EN ISO 4264:2018

• Abstract:

  This document specifies a procedure for the calculation of the cetane index of middle-distillate fuels from petroleum-derived sources. The calculated value is termed the "cetane index by four-variable equation". Throughout the remaining text of this document, the term "cetane index" implies cetane index by four-variable equation.; This document is applicable to fuels containing non-petroleum derivatives from tar sand and oil shale. It is not applicable to pure hydrocarbons, nor to distillate fuels derived from coal. Cetane index calculations do not take into account the effects from additives used to enhance the Cetane number.; NOTE 1 This document was originally developed using a matrix of fuels, some of which contain non-petroleum derivatives from tar sands and oil shale.; NOTE 2 The cetane index is not an alternative way to express the cetane number; it is a supplementary tool, to be used with due regard for its limitations.; NOTE 3 The cetane index is used to estimate the cetane number of diesel fuel when a test engine is not available to determine this property directly, or when insufficient sample is available for an engine rating.; The most suitable range of fuel properties for application of this document is as follows:; Fuel property; Range; Cetane number; 32,5 to 56,5; Density at 15 °C, kg/m3; 805,0 to 895,0; 10 % (V/V) distillation recovery temperature, °C; 171 to 259; 50 % (V/V) distillation recovery temperature, °C; 212 to 308; 90 % (V/V) distillation recovery temperature, °C; 251 to 363; Within the range of cetane number (32,5 to 56,5), the expected error of the prediction via the cetane index equation will be less than ±2 cetane numbers for 65 % of the distillate fuels examined. Errors can be greater for fuels whose properties fall outside this range of application.; As a consequence of sample-specific biases observed, the expected error can be greater even when the fuel's properties fall inside the recommended range of application. Therefore, users can assess the required degree of prediction agreement to determine the fitness-for-use of the prediction.; NOTE 4 Sample specific biases were observed for distillate fuels containing FAME (fatty acid methyl ester).

• Status: Published
• Publication Date: 17-Jul-2018
• Withdrawal Date: 30-Jan-2019
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Drafting Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 18-Jul-2018
• Completion Date: 18-Jul-2018
• Ref Project: SIST EN ISO 4264:2018 - Petroleum products - Calculation of cetane index of middle-distillate fuels by the four variable equation (ISO 4264:2018)

• Replaces: EN ISO 4264:2007/A1:2013 - Petroleum products - Calculation of cetane index of middle-distillate fuels by the four-variable equation (ISO 4264:2007/Amd 1:2013)
• Effective Date: 01-Aug-2018
• Replaces: EN ISO 4264:2007 - Petroleum products - Calculation of cetane index of middle-distillate fuels by the four-variable equation (ISO 4264:2007)
• Effective Date: 01-Aug-2018
• Refers: ISO 91:2017 - Petroleum and related products — Temperature and pressure volume correction factors (petroleum measurement tables) and standard reference conditions
• Effective Date: 25-Aug-2026
• Refers: ISO 3924:2016 - Petroleum products — Determination of boiling range distribution — Gas chromatography method
• Effective Date: 25-Aug-2026
• Refers: ISO 12185:1996 - Crude petroleum and petroleum products — Determination of density — Oscillating U-tube method
• Effective Date: 25-Aug-2026
• Refers: ISO 3675:1998 - Crude petroleum and liquid petroleum products — Laboratory determination of density — Hydrometer method
• Effective Date: 25-Aug-2026
• Refers: ISO 3405:2011 - Petroleum products — Determination of distillation characteristics at atmospheric pressure
• Effective Date: 09-Feb-2026
• Refers: EN 1804-2:2020 - Machines for underground mines - Safety requirements for hydraulic powered roof supports - Part 2: Power set legs and rams
• Effective Date: 28-Jan-2026
• Refers: EN ISO 19439:2006 - Enterprise integration - Framework for enterprise modelling (ISO 19439:2006)
• Effective Date: 28-Jan-2026
• Refers: EN 7010:2020 - Aerospace series - Configuration - Definition and designation for product standards for externally threaded fasteners
• Effective Date: 28-Jan-2026
• Refers: EN 14382:2005/prA1 - Safety devices for gas pressure regulating stations and installations - Gas safety shut-off devices for inlet pressures up to 100 bar
• Effective Date: 28-Jan-2026
• Referred By: EN 61400-4:2013 - Wind turbines - Part 4: Design requirements for wind turbine gearboxes
• Effective Date: 09-Feb-2026
• Referred By: EN IEC 61400-4:2025 - Wind energy generation systems - Part 4: Design requirements for wind turbine gearboxes
• Effective Date: 09-Feb-2026
• Referred By: EN 81-43:2025 - Safety rules for the construction and installation of lifts - Special lifts for the transport of persons and goods - Part 43: Lifts for cranes
• Effective Date: 28-Jan-2026
• Referred By: EN 590:2022 - Automotive fuels - Diesel - Requirements and test methods
• Effective Date: 28-Jan-2026

Overview

EN ISO 4264:2018 specifies a standardized procedure to calculate the cetane index of middle-distillate fuels using the four-variable equation. The cetane index is a calculated estimate of diesel ignition quality derived from measured physical properties - not a substitute for engine-determined cetane number but a supplementary tool when an engine test is unavailable or sample size is limited. The standard applies to petroleum-derived middle-distillate fuels, including those containing non-petroleum derivatives from tar sand and oil shale, but excludes pure hydrocarbons and coal-derived distillates. Additives that modify cetane number are not accounted for in the calculation.

