Octane number - the main indicator of the quality of gasoline, in itself has no physical meaning. It is a relative value used to determine the resistance of a fuel to spontaneous compression (knock) ignition.
Necessary
Test fuel, single cylinder engine, ideal blend of isooctane and n-heptane
Instructions
Step 1
Combustion of fuel in an engine is a complex chemical, physical and technical process that must be organized in such a way that combustion is as uniform as possible and the possibility of an explosion is minimal. The higher the octane number, the better the engine is protected. The counting is done under special conditions on a single-cylinder engine used for fuel testing. There are the most common methods for calculating octane numbers: exploratory (RON) and motor (MOR).
Step 2
RON characterizes the behavior of gasoline at low and medium loads and is calculated when working with a forced variable compression ratio. The test fuel is compared with a mixture of pure substances, isooctane and n-heptane, with conventionally accepted octane numbers of 100 and 0, respectively. That is, under ideal conditions, it is assumed that isooctane has the least detonation propensity, and n-heptane has the greatest. The tests determine the percentage of substances at which the engine operates in the same way as when using the tested gasoline. The octane number is taken as the percentage of isooctane. For example, RON 92 gasoline acts like an ideal fuel mixture of 92% isooctane and 8% n-heptane.
Step 3
MOF characterizes the behavior of gasoline under hard loads (for example, when driving uphill), the test conditions are closest to real ones. Also determined by comparison with ideal fuel.
Step 4
The RON and MOR values often differ up to 8-10 points, this difference characterizes how sensitive the fuel is when working with different loads. The arithmetic mean RON and RON are called the octane index, and they give a clearer idea of the engine's protection against spontaneous combustion.
