1、Designation: D2500 17a 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific hazard statements, see Section 7.1.5 This international standard was developed in accor-dance with internationally recognized principles on s
8、tandard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1500 Test Method for ASTM Color of Petrol
9、eum Products(ASTM Color Scale)D6300 Practice 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-G
10、lass ThermometersE644 Test Methods for Testing Industrial Resistance Ther-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. Termi
11、nology3.1 Definitions:3.1.1 digital contact thermometer (DCT), nan electronicdevice consisting of a digital display and associated tempera-ture sensing probe.3.1.1.1 DiscussionThis device consists of a temperaturesensor connected to a measuring instrument; this instrumentmeasures the temperature-dep
12、endent 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 referred to as “digitalthermometers.”3.1.1.2 Discussi
13、onPET is an acronym for portable elec-tronic thermometers, a subset of digital contact thermometers(DCT).1This 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.Curr
14、ent edition approved Dec. 1, 2017. Published January 2018. Originallyapproved in 1966. Last previous edition approved in 2017 as D2500 17. DOI:10.1520/D2500-17A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
15、f 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,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides an
17、d Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2 Definitions of Terms Specific to This Standard:3.2.1 biodiesel, na fuel comprised of mono-alkyl esters oflong chain fatty acids derived from vegetable oils or animalfats, designated B100.3.2.1.1
18、 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 chemically transformedinto
19、fatty acid methyl esters (FAME).3.2.2 biodiesel blend, na blend of biodiesel fuel withpetroleum-based diesel fuel designated BXX, where XX is thevolume % of biodiesel.3.2.3 cloud point, nin petroleum products and biodieselfuels, the temperature of a liquid specimen when the smallestobservable cluste
20、r of wax crystals first occurs upon coolingunder prescribed conditions.3.2.3.1 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 cr
21、ystals 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 form large, easily observable, c
22、lusters, whileothers are barely perceptible.3.2.3.2 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 ca
23、n develop 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
24、 been formed at the bottom of the test jar.3.2.3.3 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-reflec
25、tive 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 c
26、rystal 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 s
27、lowly 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 6).With these difficult samples, drying the sample prior to testingcan eliminate this type of interference.3.2.3.4 DiscussionThe purp
28、ose of 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 li
29、quid 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 clou
30、d is 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 Ja
31、r, clear, cylindrical 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 hei
32、ght 54 mm 6 3 mm 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.NOTE 1All dimensions are in milllimetres.FIG. 1 Apparatus for Cloud Point TestD2500 17a26
33、.2.1 Liquid-in-Glass Thermometers, having ranges shownbelow and conforming to the requirements as prescribed 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 pou
34、r 80 C to +20 C 6C 2C6.2.2 Digital Contact Thermometer Requirements:4Parameter RequirementDCT Guide E2877 Class F or betterNominal Tempera-ture rangeAHigh Cloud: 38 C to +50 CLow Cloud: 80 C to +20 CDisplay resolution 0.1 C minimumAccuracyB500 mK (0.5 C)Sensor type Platinum Resistance Thermometer (P
35、RT), thermistorSensor sheathC4.2 mm O.D. maximumSensor lengthDLess than 10 mmImmersion depthELess than 40 mm per Practice D7962Sample immersiondepthAs shown in Fig. 1 or subsection 8.3Measurement DriftEless than 500 mK (0.5 C) per yearResponse timeFless than or equal to 4 s per Footnote FCalibration
36、 error less than 500 mK (0.5 C) over the range of intended use.Calibration range Consistent with temperature range of useCalibration data Four data points evenly distributed over the calibrationrange that is consistent with the range of use. The calibra-tion data is to be included in calibration rep
37、ort.Calibration report From a calibration laboratory with demonstrated compe-tency in temperature calibration which is traceable to anational calibration laboratory or metrology standards bodyAThe nominal temperature range may be different from the values shown providedthe calibration and accuracy c
38、riteria are met.BAccuracy is the combined accuracy of the DCT unit which is the display andsensor.CSensor sheath is the tube that holds the sensing element. The value is theoutside diameter of the sheath segment containing the sensor element.DThe physical length of the temperature sensing element.EA
39、s determined by Practice D7962 or an equivalent procedure.FResponse TimeThe time for a DCT to respond to a step change in temperature.The response time is 63.2 % of the step change time as determined per Section 9of Test Method E644. The step change evaluation begins at 20 C 5 C air to77 C 5 C with
40、water circulating at 0.9 m s 0.09 m s past the sensor.NOTE 2When making measurements below 40 C with a PRT, itmay be necessary to use a 1000 ohm sensor in order to obtain accuratemeasurements.NOTE 3When the DCT display is mounted on the end to the probessheath, the test jar with the probe inserted w
41、ill 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 stopper 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 che
42、cked at leastannually by either measuring the ice point or against areference thermometer in a constant temperature bath at theprescribed immersion depth to ensure compliance with 6.2.2.See Practice D7962.NOTE 4When a DCTs calibration drifts in one direction over severalcalibration checks, it may be
43、 an indication of deterioration of the DCT.6.3 Cork, to fit the test jar, bored centrally for the testthermometer.6.4 Jacket, metal 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
44、 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 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 outs
45、ide 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 purpose is to prevent the test jar fromtouching the jacket.6.7 Bath or Baths, maintained at prescribed t
46、emperatureswith a firm support to hold the jacket vertical. The requiredbath 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 grad
47、e acetone is suitable for thecooling bath, provided it does not leave a residue on drying.(WarningExtremely flammable.)7.2 Carbon Dioxide (Solid) or Dry IceA commercialgrade of dry ice is suitable for use in the cooling bath.4Supporting data have been filed at ASTM International Headquarters and may
48、be obtained by requesting Research Report RR:D02-1849. ContactASTM 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
49、solid carbon dioxide added to give the desired temperature18 C 1.5 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 petroleum naphtha or methanol or ethanol (see Section 7)with solid carbon dioxide added to give the desired temperature69 C 1. 5 CD2500 17a37.
