1、Designation: D6749 02 (Reapproved 2012)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 to +51C; however, the range oftemperatures included in the (1998) interlaboratory test pro-gram only covered the temperature range from 51 to 11C.1.3 Test results from this test method can be determined ateither 1 or 3C testing intervals.1.4 This test method is not intende
5、d 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 thisstandard.
6、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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced D
7、ocuments2.1 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 15 Test Method for Pour Point of Petroleum Pro
8、ducts33. 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, nregulated slightly positive air pres-sure ge
9、ntly 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 petroleum products, temperatureof the test specimen
10、 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 crystal structures or viscosityincrease, or bo
11、th, has progressed to the point where the appliedobservation device no longer detects movement under theconditions 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 contai
12、ning the specimen intothe automatic pour point apparatus and initiating the test1This 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 Nov. 1, 2012. Publi
13、shed November 2012. Originallyapproved in 2002. Last previous edition approved in 2007 as D674902 (2007).DOI: 10.1520/D6749-02R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informat
14、ion, 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1program, th
15、e specimen is automatically heated to the desig-nated temperature and then cooled at a controlled rate. Attemperature intervals of 1 or 3C, depending on the selectionmade by the user prior to the test, a slightly positive airpressure is gently applied onto the surface of the specimenwhich is contain
16、ed 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 or deformation of the specimen surface, as a result of theapplication of a
17、ir 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 tube. The lowest temperature at which defor-mation of the specimen is obser
18、ved 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 certain applications. Flowcharacteristics, like pour point, can be critical f
19、or 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 ateither 1 or 3C intervals.5.4 This test method yields a pour point in a form
20、at similarto Test Method D97/IP 15 when the 3C 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 results in a formatsimilar to Test Method D97/IP 15 (in 3C intervals), the precis
21、ion datawere derived for the 3C 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 measured in the1998 interlaboratory test program (see Section 13).6. Apparatus6.1 Aut
22、omatic 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 surface,detecting the specimens surface movement, and then comput-ing and reporting
23、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 filled to the scribed line.The test jar is fitted with a test jar cap assembly on it
24、s 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 underneath the plastic capinto the round hole in the center of the test jar cap. The top
25、 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 an orifice in the plastic cap.When a specimen is to be tested, the test jar cap as
26、sembly isinstalled on the test jar with the lower end of the glass tubeinserted 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 Block Ba
27、th, a metallic block with a cylindricalhole to fit the test jar. The metallic block assembly shall have4The sole source of supply of the apparatus known to the committee at this timeis Tanaka model MPC series Pour Point Analyzers available from Tanaka ScientificLimited, Adachiku, Tokyo, Japan. Vario
28、us 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 receive careful consideration at a meetingof the r
29、esponsible 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 will be considered by the committee. FIG. 1 Auto
30、matic ApparatusD6749 02 (2012)2a 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 drying the testjar, temperature sensor, and glass tube after each test. Chemicalage
31、nts 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 Practice D4057 orby Practice D4177.8.2 Samples of very viscous materials may be warmed
32、 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 70C or lower.NOTE 3In the event the sample has been heated above thistemperature,
33、 allow the sample to cool until its temperature is at least 70Cbefore transferring.9. Preparation of Apparatus9.1 Install the automatic apparatus for operation in accor-dance with the manufacturers instructions.9.2 Clean and dry the test jar, temperature sensor, and glasstube.9.3 Turn on the main po
34、wer 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 position of the temperature sensor and glasstube according to the manufacturers in
35、structions 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 extensively tested in apour point interlaboratory study can be used.11. Procedure11.1 Pou
36、r 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 36C or samples which appearsolid at room temperature can be heated above 45C, but shall
37、not be heated above 70C.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 to the manufacturers instructions.Should the user wish to provide results with a si
38、milar format toTest Method D97/IP 15, then testing at a 3C interval shall beselected. Start the automatic sample preheating function, andthen enter the expected pour point (EPP). When the 3C testinginterval is chosen, the EPP needs to be a multiple of 3C.11.4 Start the test program. The sample is au
39、tomaticallypreheated by the automatic apparatus to 45C or to EPP + 9C,whichever is higher, but no higher than 70C, by maintainingthe bath temperature at 48C or EPP + 12C, whichever ishigher.11.5 After the preheating is completed, the specimen iscooled down automatically.11.5.1 The metallic block bat
40、h is cooled down at a rate of 3to 4C/min, to the EPP + 40C.11.5.2 From the EPP + 40C to the no-flow point, themetallic block bath is cooled at a rate of 0.8 to 1.1C/min.11.6 As the specimen temperature reaches a predeterminedtemperature, which is dependent on the EPP, the automaticapparatus starts t
41、esting 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 air pressure isapplied on the specimen surface; when the specimen reaches ano-flow state, the speci
42、men 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 t97hesum of the no-flow point temperature and the testing interval.Also, the automatic apparatus stops cooling and starts heatingthe specimen.11.6.
43、1 Specimen Having Expected Pour Point Equal To orAbove +36CThe automatic apparatus starts testing for theno-flow state at EPP + 9C.11.6.2 Specimen Having Expected Pour Point Equal To orBetween +31C and +35CThe automatic apparatus startstesting for the no-flow state at 45C.11.6.3 Specimen Having Expe
44、cted Pour Point Equal To orBelow +30CThe automatic apparatus starts testing for theno-flow state at EPP + 15C.11.7 Remove the test jar cap assembly and clean the test jarand test jar cap assembly.NOTE 4Residual fuels have been known to be sensitive to thermalhistory. In the case where a residual fue
45、l 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 MethodD6749.13. Precision and Bias613.1 PrecisionThe precision of this test method as deter-mined by statistical e
46、xamination of interlaboratory test resultsis as follows:13.1.1 Pour Point at 3C Testing Intervals (Test MethodD6749):13.1.1.1 RepeatabilityThe difference between successivetest results, obtained by the same operator using the same6Supporting data have been filed at ASTM International Headquarters an
47、d maybe obtained by requesting Research Report RR:D02-1499.D6749 02 (2012)3apparatus 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.2.5C13.1.1.2 Reproducibil
48、ityThe 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, exceed the following, only in one case intwenty.3.1C13.1.2 Pour Poi
49、nt at 1C Testing Intervals (Test MethodD6749):13.1.2.1 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, exceed the following, only in onecase in twenty.1.1C13.1.2.2 ReproducibilityThe difference between twosingle and independent test results, obtained by differentoperators working in different laboratories on id
