IP 617: Determination of generic cetane number (G-CN) of fuels using a constant volume combustion chamber — primary reference fuels calibration (PRFC) method

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  • Method adopted/last revised: 2017
  • Method reapproved: None
  • REF/ISBN: IP617-2939444
  • Status: New
  • First printed in STM books: February 2017


This standard specifies a method for the quantitative determination of the generic cetane number (G-CN) of middle distillate fuels and blending components, intended for use in compression ignition engines. The method is applicable to middle distillate fuels of both petroleum and non-petroleum origin, hydrocarbon oils, oil-sands based fuels, blending components, fatty acid methyl esters (FAME), blends of fuel containing biodiesel material, diesel fuel oils containing cetane number improver additives and low-sulfur diesel fuel oils, over the calibrated range of 35 G-CN to 85 G-CN. However, users applying this standard especially to unconventional distillate fuels are warned that the relationship between cetane number and combustion behaviour in real engines is not yet fully understood.

NOTE 1 The analyser can measure G-CN outside the calibrated range, but precision has not been determined.

NOTE 2 For the purpose of this standard, the expression “% (V/V)” is used to represent the volume fraction.

NOTE 3 For the purpose of this standard, the abbreviation G-CN (Generic Cetane Number) is being used to discriminate it from other techniques. This test method uses blends of primary reference materials for calibration. It aligns with the concept of a generic test method currently in development in Europe.

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