prEN 16715

Liquid petroleum products - Determination of ignition delay and derived cetane number (DCN) of middle distillate fuels - Ignition delay and combustion delay determination using a constant volume combustion chamber with direct fuel injection

This document specifies a test method for the quantitative determination of ignition and combustion delays of middle distillate fuels intended for use in compression ignition engines. The method utilizes a constant volume combustion chamber with direct fuel injection into heated, compressed synthetic air. A dynamic pressure wave is produced from the combustion of the product under test. An equation is given to calculate the derived cetane number (DCN) from the ignition and combustion delays determined from the dynamic pressure curve.
This document is applicable to middle distillate fuels, fatty acid methyl esters (FAME) and blends of diesel fuels and FAME. The method is also applicable to middle distillate fuels of non-petroleum origin, oil-sands based fuels, blends of fuel containing biodiesel material, diesel fuel oils containing cetane number improver additives and low-sulphur diesel fuel oils. However, users applying this document especially to unconventional distillate fuels are warned that the relationship between derived cetane number and combustion behaviour in real engines is not yet fully understood.
This document covers the ignition delay range from 2,6 ms to 3,9 ms and combustion delay from 3,78 ms to 6,56 ms (62,78 DCN to 39,44 DCN).
NOTE   The combustion analyser can measure shorter or longer ignition and combustion delays, but precision is not known.
WARNING - The use of this document can involve hazardous materials, operations and equipment. This document does not purport to address all of the safety problems associated with its use. It is the responsibility of users of this document to take appropriate measures to ensure the safety and health of personnel prior to application of the document, and fulfil statutory and regulatory requirements for this purpose.

Flüssige Mineralölerzeugnisse - Bestimmung des Zündverzugs und der abgeleiteten Cetanzahl (ACZ) von Kraftstoffen aus Mitteldestillaten - Bestimmung des Zündverzugs und des Verbrennungsverzugs in einer Verbrennungskammer mit konstantem Volumen und direkter Kraftstoffeinspritzung

Dieses Dokument legt ein Prüfverfahren zur quantitativen Bestimmung des Zündverzugs und des Verbrennungsverzugs von Kraftstoffen aus Mitteldestillaten fest, die in Dieselmotoren eingesetzt werden. Dieses Verfahren nutzt eine Verbrennungskammer mit konstantem Volumen mit direkter Kraftstoffeinspritzung in erwärmte und komprimierte synthetische Luft. Durch die Verbrennung des zu prüfenden Produkts wird eine dynamische Druckwelle erzeugt. Eine Gleichung zur Berechnung der abgeleiteten Cetanzahl (ACZ) mit den anhand der dynamischen Druckkurve ermittelten Werte für den Zünd- und den Verbrennungsverzug ist angegeben.
Dieses Dokument gilt für Mitteldestillatkraftstoffe, Fettsäuremethylester (FAME) sowie Gemische aus Dieselkraftstoffen und FAME. Das Verfahren ist ebenfalls auf Mitteldestillatkraftstoffe nicht mineralölstämmiger Herkunft, auf ölsandbasierte Kraftstoffe, auf Biodieselmaterial enthaltende Kraftstoffmischungen, auf Dieselkraftstoffe, welche Zündverbesserer enthalten und auf schwefelarme Dieselkraftstoffe anwendbar. Anwender, die dieses Dokument im Besonderen auf alternative Destillatkraftstoffe anwenden, werden jedoch darauf hingewiesen, dass die Beziehung zwischen der abgeleiteten Cetanzahl und dem Verbrennungsverhalten in realen Motoren noch nicht völlig geklärt ist.
Dieses Dokument umfasst den Zündverzugsbereich von 2,6 ms bis 3,9 ms und den Verbrennungsverzugsbereich von 3,78 ms bis 6,56 ms (ACZ 62,78 bis ACZ 39,44).
ANMERKUNG   Das Verbrennungsprüfgerät kann einen kürzeren oder längeren Zündverzug und Verbrennungsverzug messen, die Präzision ist jedoch nicht bekannt.
WARNUNG - Die Anwendung dieses Dokuments kann die Anwendung gefährlicher Stoffe, Arbeitsgänge und Geräte mit sich bringen. Dieses Dokument beansprucht nicht, alle damit verbundenen Sicherheitsprobleme zu behandeln. Es liegt in der Verantwortung des Anwenders dieses Dokuments, vor dessen Anwendung geeignete Maßnahmen für die Sicherheit und den Gesundheitsschutz des Personals zu ergreifen, und dafür Sorge zu tragen, dass behördliche und gesetzliche Maßnahmen eingehalten werden.

