1、Designation: D 6749 02 (Reapproved 2007)An American National StandardStandard Test Method forPour Point of Petroleum Products (Automatic Air PressureMethod)1This standard is issued under the fixed designation D 6749; the number immediately following the designation indicates the year oforiginal adop
2、tion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method covers an alternative procedure for the determination
3、of pour point of petroleumproducts 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 me
4、thod is designed to cover the range 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
5、 This test method is not 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 measureme
6、nt are included in thisstandard.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 limitati
7、ons prior to use.2. Referenced Documents2.1 ASTM Standards:2D97 Test Method for Pour Point of Petroleum ProductsD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum Products2.2 Energy Institute Standard:IP 15 Test Meth
8、od 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, nregulated
9、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 petroleum product
10、s, 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 crystal stru
11、ctures or viscosityincrease, or both, 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 A
12、fter inserting the test jar containing the specimen intothe 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 or 3C, depending on the selectionmade by t
13、he user prior to the test, a slightly positive air1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.07.0D on Wax-Related Viscometric Properties of Fuels and Oils.Current edition approved Aug. 1, 2
14、007. Published September 2007. Originallyapproved in 2002. Last previous edition approved in 2002 as D 674902.2For 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 st
15、andards Document Summary page onthe ASTM website.3Available 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.pressure is gently applied ont
16、o 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 or deformation of the specime
17、n 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 tube. The lowest temperature a
18、t which defor-mation of the specimen is observed upon application of airpressure is recorded as the pour point in accordance with TestMethod D 6749.5. Significance and Use5.1 The pour point of a petroleum product is an index of thelowest temperature of its utility for certain applications. Flowchara
19、cteristics, 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 ateither 1 or 3C intervals.5.4
20、This test method yields a pour point in a format 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
21、Method D97/IP 15 (in 3C intervals), the precision 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 tes
22、t 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 surface,detecting the specimens surfac
23、e 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 filled to the scribed line.The test ja
24、r 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 underneath the plastic capinto the round h
25、ole 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 an orifice in the plastic cap.When a
26、 specimen is to be tested, the test jar cap assembly 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
27、 center ofthe glass tube.6.4 Metallic 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 Cleani
28、ng Agents, capable of cleaning and drying the testjar, temperature sensor, and glass tube after each test. Chemicalagents such as alcohol, petroleum-based solvents, and acetone4The sole source of supply of the apparatus known to the committee at this timeis Tanaka model MPC series Pour Point Analyze
29、rs available from Tanaka 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 Headquarte
30、rs. Your comments will receive 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 alternati
31、ves. All the suggestions will be considered by the committee.FIG. 1 Automatic ApparatusD 6749 02 (2007)2have been found suitable to use. (WarningFlammable.)(WarningMay be harmful by itself or when evaporated.)8. Sampling8.1 Obtain a sample in accordance with Practice D 4057 orby Practice D 4177.8.2
32、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 70C or lower.NOTE 3In the event th
33、e sample has been heated above this tempera-ture, allow the sample to cool until its temperature is at least 70C beforetransferring.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, temperat
34、ure 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 position of the temperature senso
35、r 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 extensively tested in apour point interl
36、aboratory 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 36C or samples which appearsolid at ro
37、om temperature can be heated above 45C, but shallnot 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.
38、Should the user wish to provide results with a similar 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
39、 3C.11.4 Start the test program. The sample is automaticallypreheated 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
40、 down automatically.11.5.1 The metallic block bath 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 depe
41、ndent 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 air pressure isapplied on the specimen surface; wh
42、en 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 t97hesum of the no-flow point temperature and the testing interval.Also, the automatic apparatus s
43、tops cooling and starts heatingthe specimen.11.6.1 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
44、 no-flow state at 45C.11.6.3 Specimen Having Expected 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
45、 thermalhistory. In the case where a residual fuel sample is tested, refer to TestMethod D97for sample treatment.12. Report12.1 Report the temperature recorded in 11.6 and the testinginterval as the pour point in accordance with Test MethodD 6749.13. Precision and Bias613.1 PrecisionThe precision of
46、 this test method as deter-mined by statistical examination of interlaboratory test resultsis as follows:13.1.1 Pour Point at 3C Testing Intervals (Test MethodD 6749):13.1.1.1 RepeatabilityThe difference between successivetest results, obtained by the same operator using the sameapparatus under cons
47、tant 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 ReproducibilityThe difference between twosingle and independent test results, obtained by differentoperator
48、s working in different laboratories on identical test6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D02-1499.D 6749 02 (2007)3material, would in the long run, in normal and correct operationof this test method, exceed the foll
49、owing, only in one case intwenty.3.1C13.1.2 Pour Point at 1C Testing Intervals (Test MethodD 6749):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 differ
