ASTM D6890-22

Standard Test Method for Determination of Ignition Delay and Derived Cetane Number (DCN) of Diesel Fuel Oils by Combustion in a Constant Volume Chamber

SIGNIFICANCE AND USE
5.1 The ID and DCN values determined by this test method can provide a measure of the ignition characteristics of diesel fuel oil in compression ignition engines.  
5.2 This test can be used in commerce as a specification aid to relate or match fuels and engines. It can also be useful in research or when there is interest in the ignition delay of a diesel fuel under the conditions of this test method.  
5.3 The relationship of diesel fuel oil DCN determinations to the performance of full-scale, variable-speed, variable-load diesel engines is not completely understood.  
5.4 This test may be applied to non-conventional fuels. It is recognized that the performance of non-conventional fuels in full-scale engines is not completely understood. The user is therefore cautioned to investigate the suitability of ignition characteristic measurements for predicting performance in full-scale engines for these types of fuels.  
5.5 This test determines ignition characteristics and requires a sample of approximately 100 mL and a test time of approximately 20 min on a fit-for-use instrument.
SCOPE
1.1 This automated laboratory test method covers the quantitative determination of the ignition characteristics of conventional diesel fuel oil, oil-sands based fuels, hydrocarbon oils, blends of fuel containing biodiesel material, diesel fuel oils containing cetane number improver additives, and is applicable to products typical of ASTM Specification D975 grades No. 1-D S15, No. 1-D S500, and No. 1-D S5000, and grades No. 2-D S15, No. 2-D S500, and No. 2-D S5000 diesel fuel oils, European standard EN 590, and Canadian standards CAN/CGSB-3.517 and 3.520. The test method may also be applied to the quantitative determination of the ignition characteristics of diesel fuel blending components.  
1.2 This test method measures the ignition delay of a diesel fuel injected directly into a constant volume combustion chamber containing heated, compressed air. An equation correlates an ignition delay determination to cetane number by Test Method D613, resulting in a derived cetane number (DCN).  
1.3 This test method covers the ignition delay range from 2.64 ms to 6.90 ms (75.1 DCN to 31.5 DCN). The combustion analyzer can measure shorter and longer ignition delays, but precision may be affected. For these shorter or longer ignition delays the correlation equation for DCN is given in Appendix X2.  
1.4 For purposes of determining conformance with the parameters of this test method, an observed value or a calculated value shall be rounded “to the nearest unit” in the last right-hand digit used in expressing the parameter, in accordance with the rounding method of Practice E29.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Nov-2022
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• ICS: 43.060.40 - Fuel systems
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.01 - Combustion Characteristics

Relations

• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D6708-24 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Mar-2024
• Refers: ASTM D613-24 - Standard Test Method for Cetane Number of Diesel Fuel Oil
• Effective Date: 01-Feb-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D975-23a - Standard Specification for Diesel Fuel
• Effective Date: 15-Dec-2023
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM D6708-19 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-May-2019
• Refers: ASTM D975-19 - Standard Specification for Diesel Fuel Oils
• Effective Date: 01-Feb-2019
• Refers: ASTM D975-18a - Standard Specification for Diesel Fuel Oils
• Effective Date: 01-Dec-2018
• Refers: ASTM D6708-18 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-2018
• Refers: ASTM D975-17a - Standard Specification for Diesel Fuel Oils
• Effective Date: 15-Dec-2017

Overview

ASTM D6890-22: Standard Test Method for Determination of Ignition Delay and Derived Cetane Number (DCN) of Diesel Fuel Oils by Combustion in a Constant Volume Chamber is an internationally recognized laboratory test method published by ASTM International. This standard provides a quantitative procedure for determining the ignition characteristics of diesel fuel oils-including conventional diesel, oil-sands-based fuels, hydrocarbon oils, and blends containing biodiesel materials-by measuring ignition delay (ID) and calculating the derived cetane number (DCN) using a combustion analyzer operating in a constant volume chamber.

The DCN value is an important indicator of the ignition quality of diesel fuels used in compression ignition engines. The method is widely accepted for specification, quality control, and research in the fuel and engine industries, and helps users understand fuel performance under controlled laboratory conditions.

Key Topics

• Ignition Delay (ID): Time elapsed (in milliseconds) between the start of fuel injection and the start of combustion, as measured within a strictly controlled combustion chamber. ID serves as a direct measure of a fuel's ignition characteristic.

• Derived Cetane Number (DCN): A value calculated from the ignition delay, correlated to the cetane number as determined by reference engine methods such as ASTM D613. DCN is used to express the ignition quality of diesel fuels in a manner consistent with established industry metrics.

• Applicability: The test accommodates a broad range of diesel products, including:

  • ASTM D975 No. 1-D and No. 2-D grades (S15, S500, S5000)
  • European EN 590-compliant fuels
  • Canadian CAN/CGSB-3.517 and 3.520 fuels
  • Diesel blends containing biodiesel and cetane number improvers

• Automation & Efficiency: The method uses an automated analyzer that offers fast, repeatable results with minimal operator intervention-reducing analysis time and improving laboratory throughput.

• Sample & Precision: Approximately 100 mL of sample is required, with a typical analysis time of 20 minutes. The method offers defined repeatability and reproducibility, supporting reliable comparison among laboratories.

Applications

ASTM D6890-22 is essential for multiple practical applications in the fuel and engine industries:

• Fuel Specification and Quality Assurance: Enables accurate, objective comparison of diesel fuel ignition properties, aiding suppliers and regulators in verifying compliance with industry and national standards.
• Engine and Fuel Development: Assists engine manufacturers and fuel formulators in optimizing the match between engines and fuels, supporting the design of high-performance, efficient engines for various operating conditions.
• Research: Valuable for investigating the ignition behavior of new or alternative fuels, including the evaluation of biofuels and synthetic diesel components where the relationship to full-scale engine performance needs careful consideration.
• Blending Component Assessment: Supports evaluation of blending components for compatibility and quality control prior to integration into finished diesel fuels.

Related Standards

• ASTM D613: Test Method for Cetane Number of Diesel Fuel Oil - the reference engine method for cetane number determination.
• ASTM D975: Specification for Diesel Fuel Oils - covers fuel requirements for on- and off-road applications.
• EN 590: European standard for automotive diesel fuel.
• CAN/CGSB-3.517 and 3.520: Canadian specifications for diesel fuel and diesel/biodiesel blends.
• ISO 4259: Petroleum products-Determination and application of precision data in relation to methods of test.
• ASTM D4057, D4177: Practices for manual and automatic sampling of petroleum products.
• ASTM D6299: Practice for applying statistical quality assurance and control charting techniques in laboratories.

