1、Designation: D7689 11Standard Test Method forCloud Point of Petroleum Products (Mini Method)1This standard is issued under the fixed designation D7689; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber 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 blends,that are transparent i
3、n layers 40 mm in thickness, using anautomatic instrument.1.2 This test method covers the range of cloud pointtemperatures from -50 to +6C.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to
4、 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-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2500 Tes
5、t Method for Cloud Point of Petroleum ProductsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6708 Practice for StatisticalAssessment and Improvementof Expected Agreement Between Two Test Methods thatPurpor
6、t to Measure the Same Property of a Material2.2 Energy Institute Standard:3IP219 Test Method for Cloud Point of Petroleum Products3. Terminology3.1 Definitions:3.1.1 biodiesel, nfuel comprising mono-alkyl esters oflong-chain fatty acids derived from vegetable oils or animalfats, designated B100.3.1.
7、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 chemically transformedin
8、to 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 percentagesign) of biodiesel.3.1.3 cloud point, nin petroleum products and biodieselfuels, the temp
9、erature 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-perature of the specimen is low enough to cause hydrocarboncrystals to precipitate. In a homogeneous liq
10、uid, 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 theirlocation in the specimen, and not after extensive crystallizationhas taken place. The hydrocarbon c
11、rystals 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 D2500/IP219 equivalent cloud point, ntemperatureof a specimen, in integers, calculated by applying a bi
12、as androunding the results of this test method to the next lowerinteger (see 12.2).3.2.1.1 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. Some apparatus can per
13、form this calculationautomatically.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, 2011. Published August 2011. DOI:10.1520/D768911.2For re
14、ferenced 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
15、7AR,U.K., http:/www.energyinst.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 mini method, nin cloud point test methods, auto-matic test procedure using a small sample size, prescribedcooling rate, specimen receptacle, and
16、 optical system fordetection of crystal formation.3.2.2.1 DiscussionThe prescribed cooling rate is de-scribed in 4.1, the specimen receptacle is described in 7.1, andthe optical system for detection of crystal formation is de-scribed in 4.1.4. Summary of Test Method4.1 After inserting the test speci
17、men into the automaticapparatus, and initiation of the program, the test specimen isheated, if necessary, to a starting temperature and then cooledby prescribed rates (11.5 and 11.6). The test specimen iscontinuously monitored for appearance of hydrocarbon crystalswith opposing light emitter and opt
18、ical receiver (Annex A1).When the crystallization in the specimen is detected by theoptical system, the temperature is recorded to within 0.1Cresolution. The specimen is then heated to facilitate the start ofthe next test.5. Significance and Use5.1 The cloud point of petroleum products and biodiesel
19、fuels is an index of the lowest temperature of their utility forcertain applications. Wax crystals of sufficient quantity canplug filters 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
20、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 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
21、determines the cloud point in a shortertime period than required by Test Method D2500.6. Apparatus6.1 Automated Apparatus4The apparatus consists of amicroprocessorcontrolled test specimen chamber that is ca-pable of heating and cooling the test specimen at required rates,optically observing the firs
22、t appearance of hydrocarbon waxcrystals, and recording the temperature of the test specimenchamber. A detailed description of the apparatus is provided inAnnex A1.6.2 The apparatus shall be equipped with a thermostaticallycontrolled specimen chamber, digital display, cooling andheating systems, opti
23、cal detection system, and a specimenchamber temperature measuring device.6.3 The temperature measuring device in the specimenchamber shall be capable of measuring the temperature, atminimum, from -60 to 60C at a resolution of 0.1C.7. Reagents and Materials7.1 Specimen VialDisposable, clear glass cyl
24、inder withclosed flat bottom, 1 mL capacity.NOTE 1Standard NWV type vial is suitable.Dimensions:Outer diameter: 8.0 to 8.3 mmWall thickness: 0.75 to 0.85 mmOuter length: 39.25 to 40.25 mm7.2 Specimen Vial Stopper4Disposable, proprietary de-signed for use in this apparatus.7.3 MicropipetteCapable of
25、delivering 0.5 6 0.1 mL ofsample. Positive displacement type micropipette with capillarypiston is preferred for use.Air-displacement type micropipettesare not recommended for viscous samples.8. Sampling8.1 Obtain a sample in accordance with Practice D4057 orby Test Method D4177.8.2 At least 1 mL of
26、sample is required for each 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.8.4 The sample shall not be heated above 60C. When thesample is heated above 60C allow the
27、sample 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 cl
28、oud point.NOTE 2Moisture 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
29、instructions.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 s
30、ample that has been extensively tested in acloud point cross-check program can be used. Such verificationmaterials can also be prepared from intracompany cross-checks.11. Procedure11.1 Draw 0.5 6 0.1 mL of sample into a micro-pipette andtransfer the specimen into a new clean, dry specimen vial.When
