1、Designation: D7683 11Standard Test Method forCloud Point of Petroleum Products (Small Test Jar Method)1This standard is issued under the fixed designation D7683; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the cloudpoint of petroleum products, biodiesel, and biodiesel blendsthat are tran
3、sparent in layers 40 mm in thickness, using anautomatic instrument.1.2 The measuring range of the apparatus is from -65 to51C, however the precision statements were derived onlyfrom samples with cloud point temperatures from -50 to +6C.1.3 The values stated in SI units are to be regarded asstandard.
4、 No other units of measurement are included in thisstandard.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 practices and determine the applica-b
5、ility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2500 Test Method for Cloud Point of Petroleum ProductsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6708 Practice f
6、or StatisticalAssessment and Improvementof Expected Agreement Between Two Test Methods thatPurport to Measure the Same Property of a Material2.2 Energy Institute Standards:3IP219 Test Method for Cloud Point of Petroleum Products3. Terminology3.1 Definitions:3.1.1 biodiesel, nfuel comprising mono-alk
7、yl 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 the presence of a catalyst to yieldmono-esters and glycerin. The f
8、uel typically may contain up to14 different types of fatty acids that are chemically transformedinto fatty acid methyl esters (FAME).3.1.2 biodiesel blend (BXX), nblend of biodiesel fuel withpetroleum-based diesel fuel designated BXX, where XX is thevolume percentage (as a whole number without the p
9、ercentagesign) 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 under prescribed conditions.3.1.3.1 DiscussionThe cloud point occurs when the tem-peratu
10、re of the specimen is low enough to cause hydrocarboncrystals to precipitate. In a homogeneous liquid, the cloud isalways noted first at the location in the specimen where thespecimen temperature is the lowest. The cloud point is thetemperature at which the crystals first occur, regardless of theirl
11、ocation in the specimen, and not after extensive crystallizationhas taken place. The hydrocarbon crystals that precipitate atlower temperatures are typically, but not excluded to, straightchain hydrocarbons commonly called “wax crystals.”3.2 Definitions of Terms Specific to This Standard:3.2.1 small
12、 test jar method, nin cloud point test methods,automatic test procedure using a small sample size, prescribedcooling rate, specimen receptacle, and optical system fordetection of crystal formation.3.2.1.1 DiscussionThe prescribed cooling rate is de-scribed in 11.4, the specimen receptacle is describ
13、ed in 6.3, andthe optical system for detection of crystal formation is de-scribed in A1.2.3.1This 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 Feb. 15
14、, 2011. Published April 2011. DOI: 10.1520/D768311.2For 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
15、 from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.uk.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 D2500/IP219 equivalent cloud point, ntemperatureof a specimen, in integers, calcula
16、ted by applying a bias androunding the results of this test method to the next lowerinteger (see 12.2).3.2.2.1 DiscussionThis test method produces results with0.1C resolution. Should the user wish to provide results witha similar format to Test Method D2500, then this calculationcan be performed. So
17、me apparatus can perform this calculationautomatically.4. Summary of Test Method4.1 After inserting the glass test jar containing the specimeninto the automatic apparatus and initiating the test program, thespecimen is heated, if necessary, to the designated temperatureand then cooled by prescribed
18、rates. (See 11.4.) The testspecimen is continuously monitored for appearance of hydro-carbon crystals with a light emitter and a light receiver throughcoaxial type optical fibers. (See A1.2.3.) When the crystalliza-tion in the specimen is detected by the optical system, thetemperature is recorded to
19、 0.1C resolution. The specimen isthen heated to facilitate the start of the next test.5. Significance and Use5.1 The cloud point of petroleum products and biodieselfuels is an index of the lowest temperature of their utility forcertain applications. Wax crystals of sufficient quantity canplug filter