ASTM D6890-22 is an indispensable test method for stakeholders in fuel formulation, distribution, and engine manufacturing, ensuring reliable assessment of diesel fuel ignition quality and harmonization with global industry practices.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6890 − 22
Standard Test Method for
Determination of Ignition Delay and Derived Cetane Number
(DCN) of Diesel Fuel Oils by Combustion in a Constant
1,2
Volume Chamber
This standard is issued under the fixed designation D6890; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This automated laboratory test method covers the quan-
standard.
titative determination of the ignition characteristics of conven-
1.6 This standard does not purport to address all of the
tional diesel fuel oil, oil-sands based fuels, hydrocarbon oils,
safety concerns, if any, associated with its use. It is the
blends of fuel containing biodiesel material, diesel fuel oils
responsibility of the user of this standard to establish appro-
containingcetanenumberimproveradditives,andisapplicable
priate safety, health, and environmental practices and deter-
to products typical of ASTM Specification D975 grades No.
mine the applicability of regulatory limitations prior to use.
1-D S15, No. 1-D S500, and No. 1-D S5000, and grades No.
1.7 This international standard was developed in accor-
2-D S15, No. 2-D S500, and No. 2-D S5000 diesel fuel oils,
dance with internationally recognized principles on standard-
European standard EN 590, and Canadian standards CAN/
ization established in the Decision on Principles for the
CGSB-3.517 and 3.520. The test method may also be applied
Development of International Standards, Guides and Recom-
to the quantitative determination of the ignition characteristics
mendations issued by the World Trade Organization Technical
of diesel fuel blending components.
Barriers to Trade (TBT) Committee.
1.2 This test method measures the ignition delay of a diesel
fuel injected directly into a constant volume combustion
2. Referenced Documents
chamber containing heated, compressed air. An equation cor-
2.1 ASTM Standards:
relates an ignition delay determination to cetane number by
D613Test Method for Cetane Number of Diesel Fuel Oil
Test Method D613, resulting in a derived cetane number
D975Specification for Diesel Fuel
(DCN).
D1193Specification for Reagent Water
1.3 This test method covers the ignition delay range from
D4057Practice for Manual Sampling of Petroleum and
2.64msto 6.90ms (75.1DCN to 31.5 DCN). The combustion
Petroleum Products
analyzer can measure shorter and longer ignition delays, but
D4175Terminology Relating to Petroleum Products, Liquid
precision may be affected. For these shorter or longer ignition
Fuels, and Lubricants
delays the correlation equation for DCN is given in Appendix
D4177Practice for Automatic Sampling of Petroleum and
X2.
Petroleum Products
1.4 For purposes of determining conformance with the D5854Practice for Mixing and Handling of Liquid Samples
parameters of this test method, an observed value or a
of Petroleum and Petroleum Products
calculated value shall be rounded “to the nearest unit” in the D6299Practice for Applying Statistical Quality Assurance
last right-hand digit used in expressing the parameter, in
and Control Charting Techniques to Evaluate Analytical
accordance with the rounding method of Practice E29. Measurement System Performance
D6300Practice for Determination of Precision and Bias
Data for Use in Test Methods for Petroleum Products,
This test method is under the jurisdiction of ASTM Committee D02 on Liquid Fuels, and Lubricants
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
D6708Practice for StatisticalAssessment and Improvement
Subcommittee D02.01 on Combustion Characteristics.
of Expected Agreement Between Two Test Methods that
Current edition approved Nov. 15, 2022. Published December 2022. Originally
approved in 2003. Last previous edition approved in 2021 as D6890–21. DOI:
10.1520/D6890-22.
2 3
This test method is based on IP PM CQ/2001, published in the IP Standard For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Methods for Analysis and Testing of Petroleum and Related Products and British contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standard 2000 Parts. Copyrighted by Energy Institute, 61 New Cavendish Street, Standards volume information, refer to the standard’s Document Summary page on
London, W1G 7AR, UK. Adapted with permission of Energy Institute. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6890 − 22
Purport to Measure the Same Property of a Material 3.1.5 check standard, n—in QC testing, material having an
E29Practice for Using Significant Digits in Test Data to accepted reference value used to determine the accuracy of a
Determine Conformance with Specifications measurement system. D6299
E456Terminology Relating to Quality and Statistics
3.1.5.1 Discussion—In the context of this test method,
check standard refers to heptane.
2.2 ISO Standards:
ISO 4010Diesel Engines—Calibrating Nozzle, Delay Pintle
3.1.6 hydrocarbon oil, n—a homogeneous mixture with
Type
elemental composition primarily of carbon and hydrogen that
ISO 4259Petroleum products—Determination and applica-
may also contain sulfur, oxygen, or nitrogen from residual
tion of precision data in relation to methods of test
impurities and contaminants associated with the fuel’s raw
materials and manufacturing processes and excluding added
2.3 EN Standard:
oxygenated materials.
EN590AutomotiveFuels—Diesel—RequirementsandTest
Methods
3.1.6.1 Discussion—Neithermacronormicroemulsionsare
2.4 Energy Institute Standard:
included in this definition since neither are homogeneous
IP 41Ignition Quality of Diesel Fuels—Cetane Engine Test
mixtures.
Method
3.1.6.2 Discussion—Examples of excluded oxygenated ma-
2.5 Canadian Standards: terials are alcohols, esters, ethers, and triglycerides.
CAN/CGSB-3.517 Diesel Fuel 3.1.6.3 Discussion—The hydrocarbon oil may be manufac-
CAN/CGSB 3.520Diesel Fuel Containing Low Levels of
tured from a variety of raw materials, for example petroleum
Biodiesel (B1–B5) (crude oil), oil sands, natural gas, coal, and biomass.
3.1.7 quality control (QC) sample, n—for use in quality
3. Terminology
assuranceprogramstodetermineandmonitortheprecisionand
stability of a measurement system, a stable and homogeneous
3.1 Definitions:
material having physical or chemical properties, or both,
3.1.1 accepted reference value (ARV), n—value that serves
similar to those of typical samples tested by the analytical
asanagreed-uponreferenceforcomparisonandthatisderived
measurement system.The material is properly stored to ensure
as (1) a theoretical or established value, based on scientific
sample integrity, and is available in sufficient quantity for
principles, (2) an assigned value, based on experimental work
repeated, long term testing. D6299
ofsomenationalorinternationalorganization,suchastheU.S.
National Institute of Standards and Technology (NIST), or (3)
3.2 Definitions of Terms Specific to This Standard:
a consensus value, based on collaborative experimental work
3.2.1 calibration reference material, n—pure chemical hav-
under the auspices of a scientific or engineering group. E456
ing an assigned ignition delay accepted reference value.
3.1.1.1 Discussion—In the context of this test method,
3.2.2 charge air, n—compressed air at a specified pressure
accepted reference value is understood to apply to the ignition
introducedtothecombustionchamberatthebeginningofeach
delay of specific reference materials determined under repro-
test cycle.
ducibility conditions by collaborative experimental work.
3.2.3 charge air temperature, n—temperature, in °C, of the
3.1.2 biodiesel, n—fuel comprised of mono-alkyl esters of
air inside the combustion chamber.
long chain fatty acids derived from vegetable oils or animal
fats, designated B100.
3.2.4 combustion analyzer, n—integrated compression igni-
tion apparatus to measure the ignition characteristics of diesel
3.1.3 biodiesel blend (BXX), n—a homogeneous mixture of
fuel oil.
hydrocarbon oils and mono alkyl esters of long chain fatty
acids.
3.2.5 derived cetane number (DCN), n—a number calcu-
3.1.3.1 Discussion—In the abbreviation, BXX, the XX rep-
lated using a conversion equation to determine a cetane
resents the volume percentage of biodiesel fuel in the blend.
number.
3.1.4 cetane number (CN), n—a measure of the ignition
3.2.5.1 Discussion—Theconversionequationrelatesamea-
performance of a diesel fuel oil obtained by comparing it to
sured ignition delay or ignition delay and combustion delay
reference fuels in a standardized engine test. D4175 from a combustion analyzer to a cetane number.
3.1.4.1 Discussion—In the context of this test method,
3.2.6 ignition delay (ID), n—that period of time, in milli-
cetane number is that defined by Test Method D613/IP 41.
seconds(ms),betweenthestartoffuelinjectionandthestartof
combustion as determined using the specific combustion ana-
lyzer applicable for this test method.
AvailablefromAmericanNationalStandardsInstitute,25W.43rdSt.,4thfloor,
3.2.6.1 Discussion—In the context of this test method, start
New York, NY 10036.
5 offuelinjectionisinterpretedastheinitialmovementorliftof
Available from European Committee for Standardization. Central Secretariat:
theinjectornozzleneedleasmeasuredbyamotionsensor;start
rue de Stassart, 36, B-1050 Brussels, Belgium.
Available from Institute of Petroleum, 61 New Cavendish St., London, W1G
of combustion is interpreted as that point in the combustion
7AR, U.K.
cycle when a significant and sustained increase in rate-of-
Available from Canadian General Standards Board (CGSB), 11 Laurier St.,
change in pressure, as measured by a pressure sensor in the
PhaseIII,PlaceduPortage,Gatineau,QuebecK1A0S5,Canada,http://www.tpsgc-
pwgsc.gc.ca/ongc-cgsb. combustion chamber, ensures combustion is in progress.
D6890 − 22
NOTE 1—The formation of peroxide and radicals can effect ignition
3.2.7 operating period, n—the time, not to exceed 12 h,
delay measurement. These formations are minimized when the sample or
between successive calibration or QC testing, or both, of the
material is stored in the dark in a cold room at a temperature of less than
combustion analyzer by a single operator.
10°C, and covered by a blanket of nitrogen.
3.3 Abbreviations:
6.2 Statistical analysis of data from a sequential testing
3.3.1 ARV—accepted reference value.
study (Note 2) revealed a possible carryover effect in succeed-
3.3.2 CN—cetane number. ing tests on samples containing 2–ethylhexylnitrate cetane
improver at concentrations above 2000 ppm.
3.3.3 DCN—derived cetane number.
NOTE2—Inthesequentialtestingstudy,afuelwithoutcetaneimprover
3.3.4 ID—ignition delay.
was tested three times back-to-back. Then a fuel with 2–ethylhexylnitrate
3.3.5 QC—quality control.
cetane improver at concentrations above 2000 ppm was tested.
Subsequently, the same fuel without cetane improver was tested three
4. Summary of Test Method
times. Statistical analyses of repeat data on two units were examined for
evidence of hysteresis.
4.1 A small specimen of diesel fuel oil is injected into a
heated, temperature-controlled constant volume chamber,
7. Apparatus
which has previously been charged with compressed air. Each
7.1 General—Thistestmethodusesanintegratedautomated
injectionproducesasingle-shot,compressionignitioncombus-
analytical measurement system comprised of: (1) a constant
tion cycle. ID is measured using sensors that detect the start of
volume compression ignition combustion chamber with exter-
fuel injection and the start of significant combustion for each
nal electrical heating elements, suitable insulation and pneu-
cycle. A complete sequence comprises 15 preliminary cycles
matically actuated intake and exhaust valves, (2) a heated,
and 32 further cycles. The ID measurements for the last 32
pneumatically actuated fuel injection system with pump,
cycles are averaged to produce the ID result. An equation
