1、Designation: D3238 95 (Reapproved 2015)D3238 17Standard Test Method forCalculation of Carbon Distribution and Structural GroupAnalysis of Petroleum Oils by the n-d-M Method1This standard is issued under the fixed designation D3238; the number immediately following the designation indicates the year
2、oforiginal adoption or, in the case of revision, 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.1. Scope Scope*1.1 This test method covers the calculation of the car
3、bon distribution and ring content (Note 1) of olefin-free petroleum oils frommeasurements of refractive index, density, and molecular weight (n-d-M).2 This test method should not be applied to oils whosecompositions are outside the following ranges:1.1.1 In terms of carbon distributionup to 75 % car
4、bon atoms in ring structure; percentage in aromatic rings not larger than1.5 times the percentage in naphthenic rings.1.1.2 In terms of ring contentup to four rings per molecule with not more than half of them aromatic. A correction must beapplied for oils containing significant quantities of sulfur
5、.NOTE 1The composition of complex petroleum fractions is often expressed in terms of the proportions of aromatic rings (RA), naphthene rings (RN),and paraffin chains (CP) that would comprise a hypothetical mean molecule. Alternatively, the composition may be expressed in terms of a carbondistributio
6、n, that is, the percentage of the total number of carbon atoms that are present in aromatic ring structures (% CA), naphthene ring structures (%CN), and paraffin chains (% Cp).1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.1.2
7、.1 ExceptionThe values in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applic
8、ability of regulatorylimitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the Wor
9、ld Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon LiquidsD1480 Test Method for Density and Relative Density (Specific Gravity) of Viscous Materials by Bingham Py
10、cnometerD1481 Test Method for Density and Relative Density (Specific Gravity) of Viscous Materials by Lipkin Bicapillary PycnometerD1552 Test Method for Sulfur in Petroleum Products by High Temperature Combustion and Infrared (IR) Detection or ThermalConductivity Detection (TCD)D2502 Test Method for
11、 Estimation of Mean Relative Molecular Mass of Petroleum Oils from Viscosity MeasurementsD2503 Test Method for Relative Molecular Mass (Molecular Weight) of Hydrocarbons by Thermoelectric Measurement ofVapor PressureD2622 Test Method for Sulfur in Petroleum Products by Wavelength Dispersive X-ray Fl
12、uorescence SpectrometryD4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.04.0K o
13、n Correlative Methods.Current edition approved Oct. 1, 2015June 1, 2017. Published December 2015June 2017. Originally approved in 1973. Last previous edition approved in 20102015 asD3238 95 (2010).(2015). DOI: 10.1520/D3238-95R15.10.1520/D3238-17.2 Van Nes, K., and van Westen, H. A., Aspects of the
14、Constitution of Mineral Oils, Elsevier, New York, 1951.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This d
15、ocument is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions
16、as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Uni
17、ted States13. Summary of Test Method3.1 The refractive index and density of the oil are determined at 20 C. The molecular weight is determined experimentally orestimated from measurements of viscosity at 37.8 C and 98.89 C (100 F and 210 F). These data are then used to calculate thecarbon distributi
18、on (% CA, % CN, % CP) or the ring analysis (RA, RN) using the appropriate set of equations.4. Significance and Use4.1 The carbon distribution and ring content serve to express the gross composition of the heavier fractions of petroleum. Thesedata can be used as an adjunct to the bulk properties in m
19、onitoring the manufacture of lubricating oil base stocks by distillation,solvent refining or hydrogenation, or both, and in comparing the composition of stocks from different crude sources. Furthermore,the data can often be correlated with critical product performance properties.5. Measurement of Ph
20、ysical Properties5.1 Determine the refractive index of the oil at 20 C using Test Method D1218.5.2 Determine the density at 20 C using Test Method D1480 or , Test Method D1481, or Test Method D4052.5.3 Determine the average molecular weight using Test Method D2502 or Test Method D2503.6. Determinati
21、on of Sulfur Content6.1 Determine the percentage of sulfur in the oil using Test Methods D1552 or D2622.7. Calculation of Carbon Distribution and Ring Content7.1 Calculate the factors v and w from the observed density (d) and the observed refractive index (n) using the followingequations:v 52.51nD20
22、21.4750!2d 42020.8510! (1)w 5d42020.8510!21.11nD2021.4750! (2)7.2 Calculate the percentage of aromatic carbon (% CA) from v and the molecular weight (M) using one of the followingequations:if v is positive:% CA 5430 v13660/M (3)if v is negative:%CA 5670 v13660/M (4)7.3 Calculate the percentage of ca
23、rbon in total (aromatic and naphthenic) ring structures (% CR) from w and the molecularweight.if w is positive:%CR 5820 w 23S110000/M (5)if w is negative:%CR 51440w 23S110600/M (6)where:where:S = mass % sulfur.7.4 Calculate the percentage of naphthenic carbon (% CN) and the percentage of paraffinic
24、carbon (% CP) as follows:%CN 5%CR 2%CA (7)%CP 51002%CR (8)7.5 Calculate the average number of aromatic rings per molecule (RA) from v and the molecular weight:if v is positive:RA 50.4410.055 Mv (9)if v is negative:RA 50.4410.080 Mv (10)7.6 Calculate the average total number of rings per molecule (RT
25、) from w and the molecular weight:if w is positive:RT 51.3310.146 M w 20.005 S! (11)if w is negative:RT 51.3310.180 M w 20.005 S! (12)where:S = mass % sulfur.7.7 Calculate the average number of naphthene rings per molecule (RN) by difference:R N 5RT 2RA (13)7.8 Report ring numbers to the nearest 0.0
26、1 ring and carbon distribution to the nearest 0.1 %.D3238 1728. Precision and Bias8.1 The precision of this test as obtained by statistical examination of interlaboratory test results is as follows:8.1.1 RepeatabilityThe difference between successive test results obtained by the same operator with t
27、he same apparatusunder constant operating conditions on identical test material would, in the long run, in the normal and correct operation of thetest method, exceed the values shown in the following table only in 1 case in 20:Range Repeatability% CA 2.7 to 34.6 0.6% CN 23.7 to 47.2 1.2% CP 32.3 to
28、68.6 1.0RA 0.12 to 1.69 0.04RN 1.61 to 2.90 0.08RT 1.73 to 3.77 0.088.1.2 ReproducibilityThe difference between two single and independent results, obtained by different operators working indifferent laboratories on identical test material, would, in the long run, in the normal and correct operation
29、 of the test method,exceed the values shown in the following table only in 1 case in 20:Range Reproducibility% CA 2.7 to 34.6 1.7% CN 23.7 to 47.2 3.6% CP 32.3 to 68.6 3.4RA 0.12 to 1.69 0.09RN 1.61 to 2.90 0.23RT 1.73 to 3.77 0.238.2 BiasBias cannot be determined because there are no reference mate
30、rials suitable for determining the bias of this testmethod.9. Keywords9.1 carbon distribution; density; molecular weight; petroleum oils ; oils; refractive index; ring contentSUMMARY OF CHANGESSubcommittee D02.04 has identified the location of selected changes to this standard since the last issue(D
31、3238 95 (2015) that may impact the use of this standard. (Approved June 1, 2017.)(1) Added Test Method D4052 to Referenced Documents.(2) Added Test Method D4052 as an alternative method for density measurement in subsection 5.2, Measurement of PhysicalProperties.ASTM International takes no position
32、respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.Th
33、is standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Inte
34、rnational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown
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