1、Designation: D7397 10Standard Test Method forCloud Point of Petroleum Products (Miniaturized OpticalMethod)1This standard is issued under the fixed designation D7397; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the cloudpoint of petroleum products and biodiesel fuels that aretransparent
3、 in layers 40 mm in thickness by an automaticinstrument.1.2 This test method covers the range of temperatures from60 to +20C with temperature resolution of 0.1C; however,the range of temperatures included in the 2006 interlaboratorycooperative test program only covered the temperature range of35 to
4、+12C. See Section 13.1.3 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 address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this stand
5、ard 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 Test Method for Cloud Point of Petroleum ProductsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD41
6、77 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5773 Test Method for Cloud Point of Petroleum Products(Constant Cooling Rate Method)2.2 Energy Institute Standards:3IP 219 Test Method for Cloud Point of Petroleum ProductsIP 446 Test Method for Cloud Point of Petroleum Products3.
7、 Terminology3.1 Definitions:3.1.1 biodiesel, nfuel comprising mono-alkyl esters oflong-chain fatty acids derived from vegetable oils or animalfats, designated B100.3.1.1.1 DiscussionBiodiesel is typically produced by areaction of vegetable oil or animal fat with an alcohol such asmethanol or ethanol
8、 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 blend (BXX), nblend of biodiesel fuel withpetroleum-based diesel fuel designated
9、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 temperature of a liquid specimen when the smallestobservable cluster of hydrocarbon crystals first occurs uponcooling under prescribed c
10、onditions.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 liquid, the cloud isalways noted first at the location in the specimen where thespecimen temperature is the lowest. The cloud point is
11、thetemperature at which the crystals first occur, regardless of theirlocation 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 cr
12、ystals.”3.2 Definitions of Terms Specific to This Standard: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 May 1, 2010. Published August 2010. Orig
13、inallyapproved in 2007. Last previous edition approved in 2008 as D739708. DOI:10.1520/D7397-10.2For 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 Docume
14、nt Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.uk.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 1942
15、8-2959, United States.3.2.1 D2500/IP 219 equivalent cloud point, ntemperatureof a specimen, in integers, calculated by applying a bias androunding the result to the next lower integer (see 12.2).3.2.1.1 DiscussionThis test method produces results with0.1C resolution. Should the user wish to provide
16、results witha similar format to Test Method D2500, then this calculationcan be performed (see 12.2). Some apparatus can perform thiscalculation automatically.3.2.2 automatic cloud point, ntemperature of a specimen,when the appearance of the cloud is determined under theconditions of this test method
17、.3.2.2.1 DiscussionThe cloud point in this test method isdetermined by an automatic instrument using a miniaturizedtest receptacle equipped with two optical fibers, one to bringlight into the test receptacle and the other to receive lightscattered from the specimen.3.2.3 miniaturized optical method,
18、 nin cloud point testmethods, test procedure using prescribed cooling rate, speci-men receptacle, and optical system for detection of crystalformation.3.2.3.1 DiscussionThe prescribed cooling rate is de-scribed in 4.1, the specimen receptacle is described in AnnexA1, and the optical system for the d
19、etection of crystal forma-tion is described in Annex A1.3.2.4 Peltier device, nsolid state thermoelectric deviceconstructed with dissimilar semiconductor materials and con-figured in such a way that it will transfer heat to or away froma test specimen dependent on the direction of electric currentap
20、plied to the device.44. Summary of Test Method4.1 A specimen is cooled by a Peltier device in a miniatur-ized specimen receptacle (A1.1.1) at a rate of 30 6 5C/min,while continuously being illuminated by a light source(A1.1.4). The specimen is continuously monitored by anoptical detector (A1.1.5) fo
21、r the first appearance of a cloud ofwax crystals. Once crystals are first detected, as manifested byan increase in scattered light level received by the opticaldetector, the specimen is warmed at a rate of 15 6 5C/min.Assoon as all the crystals have re-dissolved into the liquidspecimen, warming is h
22、alted and the specimen is cooled again;but this time at a slower rate of 6 6 3C/min. When crystalsfirst appear under this slower cooling rate, the temperature ofthe specimen is recorded to 0.1C resolution as cloud point.5. Significance and Use5.1 The cloud point of petroleum products and biodieselfu
23、els 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 a precise mea-surement of the cloud point.5.3 This test method can determine the temperature of
24、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 are equivalent toTest Method D5773/IP 446. The temperature results of this testmethod have been found to be warmer than those of TestMethod D2
25、500/IP 219 by an average of 0.49C; however, nosample specific bias was observed.5.5 Similar to Test Method D5773/IP 446, this test methoddetermines cloud point in a shorter period of time than TestMethod D2500/IP 219.NOTE 1In cases of samples with cloud points near ambient tempera-tures, time saving
26、s may not be realized.NOTE 2This test method eliminates most of the operator timerequired of Test Method D2500/IP 219.NOTE 3The only utility required by the apparatus described in thistest method is electricity with power consumption of approximately 20watts. The electric power can come from an alte
27、rnating current source(wall receptacle) or direct current source such as a battery or a cigarettelighter plug in a vehicle.NOTE 4The apparatus described by this test method can be mademuch smaller and lighter than that of Test Methods D5773/IP 446 andD2500/IP 219, allowing full portability.NOTE 5The
