ASTM_D_6812_-_04a_2019.pdf

Designation:D681204a(Reapproved 2019)An American National StandardStandard Practice forGround-Based Octane Rating Procedures for Turbocharged/Supercharged Spark Ignition Aircraft Engines1This standard is issued under the fixed designation D6812;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.1.Scope1.1 This practice covers ground-based octane rating proce-dures for turbocharged/supercharged spark ignition aircraftengines.This practice has been developed to allow the widestrange of applicability possible but may not be appropriate forall engine types.This practice is specifically directed toground-based testing and actual in-flight octane ratings mayproduce significantly different results.1.2 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.1.3 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:2D2700 Test Method for Motor Octane Number of Spark-Ignition Engine Fuel3.Terminology3.1 Definitions:3.1.1 amine number of reference fuels above 100,ANdeterminedintermsoftheweightpercentof3-methylphenylamine in reference grade isooctane(2,2,4-trimethylpentane).For example,5%of 3-methylphenylaminein reference grade isooctane has an amine number if 105(AN 105).No attempt has been made to correlate performancenumber of leaded reference fuels to the amine number ofunleaded reference fuels,and none is implied.3.1.2 engine octane requirementone full number greaterthan the maximum number that results in knock(graphic knocklevel descriptions can be seen in Annex A1).For example,atest engine knocks on primary reference fuels with 98 and99 motor octane numbers.The test engine does not knock on aprimary reference fuel with a 100 motor octane number.Themaximum motor octane number that results in knock is 99 sothe motor octane requirement is 100.If a test engine knocks ona reference fuel with a 3 amine number and does not knock ona fuel with a 4 amine number,then the engine requirement is a4 amine number.3.1.3 full richcondition where the mixture control is at thefull-rich stop position with the fuel flow within the manufac-turers recommended settings.3.1.4 house fuel,nfor engine operation,a fuel that doesnot contain metallic additives used for engine warm-up and allnon-octane rating engine operation.3.1.5 knock,nin an aircraft spark ignition engine,abnor-mal combustion caused by autoignition of the air/fuel mixture.3.1.6 knock condition,nfor octane rating,where theknock intensity in any cylinder is light knock or greater,asdescribed in Annex A1.3.1.7 knock number,nfor octane rating,a numericalquantification of knock intensity.3.1.8 motor octane number of primary reference fuels from0 to 100the volume%of isooctane(equals 100.0)in a blendwith n-heptane(equals 0.0).3.1.9 no-knock condition,nfor octane rating,where theknock intensity in all cylinders is less than light knock.Referto Annex A1 for description of knock intensity.3.1.10 peak EGT,nfor octane rating,as the mixture ismanually leaned from a state rich of stoichiometric,the exhaustgas temperature will increase with the removal of excess fuel.As the mixture is continually leaned,a peak temperature willbe attained,after which continued leaning will result in lowerexhaust gas temperatures.3.1.11 primary reference fuels,nfor octane rating,blended fuels of reference grade isooctane and n-heptane.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.J0.02 on Spark and Compression Ignition Aviation Engine Fuels.Current edition approved May 1,2019.Published July 2019.Originally approvedin 2002.Last previous edition approved in 2014 as D6812 04a(2014).DOI:10.1520/D6812-04AR19.2For 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.Copyright 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 Intern