Key topics and requirements

• Input parameters: density at 15 °C and distillation recovery temperatures at 10%, 50%, and 90% (V/V).
• Calculation method: the official four-variable equation (uses the four measured variables) is the normative method; nomographs are provided in an informative annex as an alternative for practical use.
• Measurement standards: density and distillation temperatures must be determined using referenced methods (e.g., ISO 3675 or ISO 12185 for density; ISO 3405 for distillation). ISO 3924 may be used as an alternative to ISO 3405, but data must be converted to equivalent ISO 3405 values before calculation.
• Reporting: report the cetane index to the nearest 0.1 as “cetane index by four-variable equation.”
• Applicability ranges & precision: most suitable fuel property ranges are provided (cetane number 32.5–56.5; density 805–895 kg/m3; specific 10/50/90% distillation temperature ranges). Within the specified cetane number range, the expected prediction error is less than ±2 cetane numbers for about 65% of examined fuels. The standard warns of sample-specific bias (notably for fuels containing FAME).

Practical applications and users

• Quality control and fuel testing laboratories using EN ISO 4264:2018 to estimate diesel ignition quality when engine-testing is impractical.
• Refinery and blending operations monitoring fuel batch properties and compliance with diesel specifications.
• Regulatory bodies and procurement teams requiring a standardized, reproducible cetane index for specification verification or reporting.
• R&D and technical teams assessing middle-distillate fuel characteristics where rapid, non-engine-based estimates are needed.

Related standards

EN ISO 4264:2018 references and works with:

• ISO 3405 - determination of distillation characteristics
• ISO 3924 - GC boiling range distribution (alternative)
• ISO 3675 / ISO 12185 - density determination methods
• ISO 91 - temperature/pressure volume corrections

EN ISO 4264:2018 is a practical, standardized method for estimating cetane index that integrates with established fuel test methods and helps stakeholders compare and control middle-distillate fuel quality.

SLOVENSKI STANDARD
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SIST EN ISO 4264:2007/A1:2013
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Petroleum products - Calculation of cetane index of middle-distillate fuels by the four
variable equation (ISO 4264:2018)
Mineralölerzeugnisse - Berechnung des Cetanindex von Mitteldestillat-Kraftstoffen aus
der 4-Parameter-Gleichung (ISO 4264:2018)
Produits petroliers - Calcul de l'indice de cétane des distillats moyens par equation à
quatre variables (ISO 4264:2018)
Ta slovenski standard je istoveten z: EN ISO 4264:2018
ICS:
75.160.20 7HNRþDJRULYD Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 4264
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2018
EUROPÄISCHE NORM
ICS 75.160.20 Supersedes EN ISO 4264:2007
English Version
Petroleum products - Calculation of cetane index of
middle-distillate fuels by the four variable equation (ISO
4264:2018)
Produits petroliers - Calcul de l'indice de cétane des Mineralölerzeugnisse - Berechnung des Cetanindex
distillats moyens par equation à quatre variables (ISO von Mitteldestillat-Kraftstoffen aus der 4-Parameter-
4264:2018) Gleichung (ISO 4264:2018)
This European Standard was approved by CEN on 23 May 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4264:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 4264:2018) has been prepared by Technical Committee ISO/TC 28 "Petroleum
and related products, fuels and lubricants from natural or synthetic sources" in collaboration with
Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of
petroleum, synthetic and biological origin” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2019, and conflicting national standards shall
be withdrawn at the latest by January 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4264:2007.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4264:2018 has been approved by CEN as EN ISO 4264:2018 without any modification.

INTERNATIONAL ISO
STANDARD 4264
Third edition
2018-06
Petroleum products — Calculation of
cetane index of middle-distillate fuels
by the four variable equation
Produits pétroliers — Calcul de l'indice de cétane des distillats
moyens par équation à quatre variables
Reference number
ISO 4264:2018(E)
©
ISO 2018
ISO 4264:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 4264:2018(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Principle . 2
5 Procedure. 2
6 Calculation . 3
7 Expression of results . 3
8 Precision . 3
9 Test report . 3
Annex A (informative) Calculated cetane index by means of nomographs . 5
ISO 4264:2018(E)
Foreword
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This document was prepared by Technical Committee ISO/TC 28, Petroleum products and lubrica
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