EN ISO 5165:1998

SLOVENSKI STANDARD
01-november-1999
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Petroleum products - Determination of the ignition quality of diesel fuels - Cetane engine
method (ISO 5165:1998)
Mineralölerzeugnisse - Bestimmung der Zündwilligkeit von Dieselkraftstoffen - Cetan-
Verfahren mit dem CFR-Motor (ISO 5165:1998)
Produits pétroliers - Détermination de la qualité d'inflammabilité des carburants pour
moteurs diesel - Méthode cétane (ISO 5165:1998)
Ta slovenski standard je istoveten z: EN ISO 5165:1998
ICS:
75.160.20 7HNRþDJRULYD Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 5165
Third edition
1998-03-01
Petroleum products — Determination of the
ignition quality of diesel fuels — Cetane
engine method
Produits pétroliers — Détermination de la qualité d'inflammabilité des
carburants pour moteurs diesel — Méthode cétane
A
Reference number
ISO 5165:1998(E)
ISO 5165:1998(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard 5165 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants.
This third edition cancels and replaces the second edition (ISO 5165:1992), of which it constitutes a technical
revision.
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet central@iso.ch
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
INTERNATIONAL STANDARD  © ISO ISO 5165:1998(E)
Petroleum products — Determination of the ignition quality of
diesel fuels — Cetane engine method
WARNING – The use of this International Standard may involve hazardous materials, operations and
equipment. This International Standard does not purport to address all of the safety problems associated
with its use. It is the responsibility of the user of this International Standard to establish appropriate safety
and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard establishes the rating of diesel fuel oil in terms of an arbitrary scale of cetane numbers
using a standard single cylinder, four-stroke cycle, variable compression ratio, indirect injected diesel engine. The
cetane number provides a measure of the ignition characteristics of diesel fuel oil in compression ignition engines. The
cetane number 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, variable load engines is not
completely understood.
This International Standard is applicable for the entire scale range from zero cetane number (CN) to 100 CN but typical
testing is in the range of 30 CN to 65 CN.
This test may be used for unconventional fuels such as synthetics, vegetable oils, etc. However, 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.
NOTE 1 This International Standard specifies operating conditions in SI units but engine measurements are specified in
inch-pound units because these are the units used in the manufacture of the equipment, and thus some references in this
International Standard include these units in parenthesis.
NOTE 2 For the purposes of this International Standard, the expression “% (V/V)” is used to represent the volume fraction of
a material.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 3015:1992, Petroleum products – Determination of cloud point.
ISO 3170:1988, Petroleum liquids – Manual sampling.
ISO 3171:1988, Petroleum liquids – Automatic pipeline sampling.
ISO 3696:1987, Water for analytical laboratory use – Specification and test methods.
ISO 4787:1984, Laboratory glassware – Volumetric glassware – Methods for use and testing of capacity.
© ISO
ISO 5165:1998(E)
ASTM D 613-95, Standard test method for cetane number of diesel fuel oils.
ASTM E 832-81, Specification for laboratory filter papers.
3 Principle
The cetane number of a diesel fuel oil is determined by comparing its combustion characteristics in a test engine with
those for blends of reference fuels of known cetane number under standard operating conditions. This is accomplished
using the bracketing handwheel procedure which varies the compression ratio (handwheel reading) for the sample and
each of two bracketing reference fuels to obtain a specific ignition delay permitting interpolation of CN in terms of
handwheel reading.
4 Definitions
For the purposes of this International Standard, the following definitions apply.
4.1
cetane number
Measure of the ignition performance of a diesel fuel oil obtained by comparing it to reference fuels in a standardized
engine test. Ignition performance is understood to mean the ignition delay of the fuel as determined when the standard
test engine is operated under controlled conditions of fuel flow rate, injection timing and compression ratio.
4.2
compression ratio
The ratio of the volume of the combustion chamber including the pre-combustion chamber with the piston at bottom
dead center (b.d.c.) to the comparable volume with the piston at top dead center (t.d.c.)
4.3
ignition delay
Period of time between the start of fuel injection and the start of combustion. It is expressed in degrees of crank
angle rotation.
4.4
injection timing; injection advance
Time in the combustion cycle at which fuel injection into the combustion chamber is initiated. It is expressed in degrees
of crank angle.
4.5
handwheel reading
Arbitrary numerical value, related to compression ratio, obtained from a micrometer scale that indicates the position
of the variable compression plug in the pre-combustion chamber of the engine.
