1、Designation: D6749 02 (Reapproved 2018)Standard Test Method forPour Point of Petroleum Products (Automatic Air PressureMethod)1This standard is issued under the fixed designation D6749; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year 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.INTRODUCTIONThis test method covers an alternative procedure for the determination of pour point of petroleumproduc
3、ts using an automatic apparatus.1. Scope1.1 This test method covers the determination of pour pointof petroleum products by an automatic apparatus that applies aslightly positive air pressure onto the specimen surface whilethe specimen is being cooled.1.2 This test method is designed to cover the ra
4、nge oftemperatures from 57 C to +51 C; however, the range oftemperatures included in the (1998) interlaboratory test pro-gram only covered the temperature range from 51 C to11 C.1.3 Test results from this test method can be determined ateither 1 C or 3 C testing intervals.1.4 This test method is not
5、 intended for use with crude oils.NOTE 1The applicability of this test method on residual fuel sampleshas not been verified. For further information on the applicability, refer to13.4.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thiss
6、tandard.1.6 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prio
7、r to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBa
8、rriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D97 Test Method for Pour Point of Petroleum ProductsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum Products2.2 Energy Institute Standard:IP
9、 15 Test Method for Pour Point of Petroleum Products33. Terminology3.1 Definitions:3.1.1 pour point, nin petroleum products, lowest tempera-ture at which movement of the test specimen is observed underprescribed conditions of test.3.2 Definitions of Terms Specific to This Standard:3.2.1 air pressure
10、, nregulated slightly positive air pres-sure gently applied onto the specimen surface in the airtighttest jar that causes upward movement of the specimen in thecommunicating tube, which has one end inserted into the testspecimen and the other end at atmospheric pressure.3.2.2 no-flow point, nin petr
11、oleum products, temperatureof the test specimen at which a wax crystal structure of the testspecimen or viscosity increase, or both, impedes movement ofthe surface of the test specimen under the conditions of the test.3.2.2.1 DiscussionThe no-flow point occurs when, uponcooling, the formation of wax
12、 crystal structures or viscosityincrease, or both, has progressed to the point where the appliedobservation device no longer detects movement under the1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility
13、 ofSubcommittee D02.07 on Flow Properties.Current edition approved May 1, 2018. Published June 2018. Originallyapproved in 2002. Last previous edition approved in 2012 as D6749 02 (2012).DOI: 10.1520/D6749-02R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cus
14、tomer 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, W1G 7AR,U.K., http:/www.energyinst.org.Copyright ASTM International, 100 Barr Harbor
15、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 and Recommendations
16、 issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1conditions of the test. The preceding observation temperature,at which flow of the test specimen is last observed, is the pourpoint.4. Summary of Test Method4.1 After inserting the test jar containing the specimen i
17、ntothe automatic pour point apparatus and initiating the testprogram, the specimen is automatically heated to the desig-nated temperature and then cooled at a controlled rate. Attemperature intervals of 1 C or 3 C, depending on theselection made by the user prior to the test, a slightly positiveair
18、pressure is gently applied onto the surface of the specimenwhich is contained in an airtight test jar equipped with acommunicating tube. Since one end of the communicating tubeis inserted into the specimen while the other end is maintainedat atmospheric pressure, a small amount of downward move-ment
19、 or deformation of the specimen surface, as a result of theapplication of air pressure, is observed by means of upwardmovement of the specimen in the communicating tube. Thisupward movement of the specimen is detected by a pressuresensor which is installed at the atmospheric end of thecommunicating
