ASTM D2699-24a
(Test Method)Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel
Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel
SIGNIFICANCE AND USE
5.1 Research O.N. correlates with commercial automotive spark-ignition engine antiknock performance under mild conditions of operation.
5.2 Research O.N. is used by engine manufacturers, petroleum refiners and marketers, and in commerce as a primary specification measurement related to the matching of fuels and engines.
5.2.1 Empirical correlations that permit calculation of automotive antiknock performance are based on the general equation:
Values of k1, k2, and k3 vary with vehicles and vehicle populations and are based on road-O.N. determinations.
5.2.2 Research O.N., in conjunction with Motor O.N., defines the antiknock index of automotive spark-ignition engine fuels, in accordance with Specification D4814. The antiknock index of a fuel approximates the Road octane ratings for many vehicles, is posted on retail dispensing pumps in the U.S., and is referred to in vehicle manuals.
This is more commonly presented as:
5.2.3 Research O.N. is also used either alone or in conjunction with other factors to define the Road O.N. capabilities of spark-ignition engine fuels for vehicles operating in areas of the world other than the United States.
5.3 Research O.N. is used for measuring the antiknock performance of spark-ignition engine fuels that contain oxygenates.
5.4 Research O.N. is important in relation to the specifications for spark-ignition engine fuels used in stationary and other nonautomotive engine applications.
SCOPE
1.1 This laboratory test method covers the quantitative determination of the knock rating of liquid spark-ignition engine fuel in terms of Research O.N., including fuels that contain up to 25 % v/v of ethanol. However, this test method may not be applicable to fuel and fuel components that are primarily oxygenates.2 The sample fuel is tested using a standardized single cylinder, four-stroke cycle, variable compression ratio, carbureted, CFR engine run in accordance with a defined set of operating conditions. The O.N. scale is defined by the volumetric composition of PRF blends. The sample fuel knock intensity is compared to that of one or more PRF blends. The O.N. of the PRF blend that matches the K.I. of the sample fuel establishes the Research O.N.
1.2 The O.N. scale covers the range from 0 to 120 octane number but this test method has a working range from 40 to 120 Research O.N. Typical commercial fuels produced for spark-ignition engines rate in the 88 to 101 Research O.N. range. Testing of gasoline blend stocks or other process stream materials can produce ratings at various levels throughout the Research O.N. range.
1.3 The values of operating conditions are stated in SI units and are considered standard. The values in parentheses are the historical inch-pound units. The standardized CFR engine measurements continue to be in inch-pound units only because of the extensive and expensive tooling that has been created for this equipment.
1.4 For purposes of determining conformance with all specified limits in this standard, an observed value or a calculated value shall be rounded “to the nearest unit” in the last right-hand digit used in expressing the specified limit, in accordance with the rounding method of Practice E29.
1.5 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. For specific warning statements, see Section 8, 14.4.1, 15.5.1, 16.6.1, Annex A1, A2.2.3.1, A2.2.3.3 (6) and (9), A2.3.5, X3.3.7, X4.2.3.1, X4.3.4.1, X4.3.9.3, X4.3.11.4, and X4.5.1.8.
1.6 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, Gu...
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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: D2699 − 24a
Standard Test Method for
1
Research Octane Number of Spark-Ignition Engine Fuel
This standard is issued under the fixed designation D2699; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This laboratory test method covers the quantitative
responsibility of the user of this standard to establish appro-
determination of the knock rating of liquid spark-ignition
priate safety, health, and environmental practices and deter-
engine fuel in terms of Research O.N., including fuels that
mine the applicability of regulatory limitations prior to use.
contain up to 25 % v/v of ethanol. However, this test method
For specific warning statements, see Section 8, 14.4.1, 15.5.1,
may not be applicable to fuel and fuel components that are
2 16.6.1, Annex A1, A2.2.3.1, A2.2.3.3 (6) and (9), A2.3.5,
primarily oxygenates. The sample fuel is tested using a
X3.3.7, X4.2.3.1, X4.3.4.1, X4.3.9.3, X4.3.11.4, and X4.5.1.8.
standardized single cylinder, four-stroke cycle, variable com-
1.6 This international standard was developed in accor-
pression ratio, carbureted, CFR engine run in accordance with
dance with internationally recognized principles on standard-
a defined set of operating conditions. The O.N. scale is defined
ization established in the Decision on Principles for the
by the volumetric composition of PRF blends. The sample fuel
Development of International Standards, Guides and Recom-
knock intensity is compared to that of one or more PRF blends.
mendations issued by the World Trade Organization Technical
The O.N. of the PRF blend that matches the K.I. of the sample
Barriers to Trade (TBT) Committee.
fuel establishes the Research O.N.
1.2 The O.N. scale covers the range from 0 to 120 octane
2. Referenced Documents
number but this test method has a working range from 40 to
3
2.1 ASTM Standards:
120 Research O.N. Typical commercial fuels produced for
D1193 Specification for Reagent Water
spark-ignition engines rate in the 88 to 101 Research O.N.