4.6
cetane meter; ignition delay meter
An electronic instrument which displays injection advance and ignition delay derived from input pulses of multiple
transducers (pickups).
4.7
injector opening pressure
Fuel pressure that overcomes the resistance of the spring which normally holds the injector nozzle pintle closed,
and thus forces the pintle to lift and release an injection spray from the nozzle.
4.8
reference pickup
Transducer(s) mounted over the flywheel of the engine, triggered by a flywheel pointer, used to establish a t.d.c.
reference and a time base for calibration of the ignition delay meter.
© ISO
ISO 5165:1998(E)
4.9
injector pickup
Transducer to detect motion of the injector pintle, thereby indicating the beginning of injection.
4.10
combustion pickup
Pressure transducer exposed to cylinder pressure to indicate the start of combustion.
4.11
primary reference fuels
Hexadecane (cetane), heptamethylnonane (HMN) and volumetrically proportioned mixtures of these materials
which now define the CN scale by the relationship given in the following equation:
CN = % cetane + 0,15 (% HMN) . . . (1)
NOTE 3 The arbitrary CN scale was originally defined as the volume percent of cetane in a blend with 1-methylnaphthalene
(AMN) where cetane had an assigned value of 100 and AMN an assigned value of zero. A change from 1-methylnaphthalene
to heptamethylnonane as the low CN ingredient was made in 1962 to utilize a material of better stability and availability.
Heptamethylnonane was determined to have a CN of 15 based on engine calibration by the ASTM Diesel National Exchange
Group, using blends of cetane and AMN as primary reference fuels. The use of 1-methylnaphthalene as a primary reference
fuel is allowed.
4.12
secondary reference fuels
Volumetrically proportioned blends of two selected hydrocarbon mixtures designated “T fuel” (high CN) and “U fuel”
(low CN) where each numbered paired set of “T fuel” and “U fuel” is calibrated by the ASTM Diesel National
Exchange Group in various combinations by comparison to primary reference fuel blends.
4.13
check fuels
Diesel fuel oils calibrated by the ASTM Diesel National Exchange Group which provide a guide for an individual
laboratory to check the cetane rating performance of a specific engine unit.
5 Reagents and reference materials
water conforming to grade 3 of ISO 3696. Water shall be used in the cylinder jacket for
5.1 Cylinder jacket coolant,
laboratory locations where the resultant boiling temperature is 100 °C ± 2 °C. Water with commercial glycol-based
antifreeze added in sufficient quantity to meet the boiling temperature requirement shall be used when the laboratory
altitude dictates. A commercial multi-functional water-treatment material should be used in the coolant to minimize
corrosion and mineral scale that can alter heat transfer and rating results.
An SAE 30 viscosity grade oil meeting service classification SF/CD or SG/CE
5.2 Engine crankcase lubricating oil.
2 2
shall be used. It shall contain a detergent additive and have a kinematic viscosity of 9,3 mm /s to 12,5 mm /s at 100 °C
and a viscosity index of not less than 85. Oils containing viscosity index improvers shall not be used. Multigraded
lubricating oils shall not be used.
hexadecane with a minimum purity of 99,0 %, as determined by chromatographic
5.3 Cetane primary reference fuel,
analysis, shall be used as the designated 100 cetane number component.
, 2,2,4,4,6,8,8-heptamethylnonane with a minimum purity of 98 %
5.4 Heptamethylnonane primary reference fuel
as determined by chromatographic analysis shall be used as the designated 15 cetane number component.
volumetric blends of two diesel fuels having widely different cetane numbers that
5.5 Secondary reference fuels,
have been round-robin engine calibrated by a recognized exchange testing group.
NOTE 4 Blends of “T fuel” and “U fuel” that have been engine calibrated by the ASTM Diesel National Exchange Group may
be and typically are used for routine testing. The calibration data are incorporated in blend tables that list the cetane numbers
assigned for various volume percentage blends of “T fuel” and “U fuel”. “T fuel” typically is in the range of 73 CN to 75 CN and
“U fuel” typically is in the range of 20 CN to 22 CN. These fuels are available from Phillips 66 Company, Bartlesville, OK, USA
and are examples of suitable products available commercially. This information is given for the convenience of users of this
International Standard and does not constitute an endorsement by ISO of these products.