20、tube. The lowest temperature at which defor-mation of the specimen is observed upon application of airpressure is recorded as the pour point in accordance with TestMethod D6749.5. Significance and Use5.1 The pour point of a petroleum product is an index of thelowest temperature of its utility for ce
21、rtain applications. Flowcharacteristics, like pour point, can be critical for the correctoperation of lubricating systems, fuel systems, and pipelineoperations.5.2 Petroleum blending operations require precise measure-ment of the pour point.5.3 Test results from this test method can be determined at
22、either 1 C or 3 C intervals.5.4 This test method yields a pour point in a format similarto Test Method D97/IP 15 when the 3 C interval results arereported. However, when specification requires Test MethodD97/IP 15, do not substitute this test method.NOTE 2Since some users may wish to report their re
23、sults in a formatsimilar to Test Method D97/IP 15 (in 3 C intervals), the precision datawere derived for the 3 C intervals. For statements on bias relative to TestMethod D97/IP 15, see 13.3.1.5.5 This test method has better repeatability and reproduc-ibility relative to Test Method D97/IP 15 as meas
24、ured in the1998 interlaboratory test program (see Section 13).6. Apparatus6.1 Automatic Apparatus4,5The automatic pour point ap-paratus described in this test method is a microprocessorcontrolled apparatus that is capable of heating and cooling aspecimen, applying air pressure onto the specimens sur
25、face,detecting the specimens surface movement, and then comput-ing and reporting the pour point (see Fig. 1). The detail isdescribed in Annex A1.6.2 Test Jar, clear cylindrical glass with a flat bottom withan approximate capacity of 12 mL. Approximately 4.5 mL ofsample specimen is contained when fil
26、led to the scribed line.The test jar is fitted with a test jar cap assembly on its top toform an air chamber over the test specimen.6.3 Test Jar Cap AssemblyAplastic cap is installed on topof the test jar with the provision of sealing air.Aglass tube witha metallic tip shall be inserted from underne
27、ath the plastic capinto the round hole in the center of the test jar cap. The top endof the round hole is connected to an air pressure sensor by wayof a vinyl tube. To supply air pressure to the specimenssurface, a vinyl tube connected to an air syringe is locatedadjacent to the glass tube through a
28、n orifice in the plastic cap.When a specimen is to be tested, the test jar cap assembly isinstalled on the test jar with the lower end of the glass tube4The sole source of supply of the apparatus known to the committee at this timeis Tanaka model MPC series Pour Point Analyzers available from Tanaka
29、 ScientificLimited, Adachiku, Tokyo, Japan. Various models included in this model series aredifferentiated by their cooling capacities or number of test heads, or both. If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will r
30、eceive careful consideration at a meetingof the responsible technical committee,1which you may attend.5This pour point analyzer is covered by a patent. If you are aware of analternative(s) to the patented item, please attach to your ballot return a descriptionof the alternatives. All the suggestions
31、 will be considered by the committee.FIG. 1 Automatic ApparatusD6749 02 (2018)2inserted into the specimen in the test jar. The glass tube and thetest jar form a communicating tube. A temperature sensor in asmall diameter metallic sheath shall be installed in the center ofthe glass tube.6.4 Metallic
32、Block Bath, a metallic block with a cylindricalhole to 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 Agents, capable of cleaning and dry
33、ing the testjar, temperature sensor, and glass tube after each test. Chemicalagents such as alcohol, petroleum-based solvents, and acetonehave been found suitable to use. (WarningFlammable.)(WarningMay be harmful by itself or when evaporated.)8. Sampling8.1 Obtain a sample in accordance with Practic
34、e D4057 orby Practice D4177.8.2 Samples of very viscous materials may be warmed untilthey are reasonably fluid before they are transferred; however,no sample shall be heated more than is absolutely necessary.The sample shall not be heated and transferred into the test jarunless its temperature is 70
35、 C or lower.NOTE 3In the event the sample has been heated above thistemperature, allow the sample to cool until its temperature is at least 70 Cbefore transferring.9. Preparation of Apparatus9.1 Install the automatic apparatus for operation in accor-dance with the manufacturers instructions.9.2 Clea