20、s used in some fuel systems.5.2 Petroleum blending operations require precise measure-ment of the cloud point.5.3 This test method can determine the temperature of thetest specimen at which wax crystals have formed sufficiently tobe observed as a cloud with a resolution of 0.1C.5.4 This test method
21、provides results that, when correctedfor bias and rounded to the next lower integer (see 12.2), havebeen found equivalent to Test Method D2500.5.5 This test method determines the cloud point in a shortertime period than required by Test Method D2500.6. Apparatus6.1 Automatic ApparatusThe automatic c
22、loud point appa-ratus described in this test method is a microprocessor con-trolled apparatus that is capable of heating and cooling a testspecimen at prescribed rates, optically observing the firstappearance of hydrocarbon wax crystals, and recording thetemperature of the test specimen. A detailed
23、description of theapparatus is provided in Annex A1.6.2 Temperature Measuring DeviceThe temperature mea-suring device in the specimen chamber shall be capable ofmeasuring the temperature from -65 to 51C at a resolution of0.1C.6.3 Test JarClear cylindrical borosilicate glass with a flatbottom with an
24、 approximate capacity of 12 mL.Approximately4.5 mL of sample specimen is contained when filled to thescribed line. During the test, the test jar is fitted with a test jarcap assembly on its top. See A1.1.2 for more details on the testjar.6.4 Metallic Block BathMetallic block with a cylindricalhole t
25、o fit the test jar. The metallic block assembly shall havea provision for cooling/heating. A temperature sensor is em-bedded in the metallic block to monitor its temperature.7. Reagents and Materials7.1 Cleaning AgentsCapable of cleaning and drying thetest jar and test jar cap assembly, after each t
26、est. Chemicalagents such as alcohol and petroleum-based solvents have beenfound suitable to use. (WarningFlammable.) (WarningMay be harmful by itself or when evaporated.)8. Sampling8.1 Obtain a sample in accordance with Practice D4057 orby Practice D4177.8.2 A minimum volume of 4.5 mL of sample is r
27、equired foreach test.8.3 Samples of very viscous materials may be warmed untilthey are reasonably fluid before they are tested. However, nosample should be heated more than is absolutely necessary tofacilitate pouring the sample into the instrument test jar.(WarningExercise care when selecting the p
28、reheating tem-perature. Samples which are fluid at ambient room temperaturecan also have a low flash point. Use higher preheatingtemperatures only on samples known to be solid near ambientroom temperature.)8.4 The sample shall not be heated above 60C. When thesample is heated above 60C allow the sam
29、ple to cool below60C before filtering or inserting into the apparatus.8.5 When moisture is present, remove the moisture by amethod, such as filtration through dry lint-free filter paper, untilthe oil is perfectly clear, but make such filtration at a tempera-ture at least 14C above the expected cloud
30、 point.NOTE 1Moisture will be noticed in the sample as a separate phase oras a haze throughout the entire sample. Generally, a slight haze will notinterfere with the detection of the wax cloud.9. Preparation of Apparatus9.1 Prepare the instrument for operation in accordance withthe manufacturers ins
31、tructions.10. Calibration and Standardization10.1 Ensure that all of the manufacturers instructions forcalibrating, checking and operating the apparatus are followed.10.2 A sample with a well documented cloud point can beused to verify the performance of the automatic apparatus.Alternatively, a samp
32、le that has been extensively tested in acloud point cross-check program can be used. Such verificationmaterials can also be prepared from intra-company cross-checks.11. Procedure11.1 Pour the sample specimen into the test jar to the scribedmark. When necessary, heat the sample in a bath or oven unti
33、lit is just sufficiently fluid to pour into the test jar. Samples withan expected cloud point above 36C or samples which appearsolid at room temperature can be heated above 45C, but theyshall not be heated above 60C.11.2 Insert the charged test jar into the metallic block bath,and install the test j
34、ar cap assembly snugly.D7683 11211.3 Enter the expected cloud point and start the operationof the apparatus according to the manufacturers instruction.From this point on, the apparatus automatically controls theseries of procedures, which includes the sample preheatingfunction if the apparatus is so