© ISO
ISO 5165:1998(E)
NOTE 5 Storage and use of “T fuel” and “U fuel” should be at temperatures above 0 °C to avoid potential solidification,
particularly of “T fuel”. Before a container that has been stored at low temperature is placed in service, it should be warmed to a
temperature of at least 15 °C above its cloud point as determined in accordance with ISO 3015. It should be held at this
temperature for a period of at least 30 min and then the container should be thoroughly remixed.
5.6 Check fuels. Diesel fuel oils typical of the middle distillate type that have been engine calibrated by the ASTM
Diesel National Exchange Group.
NOTE 6 Low cetane check fuel will typically be in the range of 38 CN to 42 CN. High cetane check fuel will typically be in the
range of 50 CN to 55 CN.
6 Apparatus
6.1  Test engine assembly
As shown in figure 1 and comprising a single cylinder engine consisting of a standard crankcase with fuel pump
assembly, a cylinder with separate head assembly of the pre-combustion type (see figure 2), thermal-siphon
recirculating jacket coolant system, multiple fuel tank system with selector valving, injector assembly with specific
injector nozzle, electrical controls, and a suitable exhaust pipe. The engine shall be belt connected to a special
electric power-absorption motor which acts as a motor driver to start the engine and as a means to absorb power at
constant speed when combustion is occurring (engine firing). ASTM D 613, Annex A2 (Engine Equipment
Description and Specifications) lists all critical, non-critical and equivalent engine equipment which shall apply for
this International Standard.
6.2  Instrumentation
An electronic instrument to measure injection and ignition delay timing as well as conventional thermometry, gauges
and general purpose meters. ASTM D 613, Annex A3 (Instrumentation Description and Specifications) lists all
critical, non-critical and equivalent instrumentation which shall apply for this International Standard.
NOTE 7 Engine equipment and instrumentation are available from the single source manufacturer, Waukesha Engine
Division, Dresser Industries, Inc., 1000 West St. Paul Avenue, Waukesha, WI 53188, USA, fax: +1 414-549-2960. Waukesha
Engine Division also has authorized sales and service organizations in selected geographic areas.
6.3  Reference fuel dispensing equipment
Calibrated burettes or volumetric ware having a capacity of 400 ml to 500 ml and a maximum volumetric tolerance
of ± 0,2 %. Calibration shall be verified in accordance with ISO 4787. Burettes shall be outfitted with a delivery valve
and delivery tip to accurately control dispensed volumes. The delivery tip shall be of such size and design that shut-
off tip discharge does not exceed 0,5 ml. The rate of delivery from the dispensing system shall not exceed
500 ml/min.
NOTE 8 ASTM D 613, Appendix X1 (Reference Fuel Blending Apparatus and Procedures) provides additional information for
application of this International Standard.
6.4  Injector nozzle tester
The injector nozzle assembly shall be checked whenever the injector nozzle is removed and reassembled to ensure
that the initial pressure at which fuel is discharged from the nozzle is properly set.
NOTE 9 It is also important to inspect the type of spray pattern which occurs. Commercial injector nozzle testers which
include a lever-operated pressure cylinder, fuel reservoir and pressure gauge are available from several sources as common
diesel engine maintenance equipment.
6.5  Special maintenance tools
A number of specialty tools and measuring instruments are available for easy, convenient and effective
maintenance of the engine and testing equipment.
NOTE 10 Lists and descriptions of these tools and instruments are available from the manufacturers of the engine equipment
and those organizations offering engineering and service support for this International Standard.
© ISO
ISO 5165:1998(E)
Key
A Fuel tanks
B Air heater housing
C Air intake silencer
D Fuel flow-rate burette
E Combustion pickup
F Safety guard
G Variable compression plug
handwheel
H V.C.P. locking handwheel
I Flywheel pickups
J Oil filter cap
K Injection pump safety shutoff
solenoid
L Injector assembly
M Fuel injection pump
N Fuel selector valve
O OIl filter
P Crankcase oil heater control
Q Air heater switch
R Engine start-stop panel
S Instrument panel
T Intake air temperature controller
U Dual digital cetane meter
Figure 1 — Cetane method test engine assembly
7 Sampling and sample preparation
Samples shall be collected in accordance with ISO 3170, ISO 3171 or an equivalent National Standard.
Samples shall be brought to room temperature, typically 18 °C to 32 °C, before engine testing. If necessary, samples
shall be filtered through a Type 1, Class A filter paper, conforming to ASTM E 832, at room temperature and pressure
before engine testing.