31、necessary, heat the sample in a water bath or oven untilit is just sufficiently fluid to transfer. Samples with an expectedcloud point (ECP) above 25C or which appear solid at roomtemperature can be heated above 45C but shall not be heatedabove 60C.4The sole source of supply of the apparatus (ISL Mo
32、del MPP 5Gs analyzer)known to the committee at this time is ISL, B.P. 70825 14653, Verson, France. Ifyou are aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical co
33、mmittee,1which you may attend.D7689 11211.2 Place a new clean, dry specimen vial stopper on thespecimen vial and insert the assembly into the apparatus. Startthe operation of the apparatus according to the manufacturersinstructions.11.3 When the expected cloud point of the specimen isknown, program
34、it in the apparatus as ECP (expected cloudpoint) and start test sequence. From this point up to andincluding the termination of the test, recording and reporting ofthe result, the apparatus automatically controls the procedure.11.4 The apparatus shall adjust the specimen chamber to apreselected star
35、ting temperature. By default, the preselectedstarting temperature is 25C. Alternatively, the operator canpreprogram a defined starting temperature between 25 and60C, if desired. When the expected cloud point is known andprogrammed in the apparatus, the starting temperature shall beat least 10C warme
36、r than the expected cloud point. In theevent that the preselected starting temperature is programmedlower than 10C above the programmed expected cloud point,the apparatus shall heat the specimen chamber to a startingtemperature at least 10C above the expected cloud point, butnot more than 60C. (Warn
37、ingExercise care when selectingstarting temperatures above 40C. Samples which are fluid atambient room temperature can also have a low temperatureflash point. Use higher start temperatures only on samplesknown to be solid near ambient room temperature.)11.5 When the expected cloud point of the speci
38、men is notknown, once the starting temperature is reached (see 11.4) coolthe specimen chamber at a rate of 1.5 6 0.15C/min, while theoptical system monitors for the appearance of the crystals.11.6 When the expected cloud point of the specimen isknown, and programmed into the apparatus, once the star
39、tingtemperature (see 11.4) is reached, cool the specimen chamberat a rate of 10 6 1C/min until 10C warmer than theprogrammed expected cloud point, then adjust the cooling rateto 1.5 6 0.15C/min, while the optical system monitors forappearance of the crystals.11.7 When a cloud point is detected prema
40、turely, during thefast cooling rate, as determined by the apparatus, reheat thespecimen to a higher starting temperature, at least 30Cwarmer than the temperature of premature detection, and thencool as described in 11.5, while the optical system monitors forappearance of the crystals.11.8 At the det
41、ection of the cloud point, record the tempera-ture the specimen attained, to within 0.1C, which is held onthe digital display. Reheat the specimen to the preselectedstarting temperature.12. Report12.1 Report the temperature recorded in 11.8 to 0.1C as thecloud point D7689 (Mini Method).12.2 When spe
42、cified, correct the temperature recorded in11.8 with the relative bias in accordance with 13.3, round theresult to the next lower integer (a colder temperature), andreport as the Test Method D2500 equivalent cloud point perTest Method D7689.13. Precision and Bias513.1 PrecisionThe precision of this
43、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 using the sameapparatus under constant operating conditions on identical testmaterial, would in
44、the long run, in the normal and correctoperation of this test method, exceed Eq 1 only in one case intwenty (see Table 1).0.020630C X! valid range 250 to 16C (1)where:X = cloud point (mini method).13.1.2 ReproducibilityThe difference between two singleand independent test results, obtained by differ
45、ent operatorsworking in different laboratories on identical test material,would in the long run, in normal and correct operation of thistest method, exceed Eq 2 only in one case in twenty (see Table1).0.056130 C X! valid range 250 to 16C (2)where:X = cloud point (mini method).13.2 BiasSince there is
46、 no accepted reference materialsuitable for determining the bias for the procedure in this testmethod, bias has not been determined.13.3 Relative Bias (The degree of agreement between resultsby Test Method D7689 and Test Method D2500/IP219)Results on the same materials produced by Test Method D7689a
47、nd Test Method D2500 have been assessed in accordance withprocedures outlined in Practice D6708. The findings are:13.3.1 The degree of agreement between results from TestMethod D7689 and Test Method D2500/IP219 can be furtherimproved by applying the bias-correction outlined in Eq 3.Sample specific b
48、ias, as defined in Practice D6708, wasobserved for some samples after applying the bias correction.Bias 2 corrected X 5 predicted Y 5 X 1 1.27C (3)where:5Supporting data (the results of the 2009 Interlaboratory Cooperative TestProgram) have been filed at ASTM International Headquarters and may be ob
49、tainedby requesting Research Report RR:D02-1726.TABLE 1 Typical Repeatability and Reproducibility at VariousCloud Point (valid range -50 to +6C)Cloud Point,CRepeatability,CReproducibility,C5 0.5 1.40 0.6 1.7-5 0.7 2.0-10 0.8 2.2-15 0.9 2.5-20 1.0 2.8-25 1.1 3.1-30 1.2 3.4-35 1.3 3.6-40 1.4 3.9D7689 113X = result obtained by this Test MethodD7689, andBias - corrected X = predicted Y = result that would havebeen obtained by Test MethodD2500/IP219 on the same sample.13.3.2 Differences between bias-corrected results fr
