ASTM D2500-2005 Standard Test Method for Cloud Point of Petroleum Products《石油产品始凝点的标准试验方法》.pdf

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1、Designation: D 2500 05Designation: 219/82An American National StandardBritish Standard 4458Standard Test Method forCloud Point of Petroleum Products1This standard is issued under the fixed designation D 2500; the number immediately following the designation indicates the year oforiginal adoption or,

2、 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1

3、.1 This test method covers only 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 productsofTest Method D 1500 color of 3.5 and lower.The precisions stated in thistest meth

4、od may not apply to samples with ASTM color higher than 3.5.1.2 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 and health practices and determine the applica-b

5、ility of regulatory limitations prior to use. For specific hazardstatements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D 1500 Test Method for ASTM Color of Petroleum Prod-ucts (ASTM Color Scale)E1 Specification for ASTM Liquid-in-Glass Thermometers2.2 Energy Institute Standard:Specifi

6、cations for IP Standard Thermometers33. 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 is typically produced by areac

7、tion 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 esters (FAME).3.1.2 biodiesel ble

8、nd, 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 smallestobservable cluster of hydrocarbon crystals first occurs uponcooling

9、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 specimens, the crys

10、tals 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 barely perceptible

11、.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 the bo

12、ttomcircumference, 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 formed at the bottom of the test jar.

13、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 spots can sometimes be observed inside

14、 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 crystal growth is slow, the opacity contrast

15、 is weak,1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.07 on Flow Properties.Current edition approved July 1, 2005. Published August 2005. Originallyapproved in 1966. Last previous edition app

16、roved in 2002 as D 250002e1.2For 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.3Available from Energy Institute,

17、 61 New Cavendish St., London, EnglandWIM8AR.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.and the boundary of the cluster is more diffuse. As thetemperature of thes

18、e 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 becomes more apparent as the tempera-ture of the specimen decreases, can also be caused by traces ofwater in the specime

19、n instead of crystal formation (see Note 4).With these difficult samples, drying the sample prior to testingcan eliminate this type of interference.3.1.3.4 DiscussionThe purpose of the cloud point methodis to detect the presence of the wax crystals in the specimen;however trace amounts of water and

20、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 phase to a two-phasesystem containing solid and liquid. It is not the intent of thistest method to monitor the phase tran

21、sition 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 first observedat the bottom of the test jar is recorded as the cloud point.5. Significance and Use5.1 For petroleum produ

22、cts 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, clear, cylindrical glass, flat bottom, 33.2 to34.8-mm outside diameter and 115 and 125-mm height. Theinside diameter of the

23、 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 above the inside bottom.6.2 Thermometers, having ranges shown below and con-forming to the requirements as prescribed in Sp

24、ecification E1or Specifications for IP Standard Thermometers.ThermometerNumberThermometer Temperature Range ASTM IPHigh cloud and pour 38 to +50C 5C 1CLow cloud and pour 80 to +20C 6C 2C6.3 Cork, to fit the test jar, bored centrally for the testthermometer.6.4 Jacket, metal or glass, watertight, cyl

25、indrical, 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 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

26、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 of rubber, leather, or other materialthat is elastic enough to cling to the test jar and hard enough tohold its shape. Its

27、 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 requiredbath temperatures may be maintained by refrigeration ifavailable, otherwise by suitable freezing mixtures.NOTE 2The mixture

28、s commonly used for temperatures down to thoseshown are as follows:Ice and water 10CCrushed ice and sodium chloride crystals 12CCrushed ice and calcium chloride crystals 26CAcetone, methyl or ethyl alcohol, or petroleum naphthachilled in a covered metal beaker with an ice-salt mix-ture to 12C, then

29、with enough solid carbon dioxide togive the desired temperature57C7. Reagents and Materials7.1 AcetoneTechnical grade acetone is suitable for thecooling bath, provided it does not leave a residue on drying.(WarningExtremely flammable.)7.2 Calcium ChlorideCommercial or technical grade cal-cium chlori

30、de is suitable.7.3 Carbon Dioxide (Solid) or Dry IceA commercialgrade of dry ice is suitable for use in the cooling bath.7.4 Ethanol or Ethyl AlcoholA commercial or technicalgrade of dry ethanol is suitable for the cooling bath.(WarningFlammable. Denatured, cannot be made non-toxic.)7.5 Methanol or

31、Methyl AlcoholA commercial or techni-cal grade of dry methanol is suitable for the cooling bath.(WarningFlammable. Vapor harmful.)7.6 Petroleum NaphthaA commercial or technical gradeof petroleum naphtha is suitable for the cooling bath.(WarningCombustible. Vapor harmful.)7.7 Sodium Chloride Crystals

32、Commercial or technicalgrade sodium chloride is suitable.7.8 Sodium SulfateA reagent grade of anhydrous sodiumsulfate should be used when required (see Note 4).NOTEAll dimensions are in milllimetres.FIG. 1 Apparatus for Cloud Point TestD25000528. Procedure8.1 Bring the sample to be tested to a tempe

33、rature 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 Pour the sample into the test

34、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 position of the cork and the thermo

35、meter so that thecork fits tightly, the thermometer and the jar are coaxial, andthe thermometer bulb is resting on the bottom of the jar.NOTE 3Liquid column separation of thermometers occasionally oc-curs and may escape detection. Thermometers should be checked periodi-cally and used only if their i

36、ce 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 temperature.8.4 See that the disk, ga

37、sket, 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 cooling is permitted.Place the gaske

38、t 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 4Failure to keep the disk, gasket, and the inside of the jacketclean and dry may lead to frost formation, which may cause erroneousresults.8.5 Maintain the temperatu

39、re 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 than 3 s.If the oil does not sho

40、w 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 1). Do not transfer thejacket. If the specimen does not show a cloud when it has beencooled to 6C, transfer the test jar to a jacket in a third bathmaintained

41、 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 1. In eachcase, transfer the jar to the next bath, if the specimen does notexhibit cloud point and the temperature of the specimenreaches

42、the lowest specimen temperature in the range identifiedfor the current bath in use, based on the ranges stated in Table1.8.7 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.NOTE 5Awax cloud or haze is alwa

43、ys 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 interfere with the determination of t

44、he 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 with5gofanhydrous sodium sulfate for

45、 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 at least 14C above the approxi

46、mate cloudpoint but otherwise not in excess of 49C.9. Report9.1 Report the temperature recorded in 8.7 as the cloudpoint, Test Method D 2500.10. Precision and Bias10.1 The precision of this test method as determined bystatistical examination of interlaboratory results is as follows:10.1.1 Repeatabil

47、ityThe difference between two test re-sults, obtained by the same operator with the same apparatusunder constant operating conditions on identical test material,would in the long run, in the normal and correct operation ofthis test method, exceed 2C only in 1 case in 20.10.1.2 ReproducibilityThe dif

48、ference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material, would inthe long run, in the normal and correct operation of this testmethod, exceed 4C only in 1 case in 20.10.1.3 The precision statements were derived f

49、rom a 1990interlaboratory cooperative test program.4Participants ana-lyzed 13 sample sets comprised of various distillate fuels andlubricating oils with temperature range from -1 to -37C. Eightlaboratories participated with the manual D 2500/IP219 testmethod. Information on the type of samples and their averagecloud points are in the research report.10.2 BiasThe procedure in this test method has no bias,because the value of cloud point can be defined only in termsof a test method.10.3 Precision for Biodiesel Products5Th