ASTM_D_6422_-_99.pdf

Designation:D 6422 99An American National StandardStandard Test Method forWater Tolerance(Phase Separation)of Gasoline-AlcoholBlends1This standard is issued under the fixed designation D 6422;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the ability of gasoline-alcoholblends to retain water in solution or in a stable suspension atthe lowest temperature to which they are likely to be stored orexposed in use.1.2 This test method is intended to measure the temperatureat which a gasoline-alcohol blend separates into two distinctphases in accordance with the criteria defined in this testmethod.Samples that form a haze are considered not to havephase separated.1.3 This test method is applicable to gasoline-alcohol blendsfor use as fuels in spark-ignition engines that contain saturatedC1to C4alcohols only.The test method does not apply to fuelsthat contain an alcohol as the primary component,such as M85or Ed85,or to gasoline-ether blends.1.4 The values stated in SI units are the standard,exceptwhen other units are specified by federal regulation.Valuesgiven in parenthesis are provided for informational purposes.1.5 This standard may involve hazardous materials,opera-tions,and equipment.This standard does not purport toaddress all of the safety concerns,if any,associated with itsuse.It is the responsibility of the user of the standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 2500 Test Method for Cloud Point of Petroleum Prod-ucts2D 4057 Practice for Manual Sampling of Petroleum andPetroleum Products3D 4306 Practice for Aviation Fuel Sample Containers forTests Affected by Trace Contamination3D 4814 Specification forAutomotive Spark-Ignition EngineFuel3D 5842 Practice for Sampling and Handling of Fuels forVolatility Measurement4E 1 Specification for ASTM Thermometers53.Terminology3.1 Definitions:3.1.1 gasoline,na volatile mixture of liquid hydrocar-bons,generally containing small amounts of additives,suitablefor use as a fuel in spark-ignition,internal combustion engines.3.1.2 gasoline-alcohol blend,na fuel consisting primarilyof gasoline,along with a substantial amount(more than 0.35mass%oxygen or more than 0.15 mass%oxygen if methanolis the only oxygenate)of one or more alcohols.3.1.3 phase separation,nthe formation of two layers,alower aqueous constituent and an upper hydrocarbon constitu-ent,separated by either a common boundary or a layer ofemulsion.3.1.3.1 DiscussionTest specimens having droplets cling-ing to the sides of the container or collected on its bottom,thatare visible to the unaided eye,are considered to be phaseseparated.4.Summary of Test Method4.1 The sample of fuel is cooled at a controlled rate to itslowest expected storage or use temperature and is periodicallyobserved for phase separation.The apparatus of Test MethodD 2500 or a dry ice-isopropyl alcohol bath may be used.Amaximum cooling rate of 2C(4F)/min is specified becausephase separation in gasoline-alcohol blends can have a rela-tively long but unpredictable induction period.5.Significance and Use5.1 Gasoline-alcohol blends have a very limited ability toretain water in solution or in a stable suspension,and if theamount of water in the blend exceeds this limit,the fuel willseparate into a lower aqueous phase and an upper hydrocarbonphase.The most important factor governing the ability of aspecific fuel to retain water without such separation is itstemperature.This test method is intended to determine the1This test method is under the jurisdiction of ASTM Committee D-2 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.A on Gasoline and Oxygenated Fuels.Current edition approved June 10,1999.Published August 1999.2Annual Book of ASTM Standards,Vol 05.01.3Annual Book of ASTM Standards,Vol 05.02.4Annual Book of ASTM Standards,Vol 05.03.5Annual Book of ASTM Standards,Vol 14.03.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.maximum temperature at which the fuel will separate.The 10thpercentile 6-h minimum temperatures or 10C(50F),which-ever is lower,for the time of year and geographic area of theUnited States in which the fuel may be stored or used aretabulated in Table 13 of Specification D 4814.The tempera-tures represent the maximum temperatures above which thefuel must not separate into two distinct phases.5.2 Since the aqueous phase can be highly corrosive tomany metals and the spark-ignition engine cannot operate onsuch a fuel that has phase separated,such separation is veryundesirable.5.3 Blends containing low-molecular weight alcohols areg