ASTM_D_2885_-_21.pdf

Designation:D288521Standard Test Method forDetermination of Octane Number of Spark-Ignition EngineFuels by On-Line Direct Comparison Technique1This standard is issued under the fixed designation D2885;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript 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 test method covers the quantitative online determi-nation by direct comparison of the difference in knock rating ordelta octane number of a stream sample of spark-ignitionengine fuel from that of a comparison reference fuel.1.2 This test method covers the methodology for obtainingan octane number using the measured delta octane number andthe octane number of the comparison reference fuel.1.3 The comparison reference fuel is required to be ofessentially the same composition as the stream sample to beanalyzed and can be a secondary fuel termed standard fuel ora tertiary fuel termed prototype fuel.1.4 The test method utilizes a knock testing unit/automatedanalyzer system that incorporates computer control of a stan-dardized single-cylinder,four-stroke cycle,variable compres-sion ratio,carbureted,CFR engine with appropriate auxiliaryequipment using either Test Method D2699 Research methodor Test Method D2700 Motor method operating conditions.1.4.1 Knock measurements are based on operation of bothfuels at the fuel-air ratio that produces maximum knockintensity for that fuel.1.4.2 Measured differences in knock intensity are scaled toprovide a positive or negative delta octane number of thestream sample from the comparison reference fuel when thefuels are compared at the same compression ratio.1.4.3 Measured differences in compression ratio are scaledfrom the appropriate guide table to provide a positive ornegative delta octane number of the stream sample from thecomparison reference fuel when the fuels are compared at thesame knock intensity.1.5 This test method is limited to testing 78 to 102 octanenumber spark-ignition engine fuels using either research ormotor method conditions.1.6 The octane number difference between the streamsample and the applicable comparison reference fuel is self-limiting by specifications imposed upon the standard andprototype fuels.1.7 Specifications for selection,preparation,storage,anddispensing of standard and prototype fuels are provided.Detailed procedures for determination of an appropriate as-signed octane number for both standard and prototype fuels arealso incorporated.1.8 The values of operating conditions are stated in SI unitsand are considered standard.The values in parentheses arehistorical inch-pound units.The standardized CFR enginemeasurements continue to be expressed in inch-pound unitsonly because of the extensive and expensive tooling that hasbeen created for this equipment.1.9 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For more specific warning statements,see Section 8 and AnnexA1.1.10 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD2699 Test Method for Research Octane Number of Spark-Ignition Engine FuelD2700 Test Method for Motor Octane Number of Spark-Ignition Engine Fuel1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.01 on Combustion Characteristics.Current edition approved July 1,2021.Published July 2021.Originally approvedin 1970.Last previous edition approved in 2020 as D2885 20.DOI:10.1520/D2885-21.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Techn