36、n and dry the test jar, temperature sensor, and glasstube.9.3 Turn on the main power switch of the automaticapparatus.10. Calibration and Standardization10.1 Ensure that all of the manufacturers instructions forcalibrating, checking, and operating the automatic apparatusare followed.10.2 Check the p
37、osition of the temperature sensor and glasstube according to the manufacturers instructions and, whennecessary, make appropriate adjustments.10.3 A sample with a well documented pour point can beused to verify the performance of the automatic apparatus.Alternatively, a sample which has been extensiv
38、ely tested in apour point interlaboratory study can be used.11. Procedure11.1 Pour the sample specimen into the test jar to the scribedmark. When necessary, heat the sample in a bath or oven untilit is just sufficiently fluid to pour into the test jar. Samples withan expected pour point above 36 C o
39、r samples which appearsolid at room temperature can be heated above 45 C, but shallnot be heated above 70 C.11.2 Insert the charged test jar into the metallic block bathand install the test jar cap assembly snugly.11.3 Select the desired test mode, including the pour pointtesting interval, according
40、 to the manufacturers instructions.Should the user wish to provide results with a similar format toTest Method D97/IP 15, then testing at a 3 C interval shall beselected. Start the automatic sample preheating function, andthen enter the expected pour point (EPP). When the 3 Ctesting interval is chos
41、en, the EPP needs to be a multiple of3 C.11.4 Start the test program. The sample is automaticallypreheated by the automatic apparatus to 45 C or to EPP+ 9C,whichever is higher, but no higher than 70 C, by maintainingthe bath temperature at 48 C or EPP + 12 C, whichever ishigher.11.5 After the prehea
42、ting is completed, the specimen iscooled down automatically.11.5.1 The metallic block bath is cooled down at a rate of3 Cmin to 4 Cmin, to the EPP + 40 C.11.5.2 From the EPP + 40 C to the no-flow point, themetallic block bath is cooled at a rate of 0.8 Cmin to1.1 Cmin.11.6 As the specimen temperatur
43、e reaches a predeterminedtemperature, which is dependent on the EPP, the automaticapparatus starts testing for no-flow state by applying airpressure to the specimen surface at the programmed testinginterval. When the specimen is still in a fluid state, thespecimen level moves up in the glass tube as
44、 air pressure isapplied on the specimen surface; when the specimen reaches ano-flow state, the specimen level does not move at all in theglass tube. Upon detecting the no-flow point, the automaticapparatus computes and displays the pour point, which is thesum of the no-flow point temperature and the
45、 testing interval.Also, the automatic apparatus stops cooling and starts heatingthe specimen.11.6.1 Specimen Having Expected Pour Point Equal To orAbove +36 CThe automatic apparatus starts testing for theno-flow state at EPP + 9 C.11.6.2 Specimen Having Expected Pour Point Equal To orBetween +31 C a
46、nd +35 CThe automatic apparatus startstesting for the no-flow state at 45 C.11.6.3 Specimen Having Expected Pour Point Equal To orBelow +30 CThe automatic apparatus starts testing for theno-flow state at EPP + 15 C.11.7 Remove the test jar cap assembly and clean the test jarand test jar cap assembly
47、.NOTE 4Residual fuels have been known to be sensitive to thermalhistory. In the case where a residual fuel sample is tested, refer to TestMethod D97 for sample treatment.12. Report12.1 Report the temperature recorded in 11.6 and the testinginterval as the pour point in accordance with Test MethodD67
48、49.D6749 02 (2018)313. Precision and Bias613.1 PrecisionThe precision of this test method as deter-mined by statistical examination of interlaboratory test resultsis as follows:13.1.1 Pour Point at 3 C Testing Intervals (Test MethodD6749):13.1.1.1 RepeatabilityThe difference between successivetest r
49、esults, 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, exceed the following, only in onecase in twenty.2.5 C13.1.1.2 ReproducibilityThe difference between twosingle and independent test results, obtained by differentoperators working in different laboratories on identical testmaterial, would in the long run, in normal and correct operationof this test method,
