ASTM D2885-10a

This document is not anASTM standard and is intended only to provide the user of anASTM 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:D2885–10 Designation: D2885 – 10a
Standard Test Method for
Determination of Octane Number of Spark-Ignition Engine
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Fuels by On-Line Direct Comparison Technique
This standard is issued under the fixed designation D2885; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope*
1.1 Thistestmethodcoversthequantitativeonlinedeterminationbydirectcomparisonofthedifferenceinknockratingordelta
octane number of a stream sample of spark-ignition engine fuel from that of a comparison reference fuel.
1.2 This test method covers the methodology for obtaining an octane number using the measured delta octane number and the
octane number of the comparison reference fuel.
1.3 The comparison reference fuel is required to be of essentially the same composition as the stream sample to be analyzed
and can be a secondary fuel termed standard fuel or a tertiary fuel termed prototype fuel.
1.4 Thetestmethodutilizesaknocktestingunit/automatedanalyzersystemthatincorporatescomputercontrolofastandardized
single-cylinder, four-stroke cycle, variable compression ratio, carbureted, CFR engine with appropriate auxiliary equipment using
either Test Method D2699 Research method or Test Method D2700 Motor method operating conditions.
1.4.1 Knock measurements are based on operation of both fuels at the specific fuel-air ratio that produces maximum knock
intensity for that fuel.
1.4.2 Measured differences in knock intensity are scaled to provide a positive or negative delta octane number of the stream
sample from the comparison reference fuel when the fuels are compared at the same compression ratio.
1.4.3 Measured differences in compression ratio are scaled to provide a positive or negative delta octane number of the stream
sample from the comparison reference fuel when the fuels are compared at the same knock intensity.
1.5 This test method is limited to testing 78 to 102 octane number spark-ignition engine fuels using either research or motor
method conditions.
1.6 The octane number difference between the stream sample and the applicable comparison reference fuel is self-limiting by
specifications imposed upon the standard and prototype fuels.
1.7 Specifications for selection, preparation, storage, and dispensing of standard and prototype fuels are provided. Detailed
proceduresfordeterminationofanappropriateassignedoctanenumberforbothstandardandprototypefuelsarealsoincorporated.
1.8 ThevaluesofoperatingconditionsarestatedinSIunitsandareconsideredstandard.Thevaluesinparenthesesarehistorical
inch-pound units. The standardized CFR engine measurements continue to be expressed in inch-pound units only because of the
extensive and expensive tooling that has been created for this equipment.
1.9 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 and health practices and determine the applicability of regulatory
limitations prior to use. For more specific warning statements, see Section 8 and Annex A1.
2. Referenced Documents
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2.1 ASTM Standards:
D1193 Specification for Reagent Water
D2699 Test Method for Research Octane Number of Spark-Ignition Engine Fuel
D2700 Test Method for Motor Octane Number of Spark-Ignition Engine Fuel
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
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This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.01 on
Combustion Characteristics.
Current edition approved Feb. 15,Oct. 1, 2010. Published MarchNovember 2010. Originally approved in 1970. Last previous edition approved in 20092010 as
D2885–09.D2885–10. DOI: 10.1520/D2885-10A.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 10
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