1、Designation: D2500 11Designation: 219/82British 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 y
2、ear 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers only
3、petroleum products andbiodiesel fuels that are transparent in layers 40 mm inthickness, and with a cloud point below 49C.NOTE 1The 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 wit
4、h ASTM color higher than 3.5.1.2 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 da
5、mage. Mercury, orits vapor, may be 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 in
6、formation. Users should be aware that 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
7、 establish appro-priate safety and health 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 forASTM Color of Petroleum Products(ASTM Color Scale)E1 Specification
8、 for ASTM Liquid-in-Glass Thermometers2.2 Energy 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,
9、 designated B100.3.1.1.1 DiscussionBiodiesel is 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 che
10、mically transformedinto fatty acid methyl esters (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, nin petroleum products and biodieselfuels, the temperature of a liquid specimen when the s
11、mallestobservable cluster of hydrocarbon crystals first 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 specim
12、en is low enough to cause wax crystals toform. For many specimens, 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
13、form large, easily observable, clusters, whileothers are barely 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 the1This test method is under the jurisdiction of
14、 ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.07 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 refe
15、renced 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.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7A
16、R,U.K., http:/www.energyinst.org.uk.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.test jar, towards the center of the jar, or vertically upwards. Thecrystals can dev
17、elop into a ring of cloud along the bottomcircumference, followed by extensive crystallization across thebottom of the test jar as temperature decreases. Nevertheless,the cloud point is defined as the temperature at which thecrystals first appear, not when an entire ring or full layer of waxhas been
18、 formed at the bottom of the test jar.3.1.3.3 DiscussionIn general, it is easier to detect thecloud point of samples with large clusters that form quickly,such as paraffinic samples. The contrast between the opacity ofthe cluster and the liquid is also sharper. In addition, smallbrightly-reflective
19、spots can sometimes be observed inside thecluster when the specimen is well illuminated. For other moredifficult samples, such as naphthenic, hydrocracked, and thosesamples whose cold flow behavior have been chemicallyaltered, the appearance of the first cloud can be less distinct.The rate of crysta
20、l growth is slow, the opacity contrast is weak,and the boundary of the cluster is more diffuse. As thetemperature of these specimens decrease below the cloudpoint, the diffuse cluster will increase in size and can form ageneral haze throughout. A slight haze throughout the entiresample, which slowly
21、 becomes more apparent as the tempera-ture of the specimen decreases, can also be caused by traces ofwater in the specimen instead of crystal formation (see Note 3).With these difficult samples, drying the sample prior to testingcan eliminate this type of interference.3.1.3.4 DiscussionThe purpose o
22、f the cloud point methodis to detect the presence of the wax crystals in the specimen;however trace amounts of water and inorganic compounds mayalso be present. The intent of the cloud point method is tocapture the temperature at which the liquids in the specimenbegin to change from a single liquid
23、phase to a two-phasesystem containing solid and liquid. It is not the intent of thistest method to monitor the phase transition of the tracecomponents, such as water.4. Summary of Test Method4.1 The specimen is cooled at a specified rate and examinedperiodically. The temperature at which a cloud is
24、first observedat the bottom of the test jar is recorded as the cloud point.5. Significance and Use5.1 For petroleum products and biodiesel fuels, cloud pointof a petroleum product is an index of the lowest temperature oftheir utility for certain applications.6. Apparatus (see Fig. 1)6.1 Test Jar, cl
25、ear, cylindrical glass, flat bottom, 33.2 to34.8-mm outside diameter and 115 and 125-mm height. Theinside diameter of the jar may range from 30 to 32.4 mm withinthe constraint that the wall thickness be no greater than 1.6mm. The jar should be marked with a line to indicate sampleheight 54 6 3 mm ab
26、ove the inside bottom.6.2 Thermometers, having ranges shown below and con-forming to the requirements as prescribed in Specification E1or Specifications for IP Standard Thermometers.ThermometerNumberThermometer Temperature Range ASTM IPHigh cloud and pour 38 to +50C 5C 1CLow cloud and pour 80 to +20
27、C 6C 2C6.3 Cork, to fit the test jar, bored centrally for the testthermometer.6.4 Jacket, metal or glass, watertight, cylindrical, flat bot-tom, about 115 mm in depth, with an inside diameter of 44.2 to45.8 mm. It shall be supported free of excessive vibration andfirmly in a vertical position in the
28、 cooling bath of 6.7 so thatnot more than 25 mm projects out of the cooling medium.6.5 Disk, cork or felt, 6-mm thick to fit loosely inside thejacket.6.6 Gasket, ring form, about 5 mm in thickness, to fit snuglyaround the outside of the test jar and loosely inside the jacket.The gasket may be made o
29、f rubber, leather, or other materialthat is elastic enough to cling to the test jar and hard enough tohold its shape. Its purpose is to prevent the test jar fromtouching the jacket.6.7 Bath or Baths, maintained at prescribed temperatureswith a firm support to hold the jacket vertical. The requiredba