injector nozzle assembly, and associated sample reservoir, (3)
converts the ID result to DCN (derived cetane number), which
a coolant system with a liquid-to-air heat exchanger, filter,
is correlated to cetane number by Test Method D613.
circulating pump and flow control valves, (4) temperature
5. Significance and Use
thermocouples, pressure gages and sensors, an injector nozzle
needle motion sensor, compressed gas pressure regulators,
5.1 The ID and DCN values determined by this test method
control valves, pneumatic actuator components, and solenoid
can provide a measure of the ignition characteristics of diesel
valves, and (5) a computer to control test sequencing, acquire
fuel oil in compression ignition engines.
and accumulate sensor signal data, provide processing
5.2 This test can be used in commerce as a specification aid
calculations, and automatically output a printed report of some
to relate or match fuels and engines. It can also be useful in
important test parameters (see Fig. 1).
research or when there is interest in the ignition delay of a
7.2 See Annex A2, Combustion Analyzer Equipment De-
diesel fuel under the conditions of this test method.
scription and Specifications, for detailed information.
5.3 The relationship of diesel fuel oil DCN determinations
7.3 Compressed Gas Pressure Regulators:
to the performance of full-scale, variable-speed, variable-load
7.3.1 ChargeAirRegulator,atwo-stageregulatorcapableof
diesel engines is not completely understood.
controllingthedownstreampressuretoaminimumpressureof
5.4 This test may be applied to non-conventional fuels. It is
2.2 MPa.
recognized that the performance of non-conventional fuels in
7.3.2 Actuator Utility Compressed Air Regulator, a two-
full-scale engines is not completely understood. The user is
stageregulatorcapableofcontrollingthedownstreampressure
therefore cautioned to investigate the suitability of ignition
to a minimum pressure of 1.3 MPa.
characteristic measurements for predicting performance in
7.3.3 Fuel Reservoir Utility Compressed Nitrogen
full-scale engines for these types of fuels.
Regulator, a single or two-stage regulator capable of control-
5.5 Thistestdeterminesignitioncharacteristicsandrequires
ling the downstream pressure to a minimum pressure of
a sample of approximately 100 mL and a test time of
350.kPa.
approximately 20 min on a fit-for-use instrument.
7.4 Auxiliary Apparatus:
7.4.1 Diesel Fuel Oil Sample Filter, a single-use glass fiber,
6. Interferences
polytetrafluorethylene (PTFE), or nylon filter with a nominal
6.1 Minimize exposure of sample fuels, calibration refer-
ence materials, QC samples, and check standard to sunlight or
fluorescent lamp UV emissions to minimize induced chemical
The sole source of supply of the combustion analyzer known to the committee
at this time is CFR Engines Canada ULC, 17 Fitzgerald Road, Suite 102, Ottawa,
reactions that can affect ignition delay measurements.
Canada, K2H 9G1. If you are aware of alternative suppliers, please provide this
6.1.1 Exposure of these fuels and materials to UV wave-
information to ASTM International Headquarters. Your comments will receive
lengths shorter than 550 nanometers for a short period of time 1
careful consideration at a meeting of the responsible technical committee, which
may significantly affect ignition delay measurements. you may attend.
The fuel injection system is covered by a patent. Interested parties are invited
to submit information regarding the identification of an alternative(s) to this
Supporting data have been filed atASTM International Headquarters and may patenteditemtotheASTMInternationalHeadquarters.Yourcommentswillreceive
beobtainedbyrequestingResearchReportRR:D02-1502.ContactASTMCustomer careful consideration at a meeting of the responsible technical committee, which
Service at [e-mail]. you may attend.
D6890 − 22
FIG. 1 Combustion Analyzer Schematic
pore size of 3µm to 5µm for use with a positive pressure 8.1.2 Methylcyclohexane (MCH),withaminimumpurityof
delivery device such as a glass syringe or glass-lined metal 99.0% by volume. The assigned ID for this material is
ARV
syringe. 10.4ms. (Warning—Flammable. Vapor harmful. Vapor may
cause flash fire.)
7.4.2 Positive Pressure Delivery Device, a non-reactive
positive pressure delivery device such as a glass syringe or a
NOTE 3—Experience has found some MCH meeting the purity speci-
glass-lined metal syringe.
fication but which does not meet Ignition Delay (typically 1millisec-
ARV
ond to 1.5milliseconds shorter). It is recommended that new material be
8. Reagents and Materials qualified prior to use.
8.1 Calibration Reference Materials: 8.2 Check Standard:
8.2.1 Heptane (n-heptane), with a minimum purity of
8.1.1 Heptane (n-heptane), with a minimum purity of
99.5% by volume. The assigned ID for this material is 99.5% by volume. The assigned ID for this material is
ARV ARV
3.78ms. (Warning—Flammable. Vapor harmful. Vapor may
3.78ms. (Warning—Flammable. Vapor harmful. Vapor may
cause flash fire.) cause flash fire.)
D6890 − 22
8.3 Quality Control Sample, a stable and homogeneous settingaseriesoftestingvariablestoprescribedspecifications.
diesel fuel oil having physical and chemical properties similar Some of these settings are established by component
to those of typical sample fuels routinely tested. (Warning— specifications, others are operating conditions that are
Combustible. Vapor harmful.) monitored/controlled by the computer software or by operator
adjustment.
8.4 ChargeAir,compressedaircontaining19.9%to21.9%
byvolumeoxygen,lessthan0.003%byvolumehydrocarbons, 10.3 Settings Based on Component Specifications:
and less than 0.025% by volume water. For charge air 10.3.1 Injector Nozzle Opening Pressure—Each time the
cylinders supplied with a blend of oxygen and nitrogen, it is nozzle assembly is reassembled or replaced, or both, set the
required that a quality control test be performed after an air pressure-adjusting nut to release fuel in conformance with the
cylinderhasbeenchanged.(Warning—Compressedgasunder requirements in the manufacturer’s equipment manual, using
high pressure that supports combustion.) an injector nozzle tester. For additional details, refer to the
instruction manual of the manufacturer.
8.5 Coolant System Fluid, a 50:50 volume mixture of water
10.3.2 Injector Nozzle Motion Sensor Position—Manually
andcommercialethyleneglycol-basedantifreeze.(Warning—
position the motion sensor while visually observing the nozzle
Poison. May be harmful or fatal if inhaled or swallowed.)
needle movement signal on the computer monitor (see Fig.
8.5.1 Antifreeze, commercial automotive cooling system
A4.1). The criteria for optimized setting are as follows:
ethylene glycol-based solution.
10.3.2.1 The signal prior to the steep increase in needle lift
8.5.2 Water,distilledorreagent-grade,conformingtoSpeci-
is required to indicate some signal noise. If the signal trace is
fication D1193, Type IV.
flat and constant, the motion sensor is too far away from the
8.6 Actuator Utility Compressed Air,oilfreecompressedair
nozzle needle extension pin.
havinglessthan0.1%byvolumewatersuppliedataminimum
10.3.2.2 The peak of the steep increase in signal level is
sustained pressure of 1.5 MPa. (Warning—Compressed gas
required to be visible on the computer monitor screen. If the
under high pressure that supports combustion.)
signal peak is flat, the motion sensor is too close to the nozzle
8.7 Fuel Reservoir Utility Compressed Nitrogen, com- needle extension pin. For additional details, refer to the
pressed nitrogen having a minimum purity of 99.9% by instruction manual of the manufacturer.
volume. (Warning—Compressed gas under high pressure.) 10.3.3 Injector Nozzle Coolant Passage Thermocouple
Position—Proper positioning of the thermocouple in the injec-
9. Sampling and Test Specimen Preparation
tor nozzle coolant passage is set by installing a compression
9.1 Sampling:
fitting nut and associated plastic ferrule on the stainless steel
9.1.1 Collect diesel fuel oil samples in accordance with
sheath of the thermocouple, using a specialized depth setting
Practices D4057 or D4177.
tool to establish the correct depth of penetration. Adjust the
9.1.1.1 Collect and store diesel fuel samples in a suitable
depthofpenetration(inaccordancewiththeinstructionmanual
container such as a dark brown bottle, a metal can, or a
of the manufacturer) by repositioning the plastic ferrule on the
minimally reactive plastic container to minimize exposure to
stainless steel sheath of the thermocouple and tightening the
UV emissions.
nut to a snug level of tightness. For additional details, refer to
9.1.2 Refer to Practice D5854 for appropriate information
the instruction manual of the manufacturer.
relating to the mixing and handling of diesel fuel oil samples.
10.3.4 Charge Air Thermocouple Position—Proper posi-
tioning of the thermocouple in the combustion chamber is set
9.2 Test Specimen Preparation:
byinstallingacompressionfittingnutandassociatedferruleon
9.2.1 Sample Fuel Temperature—Condition the diesel fuel
the stainless steel sheath of the thermocouple, crimping the
sample before opening the storage container, so that it is at
ferrule on the sheath using a specialized depth setting tool to
room temperature, typically 18°C to 32°C.
establish the correct depth of penetration. For additional
9.2.2 Filtration—Prepare a test specimen by filtering diesel
details, refer to the instruction manual of the manufacturer.
fuel oil of sufficient volume to complete the test method,
10.3.5 Rate of Decrease of Combustion Chamber Pressure,
including flushing, through a nominal 3µm to 5µm porosity
lessthan3.5kPa/s,asmeasuredduringthecheckofthesealing
filter element using a positive pressure delivery device such as
integrity of the combustion chamber (see A3.5).
a glass syringe or a glass-lined metal syringe.
9.2.2.1 Collect the specimen in a dark brown bottle, metal
10.4 Standard Operating Conditions:
can or minimally reactive plastic container.
10.4.1 Charge Air Pressure (P2), 2.130MPa to 2.144MPa.
10.4.2 Charge Air Temperature (T4), 515°C to 575°C.
10. Basic Apparatus Settings and Standard Operating
10.4.2.1 The difference in temperature (T4 − T4 )as
max min
Conditions
determined and recorded by the computer, shall be less than
10.1 Installation of the apparatus requires placement on a
2.5°C during a 32 combustion cycle measurement determina-
level floor and connection of all utilities. Engineering and
tion.
technical support for this function is required, and the user
10.4.3 Combustion Chamber Outer Surface Temperature
shallberesponsibletocomplywithalllocalandnationalcodes
(T1)—Initiallysetbythemanufacturer,thesurfacetemperature
and installation requirements.
is monitored and controlled by the computer. Operator adjust-
10.2 Operation of the combustion analyzer, associated ment of the controller set-point is required, in accordance with
equipment, instrumentation and computer system requires the calibration procedure.
D6890 − 22
10.4.4 Combustion Chamber Pressure Sensor Temperature 11.3.1.3 If the temperature controller set-point adjustment
(T3), 110.°C to 150.°C. from the previous setting, exceeds 64°C, a system malfunc-
10.4.4.1 The difference in temperature (T3 − T3 )as tion is suspected and diagnostic procedures to determine and
max min
determined and recorded by the computer, shall be less than remedy the problem are recommended. Refer to the instruc-
8.0°C during a 32 combustion cycle measurement determina- tions provided by the manufacturer.
tion.
NOTE 5—After a change of charge air cylinders that employ a blend of
10.4.5 Coolant Return Temperature (T7), 30.°C to 50.°C.
oxygen and nitrogen, a temperature controller set-point adjustment be-
10.4.6 Fuel Sample Reservoir Pressure (P5), 310.kPa to
yond4°Ccanaccommodatetheextremelimitsofthe19.9%to21.9%by
380.kPa.Visually check the gage reading, as this parameter is volume oxygen in the blend.
not recorded by the data acquisition system.
11.3.1.4 Afteratemperaturecontrollerset-pointadjustment,