35、 programmed prior to the start ofthe automatic procedure. (WarningExercise care when se-lecting the preheating temperature. Samples which are fluid atambient room temperature can also have a low flash point. Usehigher preheating temperatures only on samples known to besolid near ambient room tempera
36、ture.)11.4 After the sample preheating is completed, the metallicblock bath is cooled down automatically at a typical rate of 3to 4C/min. At a temperature at least 20C above the expectedcloud point, the cooling rate slows down to 0.8 to 1.1C/min.During the cooling, the optical system monitors for ap
37、pearanceof the crystals.11.5 In the event a cloud point is detected prematurelyduring the fast cooling rate, as determined by the apparatus, thespecimen shall be reheated to a higher temperature, at least30C warmer than the temperature of premature detection, andthen cooled as described in 11.4, whi
38、le the optical systemmonitors for appearance of the crystals.11.6 At the detection of the cloud point, the specimentemperature is displayed to the nearest 0.1C and held on thedigital display. The metallic block bath starts heating automati-cally for the next test.12. Report12.1 Report the temperatur
39、e recorded in 11.6 to 0.1C as thecloud point D7683 (Small Test Jar Method).12.2 When specified, correct the results recorded in 11.6with the relative bias in accordance with 13.3, then round to thenext lower integer (a colder temperature) and report as the TestMethod D2500 equivalent cloud point in
40、accordance with TestMethod D7683.13. Precision and Bias413.1 PrecisionThe precision of this test method as deter-mined by the statistical examination of the interlaboratory testresults is as follows:13.1.1 RepeatabilityThe difference between successivetest results, obtained by the same operator usin
41、g the sameapparatus under constant operating conditions on identical testmaterial, would in the long run, in the normal and correctoperation of this test method, exceed the following only in onecase in twenty.1.47C, valid range -50 to +6C13.1.2 ReproducibilityThe difference between two singleand ind
42、ependent test results, obtained by different operatorsworking in different laboratories on identical test material,would in the long run, in normal and correct operation of thistest method, exceed the following only in one case in twenty.2.45C, valid range -50 to +6C13.2 BiasSince there is no accept
43、ed reference materialsuitable for determining the bias for the procedure in this testmethod, bias has not been determined.13.3 Relative BiasThe Degree of Agreement betweenresults by Test Method D7683 and Test Method D2500/IP219Results on the same materials produced by TestMethod D7683 and Test Metho
44、d D2500 have been assessed inaccordance with procedures outlined in Practice D6708. Thefindings are:The degree of agreement between results from Test MethodD7683 and Test Method D2500/IP219 can be further improvedby applying the bias-correction outlined in Eq 1. Sample-specific bias, as defined in P
45、ractice D6708, was observed forsome samples after applying the bias correction.Predicted Y D2500!5bias2corrected X D7683!5 X D7683!11.68C (1)where:X = result obtained by Test Method D7683,andbias-corrected X = predicted Y = result that would havebeen obtained by Test Method D2500/IP219 on the same s
46、ample.Differences between bias-corrected results from Eq 1 andTest Method D2500/IP219, for the sample types and propertyranges studied, are expected to exceed the following betweenmethod reproducibility (RXY), as defined in Practice D6708,about 5 % of the time.RXY5 3.51C (2)13.4 The precision statem
47、ents were derived from a 2009interlaboratory cooperative test program.4Participants ana-lyzed 21 sample sets comprised of 6 distillate fuels, 6 base oilstocks, 3 biodiesel (derived from soy, canola, and tallow) and6 blends of biodiesel in distillate fuel representing B5, B10 andB20 blends. The cloud
48、 point temperature range was -50C to6C. There were 12 laboratories that participated with the smalltest jar method automatic instrument and 12 laboratoriesparticipated with the manual D2500/IP219 test method. Infor-mation on the type of samples and their average cloud pointsare in the research repor
49、t available at ASTM Headquarters.414. Keywords14.1 automated cloud point; biodiesel; cloud point; petro-leum products4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1715.D7683 113ANNEX(Mandatory Information)A1. AUTOMATIC SMALL TEST JAR METHOD CLOUD POINT APPARATUSA1.1 GeneralA1.1.1 The microprocessor controlled test apparatus is de-scribed in this annex and illustrated in Fig. A1.1.A1.1.2 Test JarClear cylindrical borosilicate glass with aflat bot
