1、Designation:D250011British Standard 4458Standard Test Method forCloud Point of Petroleum Products1This standard is issued under the fixed designation D2500;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A n
2、umber 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 only petroleum products andbio
3、diesel fuels that are transparent in layers 40 mm inthickness,and with a cloud point below 49C.NOTE1The interlaboratory program consisted of petroleum productsof Test Method D1500 color of 3.5 and lower.The precisions stated in thistest method may not apply to samples with ASTM color higher than 3.5
4、.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 WARNINGMercury has been designated by manyregulatory agencies as a hazardous material that can causecentral nervous system,kidney and liver damage.Mercury,orits vapor,may b
5、e hazardous to health and corrosive tomaterials.Caution should be taken when handling mercury andmercury containing products.See the applicable product Ma-terial Safety Data Sheet(MSDS)for details and EPAswebsitehttp:/www.epa.gov/mercury/faq.htmfor addi-tional information.Users should be aware that
6、selling mercuryand/or mercury containing products into your state or countrymay be prohibited by law.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
7、 practices and determine the applica-bility of regulatory limitations prior to use.For specific hazardstatements,see Section 7.2.Referenced Documents2.1 ASTM Standards:2D1500 Test Method for ASTM Color of Petroleum Products(ASTM Color Scale)E1 Specification for ASTM Liquid-in-Glass Thermometers2.2 E
8、nergy Institute Standard:3Specifications for IP Standard Thermometers3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 biodiesel,na fuel comprised of mono-alkyl esters oflong chain fatty acids derived from vegetable oils or animalfats,designated B100.3.1.1.1 DiscussionBiodiesel i
9、s typically produced by areaction of vegetable oil or animal fat with an alcohol such asmethanol or ethanol in the presence of a catalyst to yieldmono-esters and glycerin.The fuel typically may contain up to14 different types of fatty acids that are chemically transformedinto fatty acid methyl ester
10、s(FAME).3.1.2 biodiesel blend,na blend of biodiesel fuel withpetroleum-based diesel fuel designated BXX,where XX is thevolume%of biodiesel.3.1.3 cloud point,n in petroleum products and biodieselfuels,the temperature of a liquid specimen when the smallestobservable cluster of hydrocarbon crystals fir
11、st occurs uponcooling under prescribed conditions.3.1.3.1 DiscussionTo many observers,the cluster of waxcrystals looks like a patch of whitish or milky cloud,hence thename of the test method.The cloud appears when the tempera-ture of the specimen is low enough to cause wax crystals toform.For many s
12、pecimens,the crystals first form at the lowercircumferential wall of the test jar where the temperature islowest.The size and position of the cloud or cluster at the cloudpoint varies depending on the nature of the specimen.Somesamples will form large,easily observable,clusters,whileothers are barel
13、y perceptible.3.1.3.2 DiscussionUpon cooling to temperatures lowerthan the cloud point,clusters of crystals will grow in multipledirections;for example,around the lower circumference of thetest jar,towards the center of the jar,or vertically upwards.Thecrystals can develop into a ring of cloud along
14、 the bottomcircumference,followed by extensive crystallization across thebottom of the test jar as temperature decreases.Nevertheless,1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02
15、.07 on Flow Properties.Current edition approved June 1,2011.Published July 2011.Originally approvedin 1966.Last previous edition approved in 2009 as D250009.DOI:10.1520/D2500-11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For
16、Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from Energy Institute,61 New Cavendish St.,London,WIG 7AR,U.K.,http:/www.energyinst.org.uk.*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 States1 the cloud point is defined as the temperature at which thecrystals first appear,not when an entire ring or full