10.4.7 Fuel Injection Pump Temperature (T2), 32°C to
wait at least 10. min before initiating a new calibration so that
38°C.
the combustion analyzer attains thermal equilibrium.
10.4.8 Injector Nozzle Coolant Passage Temperature (T6)—
11.3.1.5 To be an acceptable data set, each single result is
The maximum (T6 ) and minimum (T6 ) temperatures as
max min
required to be within 3.72ms to 3.84ms.
determined and recorded by the computer, shall be within
11.3.1.6 If any of the three results is outside the limits, a
46.0°C to 54.0°C during a 32 combustion cycle measurement
system malfunction is suspected and diagnostic procedures to
determination.
determine and remedy the problem are recommended before
10.4.9 Injection Actuator Air Pressure (P3), 1.18MPa to
performing a new calibration. Refer to the instructions pro-
1.24MPa.
vided by the manufacturer.
10.4.10 Inlet/Exhaust Valve Actuator Air Pressure (P4),
11.3.2 Methylcyclohexane Calibration Reference
445kPa to 515kPa. Visually check the gage reading, as this
Material—Perform two consecutive ignition delay determina-
parameter is not recorded by the data acquisition system.
tions.
11. Calibration and Quality Control Testing 11.3.2.1 To be an acceptable data set, each single result is
required to be within 9.8ms to 11.0ms and the average of the
11.1 Calibration—Calibrate the combustion analyzer for
two results is required to be within 9.9ms to 10.9ms.
only the following reasons: (1) after it is installed and
11.3.2.2 If either of the two single results or the average of
commissioned, (2) after replacement of critical parts or com-
the two results is outside the respective limits, system perfor-
ponents of combustion chamber assembly (see A2.2), fuel
mance is unacceptable and it is recommended that diagnostic
injection system (see A2.3) or instrument sensors (see A2.4),
procedures be used to determine and remedy the problem
(3) after calibration of the data acquisition board, injection
before performing a new calibration. Refer to the instructions
actuator air pressure sensor or charge air pressure sensor, (4)
provided by the manufacturer.
whenever check standard or QC sample determinations are not
11.3.3 The combustion analyzer calibration is complete
in statistical control as determined by Practice D6299 or
when both heptane and methylcyclohexane data sets are
equivalent and the assignable causes for QC non-compliance
acceptable.
have been suitably addressed.
11.4 Quality Control (QC Testing)—Conduct a regular sta-
11.2 Precalibration Procedures:
tistical quality assurance (quality control) program in accor-
11.2.1 Clean the combustion chamber pressure sensor as-
dance with the techniques of Practice D6299 or equivalent.
sembly (see A3.3 and A3.4).
11.4.1 This test method requires quality control testing at
11.2.2 If necessary, start and warm-up the combustion
the beginning of each operating period by a single ignition
analyzer (see A3.1).
delay determination for both the check standard (heptane) and
11.3 Calibration Procedure—Two filtered calibration refer-
one QC sample.
ence materials are tested: (1) heptane to affirm that the
11.4.2 The QC sample is a typical diesel fuel oil having an
combustion chamber charge air temperature setting produces
ignition delay that represents the primary range of use for the
ignition delay measurements for this material that are within
combustion analyzer.
specification limits and, (2) methylcyclohexane to affirm that
11.4.2.1 If the combustion analyzer is used for testing fuels
the measurement sensitivity of the combustion analyzer pro-
having a very wide range of ignition delay, it may be useful to
duces ignition delay measurements for this material that are
have a second QC sample of a different ignition delay.
within specification limits.
11.4.3 For locations using blends of oxygen and nitrogen as
11.3.1 Heptane Calibration Reference Material—Perform
the source for charge air, conduct a QC test whenever there is
three consecutive ignition delay determinations.
a change from one cylinder to another.
11.3.1.1 The average of three acceptable ID results is
required to be within 3.77ms to 3.79ms.
NOTE 6—The oxygen content of the new oxygen and nitrogen blend
11.3.1.2 If the average ID is outside the limits, the combus- may differ from that of the previous source and can have a significant
effect on ID measurements.
tion chamber outer surface temperature controller set-point
requires adjustment to cause a change in the combustion
11.5 Check Standard—Perform a single ignition delay de-
chamber charge air temperature.
termination for filtered heptane.
11.5.1 This determination is acceptable if it satisfies the
NOTE 4—ID increases when the combustion chamber outer surface
temperature decreases and vice versa. limits protocol specified in Practice D6299 or equivalent.
D6890 − 22
11.5.2 Prior to having established ignition delay tolerances 13. Calculation
for heptane in accordance with Practice D6299 or equivalent,
13.1 Calculate the derived cetane number, DCN, from
use warning limits of 60.07 ms and action limits of
averageignitiondelay,ID(ms),recordedasin12.2.6usingEq
60.106ms, based on the average of the three acceptable ID
1:
results for heptane, as per 11.3.1.
DCN 54.4601186.6/ID (1)
NOTE7—Thewarningandactionlimitsforheptaneweredeterminedby NOTE 8—Eq 1 is the same as found in D6890 –16.
analysis of round robin test data.
13.2 Record the DCN to the nearest 0.1.
11.6 QC Sample—Perform a single ignition delay determi-
13.3 ThederivationandmaintenanceofEq1isdescribedin
nation for the filtered QC sample.
Annex A5.
11.6.1 This determination is acceptable if it satisfies the
limits protocol specified in Practice D6299 or equivalent.
14. Report
11.7 The combustion analyzer is fit-for-use when both the 14.1 Report the following information:
14.1.1 A reference to this standard,
check standard (heptane) and the QC sample ignition delay
determinations are acceptable. If the ignition delay determina- 14.1.2 The sample identification,
14.1.3 The date of the test,
tion for either material is not acceptable, conduct a new
calibrationbeforeperformingfurtherignitiondelaydetermina- 14.1.4 The ID result to the nearest hundredth (0.01 ms),
tions. 14.1.5 The DCN result to the nearest tenth (0.1),
14.1.6 The test’s average charge air temperature to the
nearest tenth (0.1) °C, and
12. Procedure
14.1.7 Any deviation, by agreement or otherwise, from the
12.1 Operating Period Procedure:
specified procedures.
12.1.1 If necessary, warm-up the combustion analyzer (see
A3.1).
15. Precision and Bias
12.1.2 Check the sealing integrity of the combustion cham-
15.1 General—The precision statements for ID and DCN
ber (see A3.5).
are based on interlaboratory results reported to the Energy
12.1.3 Check that the combustion analyzer is fit-for use by
Institute (EI) in their monthly diesel exchanges between
performing a quality control test (see 11.4).
October 2010 and January 2012 and on data reported to the
ASTM National Exchange Group (NEG) program from Sep-
12.2 Test Procedure:
tember2010throughSeptember2017.Thetestresultsforthese
12.2.1 Filter the diesel fuel sample at room temperature,
studies were statistically analyzed using ASTM Practice
using a non-reactive positive pressure delivery device such as
D6300/ISO 4259 techniques and involved 44 laboratories and
aglasssyringeorglass-linedmetalsyringeandsingle-usefilter
100 test samples from EI and NEG combined. The totality of
element, to prepare a test specimen of sufficient volume to
samplescoveredtheDCNrangefrom31.5DCNto75.1DCN,
complete the test method, including flushing. The recom-
and ID range from 6.90ms to 2.64 ms.
mended volume for most test purposes is 100 mL. See the
instructions provided by the manufacturer for further informa-
NOTE9—TheDCNanditsprecisionhavebeencalculatedfromignition
delay results using Eq 1.
tion.
NOTE 10—The precision statements for ID and DCN found in D6890
12.2.2 Flush, fill, and purge the fuel system with the
versions up to –16 are based on an interlaboratory study conducted in
specimen (see A3.2.2). 14
2002 (RR:D02-1602), supplemented by interlaboratory results reported
12.2.3 Initiate an automatic ignition delay determination to the ASTM National Exchange Group and the Energy Institute in their
monthlydieselexchangesbetweenJanuary2004andJuly2009(RR:D02-
using the appropriate computer command (see Annex A4 for
1700). The test results for the study were statistically analyzed using
detailed information about the test sequence).
ASTM Practice D6300/ISO 4259 techniques and involved, from the 2002
12.2.4 Check that all standard operating conditions are in
compliance.
12.2.5 If operating conditions are not in compliance, make Energy Institute test method research report number IP498 – RR2013.
Determination of Ignition Delay and Derived Cetane Number (DCN) of middle
the required adjustments and return to 12.2.2.
distillate fuels by combustion in a constant volume chamber, available from Energy
12.2.6 Record the average ignition delay to the nearest
Institute, 61 New Cavendish Street, London W1G 7AR, United Kingdom and
0.001ms for the calculation of the DCN (13.1). Energy Institute test method research report number IP498 – RR2013. Determina-
tion of Ignition Delay and Derived Cetane Number (DCN) of middle distillate fuels
12.3 Discharge unused specimen and clean the fuel system
by combustion in a constant volume chamber, available from Energy Institute, 61
New Cavendish Street, London W1G 7AR, United Kingdom.
(see A3.2.3 or A3.2.4) to prepare for (1) the next specimen
Supporting data have been filed atASTM International Headquarters and may
determination, or (2) combustion analyzer shut down (see
beobtainedbyrequestingResearchReportRR:D02-1897.ContactASTMCustomer
A3.6).
Service at [e-mail].
Supporting data have been filed atASTM International Headquarters and may
beobtainedbyrequestingResearchReportRR:D02-1602.ContactASTMCustomer
Service at [e-mail].
11 15
Supporting data have been filed atASTM International Headquarters and may Supporting data have been filed atASTM International Headquarters and may
beobtainedbyrequestingResearchReportRR:D02-1532.ContactASTMCustomer beobtainedbyrequestingResearchReportRR:D02-1700.ContactASTMCustomer
Service at [e-mail]. Service at [e-mail].
D6890 − 22
round robin, 10 laboratories and 15 test samples, and from the exchanges, TABLE 2 Repeatability and Reproducibility Values for Information
34 laboratories and 145 samples. The totality of samples covered the ID
ID (ms) Repeatability (r) Reproducibility (R)
rangefrom3.24msto6.24ms(DCNrangefrom62.0DCNto34.4DCN).
2.6 0.037 0.157
3.0 0.043 0.169
15.2 Precision:
3.5 0.050 0.184
15.2.1 Repeatability—The difference between successive
4.0 0.057 0.198
results obtained by the same operator with the same apparatus,
4.5 0.065 0.213
5.0 0.072 0.227
under constant operating conditions, on identical test materials
5.5 0.079 0.242
would, in the long run, in the normal and correct operation of
6.0 0.087 0.257
the test method, exceed the values calculated using the math-
6.5 0.094 0.271
6.9 0.100 0.283
ematical expressions in Table 1 only in one case in twenty.
DCN Repeatability (r) Reproducibility (R)
15.2.2 Reproducibility—The difference between two single
32 0.43 1.13
and independent results, obtained by different operators work-
35 0.47 1.32
ing in different laboratories on identical test materials, would,
40 0.53 1.63
in the long run, and in the normal and the correct operation of
45 0.59 1.94
50 0.65 2.25
the test method, exceed the values calculated using the math-
55 0.71 2.56
ematical expressions in Table 1 only in one case in twenty.
60 0.77 2.87
15.2.3 Examples of repeatability and reproducibility are
65 0.83 3.18
70 0.89 3.49
shown in Table 2 for user information.
75 0.95 3.80
15.3 Bias—TheIDdeterminedusingthistestmethodhasno
bias because ID is defined only in terms of this test method.
between a DCN result and the average of all non-outlying
15.4 Between-methods Bias (formerly called Relative Bias)