8 Basic engine and instrument settings and standard operating conditions
8.1  Installation of engine equipment and instrumentation
Locate the cetane test engine in an area where it will not be affected by certain gases and fumes that may have a
measurable effect on the CN test result.
Installation of the engine and instrumentation requires placement of the engine on a suitable foundation and hook-up of
all utilities. Engineering and technical support for this function is required, and the user shall be responsible to comply
with all local and national codes and installation requirements. Proper operation of the test engine requires assembly of
a number of engine components and adjustment of a series of engine variables to prescribed specifications. Some of
these settings are established by component specifications, others are established at the time of engine assembly or
after overhaul and still others are engine-running conditions that shall be observed and/or determined by operator
adjustment during the testing process.
© ISO
ISO 5165:1998(E)
Key
1 V.C.P. locking wheel 6 Precombustion chamber
2 V.C.P. handwheel 7 Cylinder head
3 V.C.P. micrometer 8 Injector nozzle assembly
4 Variable compression plug 9 Cylinder
5 Combustion pickup hole 10 Turbulence passage
Figure 2 — CFR engine cylinder head and handwheel assembly
8.2  Engine speed
The engine speed shall be 900 r/min ± 9 r/min when the engine is operating with combustion with a maximum variation
of 9 r/min occurring during a rating. Engine speed when combustion is occurring shall not be more than 3 r/min greater
than for motoring without combustion.
8.3  Valve timing
The engine shall use a four-stroke cycle with two crankshaft revolutions for each complete combustion cycle. The two
critical valve events are those that occur near top-dead-center (t.d.c.); intake valve opening and exhaust valve closing.
Intake valve opening shall occur 10,0° ± 2,5° after-top-dead-center (a.t.d.c.) with closing at 34° after-bottom-dead-
center (a.b.d.c.) on one revolution of the crankshaft and flywheel. Exhaust valve opening shall occur 40° before-
bottom-dead-center (b.b.d.c.) on the second revolution of the crankshaft or flywheel with closing at 15,0° ± 2,5° a.t.d.c.
on the next revolution of the crankshaft or flywheel. ASTM D 613, Annex A4 (Apparatus Assembly and Setting
Instructions) defines the procedures for camshaft timing which shall apply for this International Standard.
8.4  Valve lift
Intake- and exhaust- cam lobe contours, while different in shape, shall have a contour rise of 6,223 mm to 6,350 mm
(0,245 in to 0,250 in) from the base circle to the top of the lobe so that the resulting valve lift shall be
6,045 mm ± 0,05 mm (0,238 in ± 0,002 in). ASTM D 613, Annex A4 (Apparatus Assembly and Setting Instructions)
defines the procedures for measuring valve lift which shall apply for this International Standard.
8.5  Fuel pump timing
Closure of the pump plunger inlet port shall occur at a flywheel crank angle between 300° and 306° on the engine
compression stroke when the fuel flow-rate-micrometer is set to a typical operating position and the variable timing
device lever is at full advance (nearest to operator). See ASTM D 613, Annex A4 (Apparatus Assembly and Setting
© ISO
ISO 5165:1998(E)
Instructions) for detailed instructions on setting and checking the fuel pump timing which shall apply for this
International Standard.
8.6  Fuel pump inlet pressure
A minimum fuel head established by assembly of the fuel tanks (storage reservoirs) and flow-rate-measuring burette so
that the discharge from them is 635 mm ± 25 mm above the centerline of the fuel injection pump inlet.
8.7  Direction of engine rotation
Clockwise rotation of the crankshaft shall occur when observed from the front of the engine.
8.8  Injection timing
This shall occur 13,0° b.t.d.c. for the sample and reference fuels.
8.9  Injector nozzle opening pressure
This shall be 10,3 MPa ± 0,34 MPa.
8.10  Injection flow rate
This shall be (13,0 ± 0,2) ml/min [(60 ± 1)s/13,0 ml].
8.11  Injector coolant passage temperature
This shall be 38 °C ± 3 °C.
8.12  Valve clearances
Setting the clearance between each valve stem and valve rocker half-ball to the following approximate measurements,
upon assembly with the engine cold prior to being operated, will typically provide the controlling engine-running and hot
clearance:
— intake valve 0,075 mm (0,004 in);
— e
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