D2268 Test Method for Analysis of High-Purity n-Heptane
range. Testing of gasoline blend stocks or other process stream
and Isooctane by Capillary Gas Chromatography
materials can produce ratings at various levels throughout the
D2700 Test Method for Motor Octane Number of Spark-
Research O.N. range.
Ignition Engine Fuel
1.3 The values of operating conditions are stated in SI units
D2885 Test Method for Determination of Octane Number of
and are considered standard. The values in parentheses are the
Spark-Ignition Engine Fuels by On-Line Direct Compari-
historical inch-pound units. The standardized CFR engine
son Technique
measurements continue to be in inch-pound units only because
D3703 Test Method for Hydroperoxide Number of Aviation
of the extensive and expensive tooling that has been created for
Turbine Fuels, Gasoline and Diesel Fuels
this equipment.
D4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.4 For purposes of determining conformance with all
specified limits in this standard, an observed value or a D4175 Terminology Relating to Petroleum Products, Liquid
Fuels, and Lubricants
calculated value shall be rounded “to the nearest unit” in the
last right-hand digit used in expressing the specified limit, in D4177 Practice for Automatic Sampling of Petroleum and
Petroleum Products
accordance with the rounding method of Practice E29.
D4814 Specification for Automotive Spark-Ignition Engine
Fuel
D5842 Practice for Sampling and Handling of Fuels for
1
This test method is under the jurisdiction of ASTM Committee D02 on
Volatility Measurement
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.01 on Combustion Characteristics.
Current edition approved May 1, 2024. Published May 2024. Originally
approved in 1968. Last previous edition approved in 2024 as D2699 – 24. DOI:
3
10.1520/D2699-24A. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
2
Motor O.N., determined using Test Method D2700, is a companion method to contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
provide a similar but typically lower octane rating under more severe operating Standards volume informatio
...
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: D2699 − 24 D2699 − 24a
Standard Test Method for
1
Research Octane Number of Spark-Ignition Engine Fuel
This standard is issued under the fixed designation D2699; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This laboratory test method covers the quantitative determination of the knock rating of liquid spark-ignition engine fuel in
terms of Research O.N., including fuels that contain up to 25 % v/v of ethanol. However, this test method may not be applicable
2
to fuel and fuel components that are primarily oxygenates. The sample fuel is tested using a standardized single cylinder,
four-stroke cycle, variable compression ratio, carbureted, CFR engine run in accordance with a defined set of operating conditions.
The O.N. scale is defined by the volumetric composition of PRF blends. The sample fuel knock intensity is compared to that of
one or more PRF blends. The O.N. of the PRF blend that matches the K.I. of the sample fuel establishes the Research O.N.
1.2 The O.N. scale covers the range from 0 to 120 octane number but this test method has a working range from 40 to 120
Research O.N. Typical commercial fuels produced for spark-ignition engines rate in the 88 to 101 Research O.N. range. Testing
of gasoline blend stocks or other process stream materials can produce ratings at various levels throughout the Research O.N.
range.
1.3 The values of operating conditions are stated in SI units and are considered standard. The values in parentheses are the
historical inch-pound units. The standardized CFR engine measurements continue to be in inch-pound units only because of the
extensive and expensive tooling that has been created for this equipment.
1.4 For purposes of determining conformance with all specified limits in this standard, an observed value or a calculated value
shall be rounded “to the nearest unit” in the last right-hand digit used in expressing the specified limit, in accordance with the
rounding method of Practice E29.
1.5 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. For specific warning statements, see Section 8, 14.4.1, 15.5.1, 16.6.1, Annex A1, A2.2.3.1,
A2.2.3.3 (6) and (9), A2.3.5, X3.3.7, X4.2.3.1, X4.3.4.1, X4.3.9.3, X4.3.11.4, and X4.5.1.8.
1.6 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.
1
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 March 1, 2024May 1, 2024. Published April 2024May 2024. Originally approved in 1968. Last previous edition approved in 20232024 as
D2699 – 23b.D2699 – 24. DOI: 10.1520/D2699-24.10.1520/D2699-24A.
2
Motor O.N., determined using Test Method D2700, is a companion method to provide a similar but typically lower octane rating under more severe operating conditions.
*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
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D2699 − 24a
2. Referenced Documents
3
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D2268 Test Method for Analysis of High-Purity n-Heptane and Isooctane by Capillary Gas Chromatography
D2700 Test Method for Motor Octane Number of Spark-Ignition Engine Fuel
D2885 Test Method for Determination of Octane Number of Spark-Ignition Engine Fuels by On-Line Direct Comparison
Technique
D3703 Test Method for Hydroperoxide Number of Aviation Turbine Fuels, Gasoline and Diesel Fuels
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating
...
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