D613 results on the corresponding fuels) were computed. As
to Test Method D613—The degree of agreement of DCN
each fuel was measured by at least 31 D613 engines, their
results by this test method relative to CN results by Test
averages (or “Accepted Reference Values” or “D613 ARVs”)
Method D613 has been assessed in accordance with Practice
serve as a precise approximation to the long-term expected
D6708 using only those 45 of the precision samples (see 15.1)
D613 results.
for which at least 31 non-outlying engine results were submit-
15.4.2.2 The errors were divided by the corresponding
ted. The calculations presented below apply for DCN results
D613 ARVs to produce the individual Proportional Errors:
between34.5and56.5,andCNaveragesbyD613(D613ARV)
between 34.3 and 57.9 where CN average is computed as ProportionalError=~DCNresult 2 613 _ ARV!⁄D613_ARV (2)
described in 15.4.2.1.
No significant relationship between the variation of propor-
15.4.1 No bias correction considered in Practice D6708 can
tional errors and D613 ARV is apparent. Therefore it is
further improve the agreement between results from Test
reasonable to conclude that the proportional error behavior,
Method D6890 and Test Method D613.
while it is sample-specific, is in statistical control over the
15.4.1.1 Sample specific bias, as defined in PracticeD6708,
rangeofthefuelsstudied.Theproportionalerrorsareplottedin
was observed for some samples.
Fig. 2, along with their averages by sample and their 95%
15.4.1.2 The bias assessment outcome (B3) concludes that
quantile limits.
therearesample-specificbiasesthatdonotmeettheAnderson-
15.4.2.3 From the proportional errors in Fig. 2, fewer than
Darling test for normality in Practice D6708. This implies that
2.5% of the proportional errors exceeded 0.048, and fewer
the sample-specific biases cannot be reasonably modeled by a
than2.5%werelessthan–0.058.Thisimpliesthat,inthelong
Gaussian (normal) distribution. Users are cautioned that they
run, 19 of 20 DCN results can be expected to be between
may encounter non-Gaussian sample specific biases for some
94.2% and 104.8% of the D613ARV (expected cetane result
materials.
byD613)ofthatfuel.InactualCNunits,theselimitsare0.942
15.4.2 Proportional Error Limits for a Single DCN Result
× D613ARVto 1.048 × D613ARV. It is anticipated that these
Relative to a D613 ARV:
95% proportional error limits will remain valid so long as the
15.4.2.1 AsaD6708-compliantbetween-methodsreproduc-
biases continue to be in a state of statistical control. Fig. 3 is a
ibility cannot be calculated for non-Gaussian sample-specific
display of individual errors, with error limits expressed in
biases, quantile-based statistics were computed in accordance
actual CN units, as derived from the quantiles of the propor-
with D6299, subsection 6.2.2. From the 1047 non-outlying
tional errors.
DCNresultson45fuels,theindividual“errors”(thedifference
15.4.2.4 In Table 3, the proportional error limits calculated
fromtheaforementionedexchangedataareappliedtocompute
TABLE 1 Repeatability (r) and Reproducibility (R) for Ignition
95%limitsfortherangeofasingleconformingDCNresulton
Delay (ID) and Derived Cetane Number (DCN)
a fuel of a given D613_ARV, as computed in accordance with
ID (ms) DCN
D6299 as described above. In the long run, 19 times out of 20:
Repeatability (r) 0.01468 × (ID – 0.1) 0.01215 × (DCN + 3.5)
0.942 D613_ARV#DCN#1.048 D613_ARV (3)
Reproducibility (R) 0.02915 × (ID +2.8) 0.06201 × (DCN –13.7)
D6890 − 22
FIG. 2 Proportional Errors with Quantiles
FIG. 3 Error Limits from Proportional Error Quantiles
15.4.2.5 In Table 4, the proportional error limits calculated
fromtheaforementionedexchangedataareappliedtocompute
D6890 − 22
TABLE 3 95 % Error Limits in Cetane Units TABLE 4 95 % Prediction Limits for Expected D613 Result Calcu-
lated from the Proportional Error Limits
Expected D613 Result Lower Limit of Error of Upper Limit for Error of
Single DCN Result Single DCN Result
Single DCN Result Lower Prediction Limit for Upper Prediction Limit
34 –2.0 1.6
D613_ARV for D613_ARV
40 –2.3 1.9
34 32.4 36.1
45 –2.6 2.2
40 38.2 42.5
50 –2.9 2.4 45 42.9 47.8
55 –3.2 2.6
50 47.7 53.1
58 –3.4 2.8
55 52.5 58.4
58 55.4 61.6
95% limits for the range of a likely average D613 result of a
fuel, given a single DCN result. In the long run, 19 times out
of 20:
16. Keywords
0.954 DCN=DCN/1.048#D613_ARV#DCN/0.942=1.062DCN
16.1 cetane number; derived cetane number; diesel perfor-
(4) mance; ignition characteristic; ignition delay
ANNEXES
(Mandatory Information)
A1. HAZARDS INFORMATION
A1.1 Introduction A1.4.1 Applicable Substances:
A1.4.1.1 Ethylene glycol based antifreeze.
A1.1.1 Intheperformanceofthestandardtestmethodthere
are hazards to personnel. These are indicated in the text. For
A1.5 (Warning—Compressed gas under high pressure that
more detailed information regarding the hazards, refer to the
supports combustion.)
appropriateMaterialSafetyDataSheet(MSDS)foreachofthe
A1.5.1 Applicable Substances:
applicable substances to establish risks, proper handling, and
A1.5.1.1 Compressed air.
safety precautions.
A1.6 (Warning—Compressed gas under high pressure.)
A1.2 (Warning—Combustible. Vapor harmful.)
A1.6.1 Applicable Substances:
A1.2.1 Applicable Substances:
A1.6.1.1 Compressed nitrogen.
A1.2.1.1 Diesel fuel oil, and
A1.2.1.2 Quality control sample.
A1.7 (Warning—Hot surfaces.)
A1.3 (Warning—Flammable. Vapors harmful if inhaled. A1.7.1 Applicable Substances:
Vapors may cause flash fire.)
A1.7.1.1 Protective cage enclosing the combustion
chamber,
A1.3.1 Applicable Substances:
A1.7.1.2 Exposed areas of the combustion chamber around
A1.3.1.1 Heptane, and
the injector nozzle, and
A1.3.1.2 Methylcyclohexane.
A1.7.1.3 Exposedareasofthecombustionchambernearthe
A1.4 (Warning—Poison.Maybeharmfulorfatalifinhaled combustionchamberinsidethecombustionchamberprotective
or swallowed.) cage.
D6890 − 22
A2. COMBUSTION ANALYZER EQUIPMENT DESCRIPTION AND SPECIFICATIONS
A2.1 The combustion chamber assembly and fuel injection A2.2.6 Aseriesofwellsordrilledpassagestoaccommodate
system are critical to the proper operation of this test method. temperature sensor elements.
A2.2.7 An external insulation blanket to minimize heat loss
A2.2 Combustion Chamber Assembly—The principle com-
from the block and improve heat distribution inside the
ponentofthisassembly,illustratedinFig.A2.1,isacorrosion-
combustion chamber cavity.
protected metal cylindrical block that is precision machined
and fabricated to include the following features: A2.2.8 Aninletvalveassemblythatincludesadigitalsignal
controlled solenoid valve to operate a pneumatically actuated,
A2.2.1 A cavity along a central axis of the body, having a
servo-type valve connected to the inlet port.
volume of 0.211Lto 0.215L, that constitutes the compression
ignition combustion chamber. A2.2.9 An exhaust valve assembly that includes a digital
signal controlled solenoid valve to operate a pneumatically
A2.2.2 An opening at one end of the chamber to accommo-
actuated, servo-type valve connected to the exhaust port.
date insertion of the fuel injection nozzle assembly and which
includes a passage for circulation of liquid coolant to control A2.2.10 Combustion Chamber Heating Elements, nine
the injector nozzle temperature. cartridge-type resistance heaters.
A2.2.3 An opening at the other end of the chamber, to 10
A2.3 Fuel Injection System, a patented, integrated assem-
accommodate insertion of a pressure sensor liquid-cooled
bly of components for proper and repeatable injection of
housing.
calibrationreferencematerial,QCsamplefuel,checkstandard,
A2.2.4 Two drilled ports or pas
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6890 − 21 D6890 − 22
Standard Test Method for
Determination of Ignition Delay and Derived Cetane Number
(DCN) of Diesel Fuel Oils by Combustion in a Constant
1,2
Volume Chamber
This standard is issued under the fixed designation D6890; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This automated laboratory test method covers the quantitative determination of the ignition characteristics of conventional
diesel fuel oil, oil-sands based fuels, hydrocarbon oils, blends of fuel containing biodiesel material, diesel fuel oils containing
cetane number improver additives, and is applicable to products typical of ASTM Specification D975 grades No. 1-D S15, No.
1-D S500, and No. 1-D S5000, and grades No. 2-D S15, No. 2-D S500, and No. 2-D S5000 diesel fuel oils, European standard
EN 590, and Canadian standards CAN/CGSB-3.517 and 3.520. The test method may also be applied to the quantitative
determination of the ignition characteristics of diesel fuel blending components.
1.2 This test method measures the ignition delay of a diesel fuel injected directly into a constant volume combustion chamber
containing heated, compressed air. An equation correlates an ignition delay determination to cetane number by Test Method D613,
resulting in a derived cetane number (DCN).
1.3 This test method covers the ignition delay range from 2.64 ms to 6.90 ms (75.1 DCN to 31.5 DCN). The combustion analyzer
can measure shorter and longer ignition delays, but precision may be affected. For these shorter or longer ignition delays the
correlation equation for DCN is given in Appendix X2.
1.4 For purposes of determining conformance with the parameters of this test method, an observed value or a calculated value shall
be rounded “to the nearest unit” in the last right-hand digit used in expressing the parameter, in accordance with the rounding
method of Practice E29.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.01 on Combustion Characteristics.
Current edition approved July 1, 2021Nov. 15, 2022. Published July 2021December 2022. Originally approved in 2003. Last previous edition approved in 20182021 as
D6890 – 18.D6890 – 21. DOI: 10.1520/D6890-21.10.1520/D6890-22.
This test method is based on IP PM CQ/2001, published in the IP Standard Methods for Analysis and Testing of Petroleum and Related Products and British Standard
2000 Parts. Copyrighted by Energy Institute, 61 New Cavendish Street, London, W1G 7AR, UK. Adapted with permission of Energy Institute.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6890 − 22
2. Referenced Documents
2.1 ASTM Standards:
D613 Test Method for Cetane Number of Diesel Fuel Oil
D975 Specification for Diesel Fuel
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E456 Terminology Relating to Quality and Statistics
2.2 ISO Standards:
ISO 4010 Diesel Engines—Calibrating Nozzle, Delay Pintle Type
ISO 4259 Petroleum products—Determination and application of precision data in relation to methods of test
2.3 EN Standard:
EN 590 Automotive Fuels—Diesel—Requirements and Test Methods
2.4 Energy Institute Standard:
IP 41 Ignition Quality of Diesel Fuels—Cetane Engine Test Method
2.5 Canadian Standards:
CAN/CGSB-3.517 Diesel Fuel
CAN/CGSB 3.520 Diesel Fuel Containing Low Levels of Biodiesel (B1–B5)
3. Terminology
3.1 Definitions:
3.1.1 accepted reference value (ARV), n—value that serves as an agreed-upon reference for comparison and that is derived as (1)
a theoretical or established value, based on scientific principles, (2) an assigned value, based on experimental work of some
national or international organization, such as the U.S. National Institute of Standards and Technology (NIST), or (3) a consensus
value, based on collaborative experimental work under the auspices of a scientific or engineering group. E456
3.1.1.1 Discussion—
In the context of this test method, accepted reference value is understood to apply to the ignition delay of specific reference
materials determined under reproducibility conditions by collaborative experimental work.
3.1.2 biodiesel, n—fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,
designated B100.
3.1.3 biodiesel blend (BXX), n—blend of biodiesel fuel with diesel fuel oils.a homogeneous mixture of hydrocarbon oils and mono
alkyl esters of long chain fatty acids.
3.1.3.1 Discussion—
In the abbreviation, BXX, the XX represents the volume percentage of biodiesel fuel in the blend.
