BS EN ISO 5163:2014

1   Scope This International Standard establishes the rating of liquid spark-ignition engine fuel in terms of an arbitrary scale of octane numbers using a standard single-cylinder, four-stroke cycle, variable-compression ratio, carburetted, CFR engine operated at constant speed. Motor octane number ( MON ) provides a measure of the knock characteristics of motor fuels in automotive engines under severe conditions of operation. The motor octane number provides a measure of the knock characteristics of aviation fuels in aviation piston engines, by using an equation to correlate to aviation-method octane number or performance number (lean-mixture aviation rating). This International Standard is applicable for the entire scale range from 0  MON to 120  MON , but the working range is 40  MON to 120  MON . Typical motor fuel testing is in the range of 80  MON to 90  MON . Typical aviation fuel testing is in the range of 98  MON to 102  MON . This International Standard is applicable for oxygenate -containing fuels containing up to 4,0 % ( m/m ) oxygen and for gasoline containing up to 25 % ( V / V ) ethanol.

   NOTE 1  Although 25 % ( V/V ) of ethanol corresponds to approximately 9 % ( m/m ) oxygen, full applicability of this test method for that oxygen range has only been checked for gasoline type of fu...