ASTM_D_6468_-_08_2013.pdf

Designation:D646808(Reapproved 2013)Standard Test Method forHigh Temperature Stability of Middle Distillate Fuels1This standard is issued under the fixed designation D6468;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 test method covers relative stability of middledistillate fuels under high temperature aging conditions withlimited air exposure.This test method is suitable for all No.1and No.2 grades in Specifications D396,D975,D2880,andD3699.It is also suitable for similar fuels meeting otherspecifications.1.2 This test method is not suitable for fuels whose flashpoint,as determined by Test Methods D56,D93,or D3828,isless than 38C.This test method is not suitable for fuelscontaining residual oil.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3.1 ExceptionThe maximum vacuum includes inch-pound units in 6.5 and 11.2.1.4 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D56 Test Method for Flash Point by Tag Closed Cup TesterD93 Test Methods for Flash Point by Pensky-MartensClosed Cup TesterD396 Specification for Fuel OilsD975 Specification for Diesel Fuel OilsD1500 Test Method for ASTM Color of Petroleum Products(ASTM Color Scale)D2274 Test Method for Oxidation Stability of Distillate FuelOil(Accelerated Method)D2880 Specification for Gas Turbine Fuel OilsD3699 Specification for KerosineD3828 Test Methods for Flash Point by Small Scale ClosedCup TesterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4625 Test Method for Middle Distillate Fuel StorageStability at 43C(110F)D5452 Test Method for Particulate Contamination in Avia-tion Fuels by Laboratory Filtration3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 adherent insolublesmaterial that is produced in thecourse of stressing distillate fuel and that adheres to theglassware after fuel has been flushed from the system.3.1.2 filterable insolublesmaterial that is produced in thecourse of stressing distillate fuel and that is capable of beingremoved from the fuel by filtration.3.1.3 inherent stabilitythe resistance to change when ex-posed to air,but in the absence of other environmental factorssuch as water,reactive metal surfaces,and dirt.3.1.4 storage stabilitythe resistance of fuel to formationof degradation products when stored at ambient temperatures.3.1.5 thermal stabilitythe resistance of fuel to formationof degradation products when thermally stressed.4.Summary of Test Method4.1 Two 50-mL volumes of filtered middle distillate fuel areaged for 90 or 180 min at 150C in open tubes with airexposure.After aging and cooling,the fuel samples are filteredand the average amount of filterable insolubles is estimated bymeasuring the light reflectance of the filter pads.The 100 and0%extremes of the reflectance rating range are defined by anunused filter pad and a commercial black standard,respec-tively.5.Significance and Use35.1 This test method provides an indication of thermaloxidative stability of distillate fuels when heated to high1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved Oct.1,2013.Published October 2013.Originallyapproved in 1999.Last previous edition approved in 2008 as D6468 08.DOI:10.1520/D6468-08R13.2For 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.3Henry,C.P.,“The du Pont F21 149C(300F)Accelerated Stability Test,”Distillate Fuel Stability and Cleanliness,ASTM STP 751,Stavinoha,L.L.andHenry,C.P.,Eds.,ASTM International,1981,pp.2233.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 temperatures that simulate those that may occur in some typesof recirculating engine or burner fuel delivery systems.Resultshave not been substantially correlated to engine or burneroperation.The test method can be useful for investigation ofoperational problems related to fuel thermal stability.5.2 When the test method is used to monitor manufacture orstorage of fuels,changes in filter rating values can indicate arelative change in inherent stability.Storage stability predic-tions are more reliable whe