1、Designation: D2500 16b British Standard 4458Standard Test Method forCloud Point of Petroleum Products and Liquid Fuels1This 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 U.S. Department of Defense.1. Scope*1.1 This test method covers
3、only petroleum products andbiodiesel fuels that are transparent in layers 40 mm inthickness, and with a cloud point below 49 C.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 sampl
4、es with 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 li
5、ver damage. 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-tio
6、nal information. 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 stand
7、ard to 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 for ASTM Color of Petroleum Products(ASTM Color Scale)D6300 Pra
8、ctice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsD7962 Practice for Determination of Minimum ImmersionDepth and Assessment of Temperature Sensor Measure-ment DriftE1 Specification for ASTM Liquid-in-Glass ThermometersE1137 Specification fo
9、r Industrial Platinum ResistanceTher-mometersE2251 Specification for Liquid-in-Glass ASTM Thermom-eters with Low-Hazard Precision LiquidsE2877 Guide for Digital Contact Thermometers2.2 Energy Institute Standard:3Specifications for IP Standard Thermometers3. Terminology3.1 Definitions of Terms Specif
10、ic 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 areaction of vegetable oil or animal fat with an alcohol such asmethanol or ethanol in
11、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 blend, na blend of biodiesel fuel withpetroleum-based diesel fuel designated BXX, whe
12、re 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 wax crystals first occurs upon coolingunder prescribed conditions.3.1.3.1 DiscussionTo many observers, the cluster of waxcrystal
13、s 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 crystals first form at the lowercircumferential wall of the test jar where the temperature is1
14、This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.07 on Flow Properties.Current edition approved Dec. 1, 2016. Published January 2017. Originallyapproved in 1966. Last previous editi
15、on approved in 2016 as D2500 16a. DOI:10.1520/D2500-16B.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.3Avai
16、lable 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 StatesThis international st
17、andard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1low
18、est.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.3.1.3.2 DiscussionUpon cooling to temperatures lowerthan the cloud point, clusters of cryst
19、als 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 bottomcircumference, followed by extensive crystallization across thebottom of the test jar as
20、 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.3.1.3.3 DiscussionIn general, it is easier to detect thecloud point of samples with large cl
21、usters 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 thecluster when the specimen is well illuminated. For other moredifficult samples, such as
22、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 is weak,and the boundary of the cluster is more diffuse. As thetemperature of these specime
23、ns 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 specimen instead
24、 of crystal formation (see Note 5).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 inorganic
25、 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 transition of
26、 the tracecomponents, such as water.3.1.4 digital contact thermometer (DCT), nan electronicdevice consisting of a digital display and associated tempera-ture sensing probe.3.1.4.1 DiscussionThis device consists of a temperaturesensor connected to a measuring instrument; this instrumentmeasures the t
27、emperature-dependent quantity of the sensor,computes the temperature from the measured quantity, andprovides a digital output. This digital output goes to a digitaldisplay and/or recording device that may be internal or externalto the device. These devices are sometimes referred to as a“digital ther
28、mometer”.3.1.4.2 DiscussionPortable electronic thermometers(PET) is an acronym sometimes used to refer to a subset of thedevices covered by this definition.4. Summary of Test Method4.1 The specimen is cooled at a specified rate and examinedperiodically. The temperature at which a cloud is first obse
29、rvedat 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, clear, cylin
30、drical glass, flat bottom, 33.2 mm to34.8 mm outside diameter and 115 mm to 125 mm in height.The inside diameter of the jar may range from 30 mm to32.4 mm within the constraint that the wall thickness be nogreater than 1.6 mm. The jar should be marked with a line toindicate sample height 54 mm 6 3 m
31、m above the insidebottom.6.2 Temperature Measuring DeviceEither liquid-in-glassthermometers as described in 6.2.1 or digital contact thermom-eter (DCT) meeting the requirements described in 6.2.2.6.2.1 Liquid-in-Glass Thermometers, having ranges shownbelow and conforming to the requirements as presc