Produits pétroliers liquides - Détermination du délai d'inflammation et de l'indice de cétane dérivé (ICD) des distillats moyens - Détermination du délai d'inflammation et de combustion en utilisant une chambre à volume constant avec injection directe du carburant

Le présent document spécifie une méthode d'essai pour la détermination quantitative des délais d’inflammation et de combustion des distillats moyens utilisés comme carburants dans les moteurs à allumage par compression. Cette méthode utilise une chambre de combustion à volume constant avec injection directe de carburant dans de l'air synthétique comprimé et chauffé. Une onde de pression dynamique est générée par la combustion du produit soumis à l'essai. Une équation est donnée pour calculer l'indice de cétane dérivé (ICD) à partir des délais d’inflammation et de combustion déterminés à partir de la courbe de pression dynamique.
Le présent document s'applique aux distillats moyens, aux esters méthyliques d’acides gras (EMAG) et aux mélanges de carburants diesel et d'EMAG. La méthode est également applicable aux distillats moyens d'origine non pétrolière, aux carburants produits à partir de sables asphaltiques, aux mélanges de carburants contenant du biodiesel, aux carburants diesel contenant des additifs améliorateurs de cétane et aux carburants diesel à faible teneur en soufre. Cependant, l'attention des utilisateurs du présent document, en particulier lorsqu’il est appliqué aux distillats combustibles non conventionnels, est attirée sur le fait que la relation entre l'indice de cétane dérivé et les phénomènes de combustion dans les moteurs n’est pas encore parfaitement comprise.
Le présent document couvre les délais d'inflammation compris entre 2,6 ms et 3,9 ms et les délais de combustion compris entre 3,78 ms et 6,56 ms (ICD compris entre 39,44 et 62,78).
NOTE   L’analyseur de combustion peut mesurer des délais d’inflammation et de combustion plus longs ou plus courts, mais la fidélité n’est pas connue.
ATTENTION - L'utilisation du présent document peut impliquer la mise en œuvre de produits, d'opérations et d'équipements à caractère dangereux. Le présent document n'est pas censé aborder tous les problèmes de sécurité concernés par son usage. Il est de la responsabilité des utilisateurs de ce document de prendre les mesures appropriées pour assurer la sécurité et préserver la santé du personnel avant son application, et pour répondre aux exigences réglementaires et statutaires à cette fin.

Tekoči naftni proizvodi - Ugotavljanje zakasnitve vžiga in izpeljanega cetanskega števila (DCN) v srednje destilatnih gorivih - Določanje zakasnitve vžiga in sežiga z uporabo komore s konstantno prostornino z direktnim injiciranjem goriva

General Information

• Status: Not Published
• Publication Date: 10-Aug-2026
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Drafting Committee: CEN/TC 19/WG 35 - Ignition quality testing and correlation
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 27-Mar-2025
• Due Date: 25-Mar-2025
• Completion Date: 27-Mar-2025
• Ref Project: oSIST prEN 16715:2025 - Liquid petroleum products - Determination of ignition delay and derived cetane number (DCN) of middle distillate fuels - Ignition delay and combustion delay determination using a constant volume combustion chamber with direct fuel injection

Relations

• Revises: EN 16715:2015 - Liquid petroleum products - Determination of ignition delay and derived cetane number (DCN) of middle distillate fuels - Ignition delay and combustion delay determination using a constant volume combustion chamber with direct fuel injection
• Effective Date: 06-May-2024

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-2025
Tekoči naftni proizvodi - Ugotavljanje zakasnitve vžiga in izpeljanega cetanskega
števila (DCN) v srednje destilatnih gorivih - Določanje zakasnitve vžiga in sežiga z
uporabo komore s konstantno prostornino z direktnim injiciranjem goriva
Liquid petroleum products - Determination of ignition delay and derived cetane number
(DCN) of middle distillate fuels - Ignition delay and combustion delay determination using
a constant volume combustion chamber with direct fuel injection
Flüssige Mineralölerzeugnisse - Bestimmung des Zündverzugs und der abgeleiteten
Cetanzahl (ACZ) von Kraftstoffen aus Mitteldestillaten - Bestimmung des Zündverzugs
und des Verbrennungsverzugs in einer Verbrennungskammer mit konstantem Volumen
und direkter Kraftstoffeinspritzung
Produits pétroliers liquides — Détermination du délai d'inflammation et de l'indice de
cétane dérivé (ICD) des distillats moyens — Détermination du délai d'inflammation et de
combustion en utilisant une chambre à volume constant avec injection direct du
carburant
Ta slovenski standard je istoveten z: prEN 16715
ICS:
75.160.20 Tekoča goriva Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2025
ICS 75.160.20 Will supersede EN 16715:2015
English Version
Liquid petroleum products - Determination of ignition
delay and derived cetane number (DCN) of middle
distillate fuels - Ignition delay and combustion delay
determination using a constant volume combustion
chamber with direct fuel injection
Produits pétroliers liquides - Détermination du délai Flüssige Mineralölerzeugnisse - Bestimmung des
d'inflammation et de l'indice de cétane dérivé (ICD) Zündverzugs und der abgeleiteten Cetanzahl (ACZ) von
des distillats moyens - Détermination du délai Kraftstoffen aus Mitteldestillaten - Bestimmung des
d'inflammation et de combustion en utilisant une Zündverzugs und des Verbrennungsverzugs in einer
chambre à volume constant avec injection direct du Verbrennungskammer mit konstantem Volumen und
carburant direkter Kraftstoffeinspritzung
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 19.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16715:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 7
5 Reagents and materials . 7
6 Apparatus . 8
7 Sampling . 8
8 Apparatus assembly and installation . 10
9 Preparation of apparatus . 10
9.1 System start-up and warm-up . 10
9.2 Standard operating and test conditions . 10
10 Calibration . 11
10.1 General. 11
10.2 Calibration, verification and quality control . 11
10.3 Apparatus verification . 12
10.4 Quality control (QC) . 13
11 Test procedure . 13
12 Calculation . 13
13 Expression of results . 14
14 Precision . 14
14.1 General. 14
14.2 Repeatability, r . 14
14.3 Reproducibility, R . 14
15 Test results . 15
Annex A (normative) Combustion analyser description . 16
Annex B (normative) Operational details in support to the standard test procedure . 19
Bibliography . 23