30、th temperatures may be maintained by refrigeration ifavailable, otherwise by suitable cooling mixtures. Coolingmixtures commonly used for bath temperatures shown are inTable 1.7. Reagents and Materials7.1 AcetoneTechnical grade acetone is suitable for thecooling bath, provided it does not leave a re
31、sidue on drying.(WarningExtremely flammable.)7.2 Carbon Dioxide (Solid) or Dry IceA commercialgrade of dry ice is suitable for use in the cooling bath.7.3 Petroleum NaphthaA commercial or technical gradeof petroleum naphtha is suitable for the cooling bath.(WarningCombustible. Vapor harmful.)NOTEAll
32、 dimensions are in milllimetres.FIG. 1 Apparatus for Cloud Point TestD2500 1127.4 Sodium Chloride CrystalsCommercial or technicalgrade sodium chloride is suitable.7.5 Sodium SulfateA reagent grade of anhydrous sodiumsulfate should be used when required (see Note 3).7.6 Ethanol or Ethyl AlcoholA comm
33、ercial or technicalgrade of dry ethanol is suitable for the cooling bath.(WarningFlammable. Denatured, cannot be made non-toxic.)7.7 Methanol or Methyl AlcoholA commercial or techni-cal grade of dry methanol is suitable for the cooling bath.(WarningFlammable. Vapor harmful.)8. Procedure8.1 Bring the
34、 sample to be tested to a temperature at least14C above the expected cloud point. Remove any moisturepresent by a method such as filtration through dry lintless filterpaper until the oil is perfectly clear, but make such filtration ata temperature of at least 14C above the approximate cloudpoint.8.2
35、 Pour the sample into the test jar to the level mark.8.3 Close the test jar tightly by the cork carrying the testthermometer. Use the high cloud and pour thermometer if theexpected cloud point is above 36C and the low cloud andpour thermometer if the expected cloud point is below 36C.Adjust the posi
36、tion of the cork and the thermometer so that thecork fits tightly, the thermometer and the jar are coaxial, andthe thermometer bulb is resting on the bottom of the jar.NOTE 2Liquid column separation of thermometers occasionally oc-curs and may escape detection. Thermometers should be checked periodi
37、-cally and used only if their ice points are 0 6 1C, when the thermometeris immersed to the immersion line in an ice bath, and when the emergentcolumn temperature does not differ significantly from 21C.Alternatively,immerse the thermometer to a reading and correct for the resultant coolerstem temper
38、ature.8.4 See that the disk, gasket, and the inside of the jacket areclean and dry. Place the disk in the bottom of the jacket. Thedisk and jacket shall have been placed in the cooling mediuma minimum of 10 min before the test jar is inserted. The use ofa jacket cover while the empty jacket is cooli
39、ng is permitted.Place the gasket around the test jar, 25 mm from the bottom.Insert the test jar in the jacket. Never place a jar directly intothe cooling medium.NOTE 3Failure to keep the disk, gasket, and the inside of the jacketclean and dry may lead to frost formation, which may cause erroneousres
40、ults.8.5 Maintain the temperature of the cooling bath at 0 61.5C.8.6 At each test thermometer reading that is a multiple of1C, remove the test jar from the jacket quickly but withoutdisturbing the specimen, inspect for cloud, and replace in thejacket. This complete operation shall require not more t
41、han 3 s.If the oil does not show a cloud when it has been cooled to 9C,transfer the test jar to a jacket in a second bath maintained ata temperature of 18 6 1.5C (see Table 2). Do not transfer thejacket. If the specimen does not show a cloud when it has beencooled to 6C, transfer the test jar to a j
42、acket in a third bathmaintained at a temperature of 336 1.5C. For the determi-nation of very low cloud points, additional baths are required,each bath to be maintained in accordance with Table 2. In eachcase, transfer the jar to the next bath, if the specimen does notexhibit cloud point and the temp
43、erature of the specimenreaches the lowest specimen temperature in the range identifiedfor the current bath in use, based on the ranges stated in Table2.8.7 Report the cloud point, to the nearest 1C, at which anycloud is observed at the bottom of the test jar, which isconfirmed by continued cooling.N
44、OTE 4Awax cloud or haze is always noted first at the bottom of thetest jar where the temperature is lowest.Aslight haze throughout the entiresample, which slowly becomes more apparent as the temperature islowered, is usually due to traces of water in the oil. Generally this waterhaze will not interf
45、ere with the determination of the wax cloud point. Inmost cases of interference, filtration through dry lintless filter papers, suchas described in 8.1, is sufficient. In the case of diesel fuels, however, if thehaze is very dense, a fresh portion of the sample should be dried byshaking 100 mL with5
46、gofanhydrous sodium sulfate for at least 5 minand then filtering through dry lintless filter paper. Given sufficient contacttime, this procedure will remove or sufficiently reduce the water haze sothat the wax cloud can be readily discerned. Drying and filtering should bedone always at a temperature
47、 at least 14C above the approximate cloudpoint but otherwise not in excess of 49C.9. Report9.1 Report the temperature recorded in 8.7 as the cloudpoint, Test Method D2500.TABLE 1 Cooling Mixtures and Bath TemperaturesBath TemperatureIce and water 0 6 1.5CCrushed ice and sodium chloride crystals, orA
48、cetone or petroleum naphtha or methanol or ethanol (see 7) withsolid carbon dioxide added to give the desired temperature18 6 1.5CAcetone or petroleum naphtha or methanol or ethanol (see 7) withsolid carbon dioxide added to give the desired temperature33 6 1.5CAcetone or petroleum naphtha or methano
49、l or ethanol (see 7) withsolid carbon dioxide added to give the desired temperature51 6 1.5CAcetone or petroleum naphtha or methanol or ethanol (see 7) withsolid carbon dioxide added to give the desired temperature69 6 1. 5CD2500 11310. Precision and Bias10.1 The precision of this test method as determined bystatistical examination of interlaboratory results is as follows:10.1.1 RepeatabilityThe difference between two test re-sults, obtained by the same operator with the same apparatusunder constant operating conditio