3.1.4 cetane number (CN), n—a measure of the ignition performance of a diesel fuel oil obtained by comparing it to reference fuels
in a standardized engine test. D4175
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute, 25 W. 43rd St., 4th floor, New York, NY 10036.
Available from European Committee for Standardization. Central Secretariat: rue de Stassart, 36, B-1050 Brussels, Belgium.
Available from Institute of Petroleum, 61 New Cavendish St., London, W1G 7AR, U.K.
Available from Canadian General Standards Board (CGSB), 11 Laurier St., Phase III, Place du Portage, Gatineau, Quebec K1A 0S5, Canada, http://www.tpsgc-
pwgsc.gc.ca/ongc-cgsb.
D6890 − 22
3.1.4.1 Discussion—
In the context of this test method, cetane number is that defined by Test Method D613/IP 41.
3.1.5 check standard, n—in QC testing, material having an accepted reference value used to determine the accuracy of a
measurement system. D6299
3.1.5.1 Discussion—
In the context of this test method, check standard refers to heptane.
3.1.6 hydrocarbon oil, n—a homogeneous mixture with elemental composition primarily of carbon and hydrogen that may also
contain sulfur, oxygen, or nitrogen from residual impurities and contaminants associated with the fuel’s raw materials and
manufacturing processes and excluding added oxygenated materials.
3.1.6.1 Discussion—
Neither macro nor micro emulsions are included in this definition since neither are homogeneous mixtures.
3.1.6.2 Discussion—
Examples of excluded oxygenated materials are alcohols, esters, ethers, and triglycerides.
3.1.6.3 Discussion—
The hydrocarbon oil may be manufactured from a variety of raw materials, for example petroleum (crude oil), oil sands, natural
gas, coal, and biomass.
3.1.7 quality control (QC) sample, n—for use in quality assurance programs to determine and monitor the precision and stability
of a measurement system, a stable and homogeneous material having physical or chemical properties, or both, similar to those of
typical samples tested by the analytical measurement system. The material is properly stored to ensure sample integrity, and is
available in sufficient quantity for repeated, long term testing. D6299
3.2 Definitions of Terms Specific to This Standard:
3.2.1 calibration reference material, n—pure chemical having an assigned ignition delay accepted reference value.
3.2.2 charge air, n—compressed air at a specified pressure introduced to the combustion chamber at the beginning of each test
cycle.
3.2.3 charge air temperature, n—temperature, in °C, of the air inside the combustion chamber.
3.2.4 combustion analyzer, n—integrated compression ignition apparatus to measure the ignition characteristics of diesel fuel oil.
3.2.5 derived cetane number (DCN), n—a number calculated using a conversion equation to determine a cetane number.
3.2.5.1 Discussion—
The conversion equation relates a measured ignition delay or ignition delay and combustion delay from a combustion analyzer to
a cetane number.
3.2.6 ignition delay (ID), n—that period of time, in milliseconds (ms), between the start of fuel injection and the start of
combustion as determined using the specific combustion analyzer applicable for this test method.
3.2.6.1 Discussion—
In the context of this test method, start of fuel injection is interpreted as the initial movement or lift of the injector nozzle needle
as measured by a motion sensor; start of combustion is interpreted as that point in the combustion cycle when a significant and
sustained increase in rate-of-change in pressure, as measured by a pressure sensor in the combustion chamber, ensures combustion
is in progress.
3.2.7 operating period, n—the time, not to exceed 12 h, between successive calibration or QC testing, or both, of the combustion
analyzer by a single operator.
3.3 Abbreviations:
3.3.1 ARV—accepted reference value.
3.3.2 CN—cetane number.
D6890 − 22
3.3.3 DCN—derived cetane number.
3.3.4 ID—ignition delay.
3.3.5 QC—quality control.
4. Summary of Test Method
4.1 A small specimen of diesel fuel oil is injected into a heated, temperature-controlled constant volume chamber, which has
previously been charged with compressed air. Each injection produces a single-shot, compression ignition combustion cycle. ID
is measured using sensors that detect the start of fuel injection and the start of significant combustion for each cycle. A complete
sequence comprises 15 preliminary cycles and 32 further cycles. The ID measurements for the last 32 cycles are averaged to
produce the ID result. An equation converts the ID result to DCN (derived cetane number), which is correlated to cetane number
by Test Method D613.
5. Significance and Use
5.1 The ID and DCN values determined by this test method can provide a measure of the ignition characteristics of diesel fuel
oil in compression ignition engines.
5.2 This test can be used in commerce as a specification aid to relate or match fuels and engines. It can also be useful in research
or when there is interest in the ignition delay of a diesel fuel under the conditions of this test method.
5.3 The relationship of diesel fuel oil DCN determinations to the performance of full-scale, variable-speed, variable-load diesel
engines is not completely understood.
5.4 This test may be applied to non-conventional fuels. It is recognized that the performance of non-conventional fuels in full-scale
engines is not completely understood. The user is therefore cautioned to investigate the suitability of ignition characteristic
measurements for predicting performance in full-scale engines for these types of fuels.
5.5 This test determines ignition characteristics and requires a sample of approximately 100 mL and a test time of approximately
20 min on a fit-for-use instrument.
6. Interferences
6.1 Minimize exposure of sample fuels, calibration reference materials, QC samples, and check standard to sunlight or fluorescent
lamp UV emissions to minimize induced chemical reactions that can affect ignition delay measurements.
6.1.1 Exposure of these fuels and materials to UV wavelengths shorter than 550 nanometers for a short period of time may
significantly affect ignition delay measurements.
NOTE 1—The formation of peroxide and radicals can effect ignition delay measurement. These formations are minimized when the sample or material
is stored in the dark in a cold room at a temperature of less than 10°C,10 °C, and covered by a blanket of nitrogen.
6.2 Statistical analysis of data from a sequential testing study (Note 2) revealed a possible carryover effect in succeeding tests on
samples containing 2–ethylhexylnitrate cetane improver at concentrations above 2000 ppm.
NOTE 2—In the sequential testing study, a fuel without cetane improver was tested three times back-to-back. Then a fuel with 2–ethylhexylnitrate cetane
improver at concentrations above 2000 ppm was tested. Subsequently, the same fuel without cetane improver was tested three times. Statistical analyses
of repeat data on two units were examined for evidence of hysteresis.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1502. Contact ASTM Customer
Service at [e-mail].
D6890 − 22
7. Apparatus
7.1 General—This test method uses an integrated automated analytical measurement system comprised of: (1) a constant volume
compression ignition combustion chamber with external electrical heating elements, suitable insulation and pneumatically actuated
intake and exhaust valves, (2) a heated, pneumatically actuated fuel injection system with pump, injector nozzle assembly, and
associated sample reservoir, (3) a coolant system with a liquid-to-air heat exchanger, filter, circulating pump and flow control
valves, (4) temperature thermocouples, pressure gages and sensors, an injector nozzle needle motion sensor, compressed gas
pressure regulators, control valves, pneumatic actuator components, and solenoid valves, and (5) a computer to control test
sequencing, acquire and accumulate sensor signal data, provide processing calculations, and automatically output a printed report
of some important test parameters (see Fig. 1).
FIG. 1 Combustion Analyzer Schematic
The sole source of supply of the combustion analyzer known to the committee at this time is CFR Engines Canada ULC, 17 Fitzgerald Road, Suite 102, Ottawa, Canada,
K2H 9G1. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration
at a meeting of the responsible technical committee, which you may attend.
The fuel injection system is covered by a patent. Interested parties are invited to submit information regarding the identification of an alternative(s) to this patented item
to the ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D6890 − 22
7.2 See Annex A2, Combustion Analyzer Equipment Description and Specifications, for detailed information.
7.3 Compressed Gas Pressure Regulators:
7.3.1 Charge Air Regulator, a two-stage regulator capable of controlling the downstream pressure to a minimum pressure of 2.2
MPa.
7.3.2 Actuator Utility Compressed Air Regulator, a two-stage regulator capable of controlling the downstream pressure to a
minimum pressure of 1.3 MPa.
7.3.3 Fuel Reservoir Utility Compressed Nitrogen Regulator, a single or two-stage regulator capable of controlling the downstream
pressure to a minimum pressure of 350. kPa.
7.4 Auxiliary Apparatus:
7.4.1 Diesel Fuel Oil Sample Filter, a single-use glass fiber, polytetrafluorethylene (PTFE), or nylon filter with a nominal pore size
of 3 μm to 5 μm for use with a positive pressure delivery device such as a glass syringe or glass-lined metal syringe.
7.4.2 Positive Pressure Delivery Device, a non-reactive positive pressure delivery device such as a glass syringe or a glass-lined
metal syringe.
8. Reagents and Materials
8.1 Calibration Reference Materials:
8.1.1 Heptane (n-heptane), with a minimum purity of 99.5 % by volume. The assigned ID for this material is 3.78 ms.
ARV
(Warning—WarningFlammable.—Flammable. Vapor harmful. Vapor may cause flash fire.)
8.1.2 Methylcyclohexane (MCH), with a minimum purity of 99.0 % by volume. The assigned ID for this material is 10.4 ms.
ARV
(Warning—WarningFlammable.—Flammable. Vapor harmful. Vapor may cause flash fire.)
NOTE 3—Experience has found some MCH meeting the purity specification but which does not meet Ignition Delay (typically 1 millisecond to
ARV
1.5 milliseconds shorter). It is recommended that new material be qualified prior to use.
8.2 Check Standard:
8.2.1 Heptane (n-heptane), with a minimum purity of 99.5 % by volume. The assigned ID for this material is 3.78 ms.
ARV
(Warning—WarningFlammable.—Flammable. Vapor harmful. Vapor may cause flash fire.)
8.3 Quality Control Sample, a stable and homogeneous diesel fuel oil having physical and chemical properties similar to those of
typical sample fuels routinely tested. (Warning—WarningCombustible.—Combustible. Vapor harmful.)
8.4 Charge Air, compressed air containing 19.9 % to 21.9 % by volume oxygen, less than 0.003 % by volume hydrocarbons, and
less than 0.025 % by volume water. For charge air cylinders supplied with a blend of oxygen and nitrogen, it is required that a
quality control test be performed after an air cylinder has been changed. (Warning—WarningCompressed—Compressed gas under
high pressure that supports combustion.)
8.5 Coolant System Fluid, a 50:50 volume mixture of water and commercial ethylene glycol-based antifreeze. (Warning—
WarningPoison.—Poison. May be harmful or fatal if inhaled or swallowed.)
8.5.1 Antifreeze, commercial automotive cooling system ethylene glycol-based solution.
8.5.2 Water, distilled or reagent-grade, conforming to Specification D1193, Type IV.
D6890 − 22
8.6 Actuator Utility Compressed Air, oil free compressed air having less than 0.1 % by volume water supplied at a minimum
sustained pressure of 1.5 MPa. (Warning—WarningCompressed—Compressed gas under high pressure that supports combustion.)
8.7 Fuel Reservoir Utility Compressed Nitrogen, compressed nitrogen having a minimum purity of 99.9 % by volume.