prEN 16725:2025 (E)
European foreword
This document (prEN 16715:2025) has been prepared by 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 document is currently submitted to the CEN Enquiry.
This document will supersede EN 16715:2015.
— introduction of the possibility of using a charge air blending system (6.2) and necessary instructions
on the quality control if this is used (under 10.4);
— revision of the correlation equation under Clause 12;
— update of precision statements under Clause 14;
— further clarification of the measurement range towards (39,44 to 62,78) derived cetane number
under Clause 1 in line with the revised ISO 4259-1:2017.
Introduction
This document is derived from joint standardization work within the Energy Institute and ASTM
International. It is based on and technically equivalent with ASTM D7668 [1].
The described method is an alternative quantitative determination of the cetane number of middle
distillate fuels intended for use in compression ignition engines. A correlation study between this method
and EN ISO 5165 [2] has been done and the results of this are incorporated in this document.
The basis of this method is the derived cetane number (DCN) correlation equation as given in Clause 12.
The on-going validation of the equation is monitored and evaluated through the existing American and
European fuel exchange programs. The validation data will be reviewed by CEN/TC 19 with a frequency
of at least every two years. As a result of the review, CEN/TC 19 may make the decision to, if necessary,
modify the existing equation/correlation or develop a new one. As part of this review, the sample types
will be examined, and if certain types are underrepresented, further steps may be taken to evaluate how
they perform.
The ignition delay (ID) and combustion delay (CD) values and the DCN value determined by this test
method provide a measure of the ignition characteristics of diesel fuel oil used in compression ignition
engines. This test is for use by engine manufacturers, petroleum refiners and marketers, and in commerce
as a specification aid to relate or match fuels and engines. This test is also applicable to non-conventional
diesel fuels, such as paraffinic diesel fuel.

For the original 2013 interlaboratory cooperative test programme results, see [3]. For the exchange programs
correlation data analysis see [4].
prEN 16725:2025 (E)
1 Scope
This document specifies a test method for the quantitative determination of ignition and combustion
delays of middle distillate fuels intended for use in compression ignition engines. The method utilizes a
constant volume combustion chamber with direct fuel injection into heated, compressed synthetic air. A
dynamic pressure wave is produced from the combustion of the product under test. An equation is given
to calculate the derived cetane number (DCN) from the ignition and combustion delays determined from
the dynamic pressure curve.
This document is applicable to middle distillate fuels, fatty acid methyl esters (FAME) and blends of diesel
fuels and FAME. The method is also applicable to middle distillate fuels of non-petroleum origin, oil-sands
based fuels, blends of fuel containing biodiesel material, diesel fuel oils containing cetane number
improver additives and low-sulphur diesel fuel oils. However, users applying this document especially to
unconventional distillate fuels are warned that the relationship between derived cetane number and
combustion behaviour in real engines is not yet fully understood.
This document covers the ignition delay range from 2,6 ms to 3,9 ms and combustion delay from 3,78 ms
to 6,56 ms (62,78 DCN to 39,44 DCN).
NOTE The combustion analyser can measure shorter or longer ignition and combustion delays, but precision
is not known.
WARNING — The use of this document can involve hazardous materials, operations and equipment. This
document does not purport to address all of the safety problems associated with its use. It is the
responsibility of users of this document to take appropriate measures to ensure the safety and health of
personnel prior to application of the document, and fulfil statutory and regulatory requirements for this
purpose.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 3170, Petroleum liquids — Manual sampling (ISO 3170)
EN ISO 3171, Petroleum liquids — Automatic pipeline sampling (ISO 3171)
EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696)
ISO 1998-2, Petroleum industry — Terminology — Part 2: Properties and tests
IP 537, Determination of the purity of Derived Cetane Number reference materials — Gas chromatography
method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1998-2 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
cetane number
CN
measure of the ignition performance of a diesel fuel in a standardized engine test on a scale defined by
reference fuels
Note 1 to entry: It is expressed as the percen
...