BS EN ISO 5165:2020 - Petroleum products. Determination of the ignition quality of diesel fuels. Cetane engine method
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BS EN ISO 5165:2020

Petroleum products. Determination of the ignition quality of diesel fuels. Cetane engine method

Status : Current   Published : August 2020



This document establishes the rating of diesel fuel oil in terms of an arbitrary scale of cetane numbers (CNs) using a standard single cylinder, four-stroke cycle, variable compression ratio, indirect injected diesel engine. The CN provides a measure of the ignition characteristics of diesel fuel oil in compression ignition engines. The CN is determined at constant speed in a pre-combustion chamber-type compression ignition test engine. However, the relationship of test engine performance to full scale, variable speed and variable load engines is not completely understood.

This document is applicable for the entire scale range from 0 CN to 100 CN but typical testing is in the range of 30 CN to 65 CN. An interlaboratory study executed by CEN in 2013 (10 samples in the range 52,4 CN to 73,8 CN)[3] confirmed that paraffinic diesel from synthesis or hydrotreatment, containing up to a volume fraction of 7 % fatty acid methyl ester (FAME), can be tested by this test method and that the precision is comparable to conventional fuels.

This test can be used for unconventional fuels such as synthetics or vegetable oils. However, the precision for those fuels has not been established and the relationship to the performance of such materials in full-scale engines is not completely understood.

Samples with fluid properties that interfere with the gravity flow of fuel to the fuel pump or delivery through the injector nozzle are not suitable for rating by this method.


This document specifies operating conditions in SI units but engine measurements are specified in inch-pound units or Fahrenheit because these are the historical units used in the manufacture of the equipment, and thus some references in this document include these and other non-SI units in parenthesis.

Standard NumberBS EN ISO 5165:2020
TitlePetroleum products. Determination of the ignition quality of diesel fuels. Cetane engine method
Publication Date12 August 2020
Normative References(Required to achieve compliance to this standard)ASTM D613, ISO 4787, ISO 3170, ISO 3696, ASTM D3703, ISO 3171, ASTM E832-81
Informative References(Provided for Information)ISO 3015, SAE J300
ReplacesBS EN ISO 5165:2018
International RelationshipsEN ISO 5165:2020,ISO 5165:2020
Draft Superseded By19/30399897 DC
DescriptorsDiesel fuels, Ignition, Fire tests, Calibration, Ignitability, Fuels, Testing conditions, Fuel oil, Quality, Automotive fuels, Cetane number, Petroleum products, Diesel engines
Title in FrenchProduits pétroliers. Détermination de la qualité d'inflammabilité des carburants pour moteurs diesel. Méthode cétane
Title in GermanMineralölerzeugnisse. Bestimmung der Zündwilligkeit von Dieselkraftstoffen. Cetan-Verfahren mit dem CFR-Motor
ISBN978 0 539 05768 3
File Size1.298 MB

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