32、ribed inSpecifications E1 or E2251, or Specifications for IP StandardThermometers.ThermometerNumberThermometer Temperature Range ASTM IPHigh cloud and pour 38 C to +50 C 5C, S5C 1CLow cloud and pour 80 C to +20 C 6C 2CNOTE 1All dimensions are in milllimetres.FIG. 1 Apparatus for Cloud Point TestD250
33、0 16b26.2.2 Digital Contact Thermometer Requirements:4Parameter RequirementDCT Guide E2877 Class G or betterTemperature range 65 C to 90 CDisplay resolution 0.1 C minimumSensor type PRT, thermistor, thermocoupleSensor 3 mm O.D. with a sensing element less than 10 mm inlengthMinimum immersion Less th
34、an 40 mm per Practice D7962Sample immersiondepthAs shown in Fig. 1 or subsection 8.3Accuracy 500 mK (0.5 C) for combined probe and sensorResponse time less than or equal to 25 s as defined in SpecificationE1137Drift less than 500 mK (0.5 C) per yearCalibration error less than 500 mK (0.5 C) over the
35、 range of intended use.Calibration range 40 C or lower to 85 CCalibration data 4 data points evenly distributed over calibration range withdata included in calibration report.Calibration report From a calibration laboratory with demonstrated compe-tency in temperature calibration which is traceable
36、to anational calibration laboratory or metrology standards bodyNOTE 2When the DCT display is mounted on the end to the probessheath, the test jar with the probe inserted will be unstable. To resolve this,it is recommended that the probe be less than 30 cm in length but no lessthan 15 cm.A5 cm long s
37、topper that has a low thermal conductivity, withapproximately half of it inserted in the sample tube, will improve stability.6.2.2.1 The DCT calibration drift shall be checked at leastannually by either measuring the ice point or against areference thermometer in a constant temperature bath at thepr
38、escribed immersion depth to ensure compliance with 6.2.2.See Practice D7962.NOTE 3When a DCTs calibration drifts in one direction over severalcalibration checks, it may be an indication of deterioration of the DCT.6.3 Cork, to fit the test jar, bored centrally for the testthermometer.6.4 Jacket, met
39、al or glass, watertight, cylindrical, flatbottom, about 115 mm in depth, with an inside diameter of44.2 mm to 45.8 mm. It shall be supported free of excessivevibration and firmly in a vertical position in the cooling bath of6.7 so that not more than 25 mm projects out of the coolingmedium and shall
40、be capable of being cleaned.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 of rubber, leather, or other materialthat is elastic eno
41、ugh 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 requiredbath temperatures may be maintained by refrigeration ifav
42、ailable, 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 residue on drying.(WarningExtremely flammable.)7.2 Carbon
43、 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.)7.4 Sodium Chloride CrystalsCommercial or technicalgrade sodiu
44、m chloride is suitable.7.5 Sodium SulfateA reagent grade of anhydrous sodiumsulfate should be used when required (see Note 6).7.6 Ethanol or Ethyl AlcoholA commercial or technicalgrade of dry ethanol is suitable for the cooling bath.(WarningFlammable. Denatured, cannot be made non-toxic.)7.7 Methano
45、l 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 sample to be tested to a temperature at least14 C above the expected cloud point. Remove any moisturepresent by a method such as filtration
46、 through dry lintless filterpaper until the oil is perfectly clear, but make such filtration ata temperature of at least 14 C above the approximate cloudpoint.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1849. ContactASTM
47、 CustomerService at serviceastm.org.TABLE 1 Cooling Mixtures and Bath TemperaturesBath TemperatureIce and water 0C1.5CCrushed ice and sodium chloride crystals, orAcetone or petroleum naphtha or methanol or ethanol (see Section 7)with solid carbon dioxide added to give the desired temperature18 C 1.5
48、 CAcetone or petroleum naphtha or methanol or ethanol (see Section 7)with solid carbon dioxide added to give the desired temperature33 C 1.5 CAcetone or petroleum naphtha or methanol or ethanol (see Section 7)with solid carbon dioxide added to give the desired temperature51 C 1.5 CAcetone or petrole
49、um naphtha or methanol or ethanol (see Section 7)with solid carbon dioxide added to give the desired temperature69 C 1. 5 CD2500 16b38.2 Pour the sample into the test jar to the level mark.8.3 If using a liquid-in-glass thermometer and the expectedcloud point is above 36 C then use the high cloud and pourpoint thermometer; otherwise use the low cloud and pourthermometer. Close the test jar tightly by the cork carrying thetest thermometer, and adjust the position of the cork and thethermometer so that