(Warning—WarningCompressed—Compressed gas under high pressure.)
9. Sampling and Test Specimen Preparation
9.1 Sampling:
9.1.1 Collect diesel fuel oil samples in accordance with Practices D4057 or D4177.
9.1.1.1 Collect and store diesel fuel samples in a suitable container such as a dark brown bottle, a metal can, or a minimally
reactive plastic container to minimize exposure to UV emissions.
9.1.2 Refer to Practice D5854 for appropriate information relating to the mixing and handling of diesel fuel oil samples.
9.2 Test Specimen Preparation:
9.2.1 Sample Fuel Temperature—Condition the diesel fuel sample before opening the storage container, so that it is at room
temperature, typically 18 °C to 32 °C.
9.2.2 Filtration—Prepare a test specimen by filtering diesel fuel oil of sufficient volume to complete the test method, including
flushing, through a nominal 3 μm to 5 μm porosity filter element using a positive pressure delivery device such as a glass syringe
or a glass-lined metal syringe.
9.2.2.1 Collect the specimen in a dark brown bottle, metal can or minimally reactive plastic container.
10. Basic Apparatus Settings and Standard Operating Conditions
10.1 Installation of the apparatus requires placement on a level floor and connection 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.
10.2 Operation of the combustion analyzer, associated equipment, instrumentation and computer system requires setting a series
of testing variables to prescribed specifications. Some of these settings are established by component specifications, others are
operating conditions that are monitored/controlled by the computer software or by operator adjustment.
10.3 Settings Based on Component Specifications:
10.3.1 Injector Nozzle Opening Pressure—Each time the nozzle assembly is reassembled or replaced, or both, set the
pressure-adjusting nut to release fuel in conformance with the requirements in the manufacturer’s equipment manual, using an
injector nozzle tester. For additional details, refer to the instruction manual of the manufacturer.
10.3.2 Injector Nozzle Motion Sensor Position—Manually position the motion sensor while visually observing the nozzle needle
movement signal on the computer monitor (see Fig. A4.1). The criteria for optimized setting are as follows:
10.3.2.1 The signal prior to the steep increase in needle lift is required to indicate some signal noise. If the signal trace is flat and
constant, the motion sensor is too far away from the nozzle needle extension pin.
10.3.2.2 The peak of the steep increase in signal level is required to be visible on the computer monitor screen. If the signal peak
is flat, the motion sensor is too close to the nozzle needle extension pin. For additional details, refer to the instruction manual of
the manufacturer.
10.3.3 Injector Nozzle Coolant Passage Thermocouple Position—Proper positioning of the thermocouple in the injector nozzle
coolant passage is set by installing a compression fitting nut and associated plastic ferrule on the stainless steel sheath of the
D6890 − 22
thermocouple, using a specialized depth setting tool to establish the correct depth of penetration. Adjust the depth of penetration
(in accordance with the instruction manual of the manufacturer) by repositioning the plastic ferrule on the stainless steel sheath
of the thermocouple and tightening the nut to a snug level of tightness. For additional details, refer to the instruction manual of
the manufacturer.
10.3.4 Charge Air Thermocouple Position—Proper positioning of the thermocouple in the combustion chamber is set by installing
a compression fitting nut and associated ferrule on the stainless steel sheath of the thermocouple, crimping the ferrule on the sheath
using a specialized depth setting tool to establish the correct depth of penetration. For additional details, refer to the instruction
manual of the manufacturer.
10.3.5 Rate of Decrease of Combustion Chamber Pressure, less than 3.5 kPa/s, as measured during the check of the sealing
integrity of the combustion chamber (see A3.5).
10.4 Standard Operating Conditions:
10.4.1 Charge Air Pressure (P2), 2.130 MPa to 2.144 MPa.
10.4.2 Charge Air Temperature (T4), 515 °C to 575 °C.
10.4.2.1 The difference in temperature (T4 − T4 ) as determined and recorded by the computer, shall be less than 2.5 °C
max min
during a 32 combustion cycle measurement determination.
10.4.3 Combustion Chamber Outer Surface Temperature (T1)—Initially set by the manufacturer, the surface temperature is
monitored and controlled by the computer. Operator adjustment of the controller set-point is required, in accordance with the
calibration procedure.
10.4.4 Combustion Chamber Pressure Sensor Temperature (T3), 110. °C to 150. °C.
10.4.4.1 The difference in temperature (T3 − T3 ) as determined and recorded by the computer, shall be less than 8.0 °C
max min
during a 32 combustion cycle measurement determination.
10.4.5 Coolant Return Temperature (T7), 30. °C to 50. °C.
10.4.6 Fuel Sample Reservoir Pressure (P5), 310. kPa to 380. kPa. Visually check the gage reading, as this parameter is not
recorded by the data acquisition system.
10.4.7 Fuel Injection Pump Temperature (T2), 32 °C to 38 °C.
10.4.8 Injector Nozzle Coolant Passage Temperature (T6)—The maximum (T6 ) and minimum (T6 ) temperatures as
max min
determined and recorded by the computer, shall be within 46.0 °C to 54.0 °C during a 32 combustion cycle measurement
determination.
10.4.9 Injection Actuator Air Pressure (P3), 1.18 MPa to 1.24 MPa.
10.4.10 Inlet/Exhaust Valve Actuator Air Pressure (P4), 445 kPa to 515 kPa. Visually check the gage reading, as this parameter
is not recorded by the data acquisition system.
11. Calibration and Quality Control Testing
11.1 Calibration—Calibrate the combustion analyzer for only the following reasons: (1) after it is installed and commissioned, (2)
after replacement of critical parts or components of combustion chamber assembly (see A2.2), fuel injection system (see A2.3) or
instrument sensors (see A2.4), (3) after calibration of the data acquisition board, injection actuator air pressure sensor or charge
air pressure sensor, (4) whenever check standard or QC sample determinations are not in statistical control as determined by
Practice D6299 or equivalent and the assignable causes for QC non-compliance have been suitably addressed.
11.2 Precalibration Procedures:
11.2.1 Clean the combustion chamber pressure sensor assembly (see A3.3 and A3.4).
D6890 − 22
11.2.2 If necessary, start and warm-up the combustion analyzer (see A3.1).
11.3 Calibration Procedure—Two filtered calibration reference materials are tested: (1) heptane to affirm that the combustion
chamber charge air temperature setting produces ignition delay measurements for this material that are within specification limits
and, (2) methylcyclohexane to affirm that the measurement sensitivity of the combustion analyzer produces ignition delay
measurements for this material that are within specification limits.
11.3.1 Heptane Calibration Reference Material—Perform three consecutive ignition delay determinations.
11.3.1.1 The average of three acceptable ID results is required to be within 3.77 ms to 3.79 ms.
11.3.1.2 If the average ID is outside the limits, the combustion chamber outer surface temperature controller set-point requires
adjustment to cause a change in the combustion chamber charge air temperature.
NOTE 4—ID increases when the combustion chamber outer surface temperature decreases and vice versa.
11.3.1.3 If the temperature controller set-point adjustment from the previous setting, exceeds 64 °C, a system malfunction is
suspected and diagnostic procedures to determine and remedy the problem are recommended. Refer to the instructions provided
by the manufacturer.
NOTE 5—After a change of charge air cylinders that employ a blend of oxygen and nitrogen, a temperature controller set-point adjustment beyond 4 °C
can accommodate the extreme limits of the 19.9 % to 21.9 % by volume oxygen in the blend.
11.3.1.4 After a temperature controller set-point adjustment, wait at least 10. min before initiating a new calibration so that the
combustion analyzer attains thermal equilibrium.
11.3.1.5 To be an acceptable data set, each single result is required to be within 3.72 ms to 3.84 ms.
11.3.1.6 If any of the three results is outside the limits, a system malfunction is suspected and diagnostic procedures to determine
and remedy the problem are recommended before performing a new calibration. Refer to the instructions provided by the
manufacturer.
11.3.2 Methylcyclohexane Calibration Reference Material—Perform two consecutive ignition delay determinations.
11.3.2.1 To be an acceptable data set, each single result is required to be within 9.8 ms to 11.0 ms and the average of the two results
is required to be within 9.9 ms to 10.9 ms.
11.3.2.2 If either of the two single results or the average of the two results is outside the respective limits, system performance
is unacceptable and it is recommended that diagnostic procedures be used to determine and remedy the problem before performing
a new calibration. Refer to the instructions provided by the manufacturer.
11.3.3 The combustion analyzer calibration is complete when both heptane and methylcyclohexane data sets are acceptable.
11.4 Quality Control (QC Testing)—Conduct a regular statistical quality assurance (quality control) program in accordance with
the techniques of Practice D6299 or equivalent.
11.4.1 This test method requires quality control testing at the beginning of each operating period by a single ignition delay
determination for both the check standard (heptane) and one QC sample.
11.4.2 The QC sample is a typical diesel fuel oil having an ignition delay that represents the primary range of use for the
combustion analyzer.
11.4.2.1 If the combustion analyzer is used for testing fuels having a very wide range of ignition delay, it may be useful to have
a second QC sample of a different ignition delay.
D6890 − 22
11.4.3 For locations using blends of oxygen and nitrogen as the source for charge air, conduct a QC test whenever there is a change
from one cylinder to another.
NOTE 6—The oxygen content of the new oxygen and nitrogen blend may differ from that of the previous source and can have a significant effect on ID
measurements.
11.5 Check Standard—Perform a single ignition delay determination for filtered heptane.
11.5.1 This determination is acceptable if it satisfies the limits protocol specified in Practice D6299 or equivalent.
11.5.2 Prior to having established ignition delay tolerances for heptane in accordance with Practice D6299 or equivalent, use
warning limits of 60.07 ms and action limits of 60.106 ms, based on the average of the three acceptable ID results for heptane,
as per 11.3.1.
NOTE 7—The warning and action limits for heptane were determined by analysis of round robin test data.
11.6 QC Sample—Perform a single ignition delay determination for the filtered QC sample.
11.6.1 This determination is acceptable if it satisfies the limits protocol specified in Practice D6299 or equivalent.
11.7 The combustion analyzer is fit-for-use when both the check standard (heptane) and the QC sample ignition delay
determinations are acceptable. If the ignition delay determination for either material is not acceptable, conduct a new calibration
before performing further ignition delay determinations.
12. Procedure
12.1 Operating Period Procedure:
12.1.1 If necessary, warm-up the combustion analyzer (see A3.1).
12.1.2 Check the sealing integrity of the combustion chamber (see A3.5).
12.1.3 Check that the combustion analyzer is fit-for use by performing a quality control test (see 11.4).
12.2 Test Procedure:
12.2.1 Filter the diesel fuel sample at room temperature, using a non-reactive positive pressure delivery device such as a glass
syringe or glass-lined metal syringe and single-use filter element, to prepare a test specimen of sufficient volume to complete the
