want to get the best quality product.To evaluate the different kinds of fuel use a special indicator - the octane number, and that can characterize the properties of gasoline.First of all it concerns its detonation properties and the possibility of using different grades of gasoline in modern engines

To understand what the octane number, you need to consider the processes occurring during engine operation.At first glance, everything is very simple - as the piston moves up the volume of the cylinder is reduced, which is in its fuel mix (a mixture in a certain proportion of air and gasoline vapor) is compressed.The candle gives a spark lights up the mixture, and the resulting pair of combustion, significantly increasing in volume, move the piston down.

described looks good in a scheme, but actually in the process there are many nuances that can significantly change the picture.Leaving aside the subtleties of the

engine, take a closer look combustion.Usually occurs quiet, smooth combustion.During this process, several intermediates formed.They differ instability, and when a certain concentration of explosive combustion can occur.

It will be a completely different process.The speed of propagation of the flame during normal burning - tens of meters per second, while the explosive combustion - up to 2500 m / s.In this case, parts of the motor acts excessive load, there are unusual engine noise and knocks.Such sharp, ringing sound experienced drivers simply characterize - "knocking fingers", which is the first sign of a detonation and a negative impact on the performance of the engine.

anti-knock properties of gasoline just characterizes the octane number.You can now go back to the motor.The fact is that designers are always concerned about obtaining more power from the same engine, ceteris paribus.The easiest way - to increase the compression ratio of the engine.

When increasing the compression ratio of the fuel mixture in the process of combustion releases more energy, thus increasing the engine power.Here octane and characterizes various grades of gasoline for their propensity to detonation.The higher the value, the lower the probability of detonation.Her ability to define the content of different hydrocarbons in the fuel.In order to establish anti-knock resistance is typically used two ways - motor and research.

procedure for measuring the octane number in each case has its own, and its value will be different for each form of measurement.The result is displayed in the designation of the brand of gasoline.Gasoline, a method proven by the motor is, for example, A-92, and on research - AI-92.The higher the octane number, the higher the fuel detonation resistance, and its quality is considered the best.

To increase the resistance to detonation in low grade gasoline is added which reduce the tendency to knock - antidetonators, whereby gasoline can be used as high-octane.One of them is tetraethyl lead.Thanks to it, and other additives used in conjunction with it, the ability to decrease the detonation of the combustible mixture and increases the octane number.Gasoline, in which these additives are added, referred to as leaded.In order to distinguish from the usual, it stained.Fuel knock resistance gets a boost, but this gasoline is considered poisonous, and in many countries it is not recommended for use.

used as fuel and gas.When using detonation problems do not arise, because the octane number of the gas above: it is the average of 105 units.

The material provides insight into the various grades of gasoline, the quality and characteristics.An explanation of the cause of the detonation and impact on the properties of octane gasoline.