28、 apparatus used in the 2006 interlaboratory study weighedapproximately 1 kg and occupied the space of a small lunch box. SeeSection 13.6. Apparatus6.1 Automatic Apparatus4,5The automatic cloud pointapparatus described in this test method consists of a testchamber controlled by a microprocessor that
29、is capable ofcontrolling the heating and cooling of the test specimen,optically observing the first appearance of a cloud of waxcrystals and recording the temperature of the specimen de-scribed in detail in Annex A1.6.2 The apparatus shall be equipped with a specimenreceptacle, optical detector, lig
30、ht source, optical fibers, digitaldisplay, Peltier device, and a specimen temperature measuringdevice.6.3 The Peltier device shall be capable of heating or coolingthe test specimen at a rate of 3 to 35C/min.6.4 The temperature measuring device in the specimenreceptacle shall be capable of measuring
31、the temperature of thetest specimen from 60 to +20C at a resolution of 0.1C.4NOTE 6The apparatus described above is covered by patents. If youare aware of an alternative(s) to the patented items, please attach to yourballot return a description of the alternative(s). All suggestions will beconsidere
32、d by the committee.7. Reagents and Materials7.1 Disposable syringe that is capable of dispensing at least10 6 0.5 mL per full discharge of sample into the specimenreceptacle.4The Peltier device is covered by a patent. Interested parties are invited to submitinformation regarding the identification o
33、f an alternative(s) to this patented item tothe ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the responsible technical committee.5The sole source of supply of the apparatus known to the committee at this timeis Phase Technology Miniature Cloud Po
34、int Analyzer available from PhaseTechnology, 11168 Hammersmith Gate, Richmond, B.C., Canada V7A-5H8. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical
35、committee,1which you may attend.D7397 102NOTE 7The apparatus can also be connected to a sample supply lineto receive new sample. The amount of sample required per analysis is thesame as that for the syringe injection procedure (that is, 20 6 1.0 mL peranalysis). In such cases, a disposable syringe w
36、ould not be needed.8. Sampling8.1 Obtain a sample in accordance with Practices D4057 orD4177.8.2 Samples of very viscous materials may be warmed untilthey are reasonably fluid before they are tested. However, nosample should be heated more than absolutely necessary.8.3 The sample shall not be heated
37、 above 70C. When thesample is heated above 70 C, allow the sample to cool below70C before filtering or inserting into the apparatus.8.4 When moisture is present in the sample, remove themoisture by a method, such as filtration through dry lint-freefilter paper, until the specimen is perfectly clear,
38、 but make suchfiltration at a temperature at least 14C above the expectedcloud point.NOTE 8Moisture 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.
39、1 Prepare the instrument for operation in accordance withthe manufacturers instructions.9.2 Turn on the main power switch of the analyzer.10. Calibration and Standardization10.1 Ensure that all of the manufacturers instructions forcalibrating, checking, and operating the apparatus are fol-lowed.10.2
40、 A sample with a mutually agreed upon cloud point canbe used to verify performance of the apparatus.11. Procedure11.1 Draw 10 6 0.5 mL of bubble-free sample into a newdisposable syringe. Connect the syringe to the inlet port, andinject the full charge of sample into the test receptacle. Thespecimen
41、excess will flow into a waste-receiving container.11.2 Draw another 10 6 0.5 mL of bubble-free sample intothe syringe. Connect the syringe to the inlet port, and inject thefull charge of sample into the test receptacle. The specimenexcess will flow into a waste-receiving container. The totalamount o
42、f sample (that is, 20 6 1.0 mL) is sufficient inquantity to flush out any previous sample in the specimenreceptacle and fill it with the fresh sample.NOTE 9Follow manufacturers instructions for sample injection if thespecimen receptacle is connected to a sample supply line as described inNote 7.11.3
43、 Start the operation of the apparatus according to themanufacturers instructions. From this point on, the apparatusautomatically controls the procedure.11.4 Cool the sample at a rate of 30 6 5C/min, whilecontinuously illuminating the sample with the light source.Monitor the specimen continuously wit
44、h the optical detector.Once crystals are first detected, as manifested by an increase inlight level received by the optical detector, warm the specimenat a rate of 15 6 5C/min. As soon as all the crystals havere-dissolved into the liquid specimen in accordance with thistest method, stop the warming
45、and cool the specimen again ata slower rate of 6 6 3C/min. When crystals first appear underthis slower cooling rate, record the temperature of the speci-men as the cloud point.11.5 The measurement is automatically terminated once thecloud point is detected.11.6 When the measurement is complete, the
46、cloud pointvalue per Test Method D7397 will be displayed by theapparatus.12. Calculation or Interpretation of Results12.1 Report the temperature recorded in 11.6 as the auto-matic cloud point Test Method D7397.12.2 When specified, correct the temperature recorded in11.6 with the relative bias in acc
47、ordance with 13.3, round theresult to the next lower integer (a colder temperature), andreport as the Test Method D2500/IP 219 equivalent cloud pointper Test Method D7397.13. Precision and Bias613.1 PrecisionThe precision of this test method as deter-mined by the statistical examination of the inter
48、laboratory 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 the long run, in the normal and correctoperation of this test method,
49、exceed:0.26E201 3 31.0 X!Cwhere X = cloud point in C only in one case in twenty. SeeTable 1.13.1.2 ReproducibilityThe difference between two singleand independent 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:0.34E201 3 31.0 X!Cwhere X = cloud point in C) only in one case in twenty. SeeTable 2.6Supporting data (the results of the 2006 Interlaboratory Cooperative TestProgram) have be