test method, including flushing. The recommended volume for most test purposes is 100 mL. See the instructions provided by the
manufacturer for further information.
12.2.2 Flush, fill, and purge the fuel system with the specimen (see A3.2.2).
12.2.3 Initiate an automatic ignition delay determination using the appropriate computer command (see Annex A4 for detailed
information about the test sequence).
12.2.4 Check that all standard operating conditions are in compliance.
12.2.5 If operating conditions are not in compliance, make the required adjustments and return to 12.2.2.
12.2.6 Record the average ignition delay to the nearest 0.001 ms for the calculation of the DCN (13.1).
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1532. Contact ASTM Customer
Service at [e-mail].
D6890 − 22
12.3 Discharge unused specimen and clean the fuel system (see A3.2.3 or A3.2.4) to prepare for (1) the next specimen
determination, or (2) combustion analyzer shut down (see A3.6).
13. Calculation
13.1 Calculate the derived cetane number, DCN, from average ignition delay, ID (ms), recorded as in 12.2.6 using Eq 1:
DCN 5 4.4601186.6/ID (1)
NOTE 8—Eq 1 is the same as found in D6890 – 16.
13.2 Record the DCN to the nearest 0.1.
13.3 The derivation and maintenance of Eq 1 is described in Annex A5.
14. Report
14.1 Report the following information:
14.1.1 A reference to this standard,
14.1.2 The sample identification,
14.1.3 The date of the test,
14.1.4 The ID result to the nearest hundredth (0.01 ms),
14.1.5 The DCN result to the nearest tenth (0.1),
14.1.6 The test’s average charge air temperature to the nearest tenth (0.1) °C, and
14.1.7 Any deviation, by agreement or otherwise, from the specified procedures.
15. Precision and Bias
15.1 General—The precision statements for ID and DCN are based on interlaboratory results reported to the Energy Institute (EI)
in their monthly diesel exchanges between October 2010 and January 2012 and on data reported to the ASTM National Exchange
Group (NEG) program from September 2010 through September 2017. The test results for these studies were statistically analyzed
using ASTM Practice D6300/ISO 4259 techniques and involved 44 laboratories and 100 test samples from EI and NEG combined.
The totality of samples covered the DCN range from 31.5 DCN to 75.1 DCN, and ID range from 6.90 ms to 2.64 ms.
NOTE 9—The DCN and its precision have been calculated from ignition delay results using Eq 1.
NOTE 10—The precision statements for ID and DCN found in D6890 versions up to –16 are based on an interlaboratory study conducted in 2002
(RR:D02-1602), supplemented by interlaboratory results reported to the ASTM National Exchange Group and the Energy Institute in their monthly
diesel exchanges between January 2004 and July 2009 (RR:D02-1700). The test results for the study were statistically analyzed using ASTM Practice
D6300/ISO 4259 techniques and involved, from the 2002 round robin, 10 laboratories and 15 test samples, and from the exchanges, 34 laboratories and
145 samples. The totality of samples covered the ID range from 3.24 ms to 6.24 ms (DCN range from 62.0 DCN to 34.4 DCN).
Energy Institute test method research report number IP498 – RR2013. Determination of Ignition Delay and Derived Cetane Number (DCN) of middle distillate fuels
by combustion in a constant volume chamber, available from Energy Institute, 61 New Cavendish Street, London W1G 7AR, United Kingdom and Energy Institute test
method research report number IP498 – RR2013. Determination of Ignition Delay and Derived Cetane Number (DCN) of middle distillate fuels by combustion in a constant
volume chamber, available from Energy Institute, 61 New Cavendish Street, London W1G 7AR, United Kingdom.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1897. Contact ASTM Customer
Service at [e-mail].
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1602. Contact ASTM Customer
Service at [e-mail].
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1700. Contact ASTM Customer
Service at [e-mail].
D6890 − 22
15.2 Precision:
15.2.1 Repeatability—The difference between successive results obtained by the same operator with the same apparatus, under
constant operating conditions, on identical test materials would, in the long run, in the normal and correct operation of the test
method, exceed the values calculated using the mathematical expressions in Table 1 only in one case in twenty.
15.2.2 Reproducibility—The difference between two single and independent results, obtained by different operators working in
different laboratories on identical test materials, would, in the long run, and in the normal and the correct operation of the test
method, exceed the values calculated using the mathematical expressions in Table 1 only in one case in twenty.
15.2.3 Examples of repeatability and reproducibility are shown in Table 2 for user information.
15.3 Bias—The ID determined using this test method has no bias because ID is defined only in terms of this test method.
15.4 Between-methods Bias (formerly called Relative Bias) to Test Method D613—The degree of agreement of DCN results by
this test method relative to CN results by Test Method D613 has been assessed in accordance with Practice D6708 using only those
45 of the precision samples (see 15.1) for which at least 31 non-outlying engine results were submitted. The calculations presented
below apply for DCN results between 34.5 and 56.5, and CN averages by D613 (D613 ARV) between 34.3 and 57.9 where CN
average is computed as described in 15.4.2.1.
15.4.1 No bias correction considered in Practice D6708 can further improve the agreement between results from Test Method
D6890 and Test Method D613.
15.4.1.1 Sample specific bias, as defined in Practice D6708, was observed for some samples.
15.4.1.2 The bias assessment outcome (B3) concludes that there are sample-specific biases that do not meet the Anderson-Darling
test for normality in Practice D6708. This implies that the sample-specific biases cannot be reasonably modeled by a Gaussian
(normal) distribution. Users are cautioned that they may encounter non-Gaussian sample specific biases for some materials.
15.4.2 Proportional Error Limits for a Single DCN Result Relative to a D613 ARV:
15.4.2.1 As a D6708-compliant between-methods reproducibility cannot be calculated for non-Gaussian sample-specific biases,
quantile-based statistics were computed in accordance with D6299, subsection 6.2.2. From the 1047 non-outlying DCN results on
45 fuels, the individual “errors” (the difference between a DCN result and the average of all non-outlying D613 results on the
corresponding fuels) were computed. As each fuel was measured by at least 31 D613 engines, their averages (or “Accepted
Reference Values” or “D613 ARVs”) serve as a precise approximation to the long-term expected D613 results.
15.4.2.2 The errors were divided by the corresponding D613 ARVs to produce the individual Proportional Errors:
Proportional Error =~DCN result 2 613 _ ARV!⁄D613_ARV (2)
No significant relationship between the variation of proportional errors and D613 ARV is apparent. Therefore it is reasonable
to conclude that the proportional error behavior, while it is sample-specific, is in statistical control over the range of the fuels
studied. The proportional errors are plotted in Fig. 2, along with their averages by sample and their 95 % quantile limits.
15.4.2.3 From the proportional errors in Fig. 2, fewer than 2.5 % of the proportional errors exceeded 0.048, and fewer than 2.5 %
were less than –0.058. This implies that, in the long run, 19 of 20 DCN results can be expected to be between 94.2 % and 104.8 %
of the D613 ARV (expected cetane result by D613) of that fuel. In actual CN units, these limits are 0.942 × D613 ARV to 1.048
× D613 ARV. It is anticipated that these 95 % proportional error limits will remain valid so long as the biases continue to be in
a state of statistical control. Fig. 3 is a display of individual errors, with error limits expressed in actual CN units, as derived from
the quantiles of the proportional errors.
TABLE 1 Repeatability (r) and Reproducibility (R) for Ignition
Delay (ID) and Derived Cetane Number (DCN)
ID (ms) DCN
Repeatability (r) 0.01468 × (ID – 0.1) 0.01215 × (DCN + 3.5)
Reproducibility (R) 0.02915 × (ID +2.8) 0.06201 × (DCN –13.7)
D6890 − 22
TABLE 2 Repeatability and Reproducibility Values for Information
ID (ms) Repeatability (r) Reproducibility (R)
2.6 0.037 0.157
3.0 0.043 0.169
3.5 0.050 0.184
4.0 0.057 0.198
4.5 0.065 0.213
5.0 0.072 0.227
5.5 0.079 0.242
6.0 0.087 0.257
6.5 0.094 0.271
6.9 0.100 0.283
DCN Repeatability (r) Reproducibility (R)
32 0.43 1.13
35 0.47 1.32
40 0.53 1.63
45 0.59 1.94
50 0.65 2.25
55 0.71 2.56
60 0.77 2.87
65 0.83 3.18
70 0.89 3.49
75 0.95 3.80
15.4.2.4 In Table 3, the proportional error limits calculated from the aforementioned exchange data are applied to compute 95 %
limits for the range of a single conforming DCN result on a fuel of a given D613_ARV, as computed in accordance with D6299
as described above. In the long run, 19 times out of 20:
0.942 D613_ARV # DCN # 1.048 D613_ARV (3)
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FIG. 2 Proportional Errors with Quantiles
FIG. 3 Error Limits from Proportional Error Quantiles
D6890 − 22
TABLE 3 95 % Error Limits in Cetane Units
Expected D613 Result Lower Limit of Error of Upper Limit for Error of
Single DCN Result Single DCN Result
34 –2.0 1.6
40 –2.3 1.9
45 –2.6 2.2
50 –2.9 2.4
55 –3.2 2.6
58 –3.4 2.8
15.4.2.5 In Table 4, the proportional error limits calculated from the aforementioned exchange data are applied to compute 95 %
limits for the range of a likely average D613 result of a fuel, given a single DCN result. In the long run, 19 times out of 20:
0.954 DCN =DCN/1.048 # D613_ARV # DCN/0.942 = 1.062DCN (4)
16. Keywords
16.1 cetane number; derived cetane number; diesel performance; ignition characteristic; ignition delay
ANNEXES
(Mandatory Information)
A1. HAZARDS INFORMATION
A1.1 Introduction
A1.1.1 In the performance of the standard test method there are hazards to personnel. These are indicated in the text. For more
detailed information regarding the hazards, refer to the appropriate Material Safety Data Sheet (MSDS) for each of the applicable
substances to establish risks, proper handling, and safety precautions.
A1.2 (Warning—Combustible. Vapor harmful.)
A1.2.1 Applicable Substances:
A1.2.1.1 Diesel fuel oil, and
A1.2.1.2 Quality control sample.
TABLE 4 95 % Prediction Limits for Expected D613 Result Calcu-
lated from the Proportional Error Limits
Single DCN Result Lower Prediction Limit for Upper Prediction Limit
D613_ARV for D613_ARV
34 32.4 36.1
40 38.2 42.5
45 42.9 47.8
50 47.7 53.1
55 52.5 58.4
58 55.4 61.6
D6890 − 22
A1.3 (Warning—Flammable. Vapors harmful if inhaled. Vapors may cause flash fire.)
A1.3.1 Applicable Substances:
A1.3.1.1 Heptane, and
A1.3.1.2 Methylcyclohexane.
A1.4 (Warning—Poison. May be harmful or fatal if inhaled or swallowed.)
A1.4.1 Applicable Substances:
A1.4.1.1 Ethylene glycol based antifreeze.
A1.5 (Warning—Compressed gas under high pressure that supports combustion.)
A1.5.1 Applicable Substances:
A1.5.1.1 Compressed air.
A1.6 (Warning—Compressed gas under high pressure.)
A1.6.1 Applicable Substances:
A1.6.1.1 Compressed nitrogen.
A1.7 (Warning—Hot surfaces.)
A1.7.1 Applicable Substances:
A1.7.1.1 Protective cage enclosing the combustion chamber,
A1.7.1.2 Exposed areas of the combustion chamber around the injector nozzle, and
A1.7.1.3 Exposed areas of the combustion chamber near the combustion chamber inside the combustion chamber protective cage.
D6890 − 22
A2. COMBUSTION ANALYZER EQUIPMENT DESCRIPTION AND SPECIFICATIONS
A2.1 The combustion chamber assembly and fuel injection system are critical to the proper operation of this test method.
A2.2 Combustion Chamber Assembly—The principle component of this assembly, illustrated in Fig. A2.1, is a corrosion-protected
metal cylindrical block that is precision machined
...