1、Designation: D3238 17D3238 17aStandard 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 oforiginal adopti
2、on 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*1.1 This test method covers the calculation of the carbon distribution and ri
3、ng 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 % carbon atoms in ring struc
4、ture; 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.NOTE 1The composition
5、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 carbondistribution, that is, the percent
6、age 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.1.2.1 ExceptionThe values in parentheses are for information only.1.3 This sta
7、ndard 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 safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.
8、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 World Trade Organization Technical Barriers to Tr
9、ade (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 PycnometerD1481 Test Method for Density and Rela
10、tive 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 Estimation of Mean Relative Molecular Mass of
11、 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 Fluorescence SpectrometryD4052 Test Method for D
12、ensity, Relative Density, and API Gravity of Liquids by Digital Density MeterD4294 Test Method for Sulfur in Petroleum and Petroleum Products by Energy Dispersive X-ray Fluorescence Spectrometry1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and
13、 Lubricants and is the direct responsibility of SubcommitteeD02.04.0K on Correlative Methods.Current edition approved June 1, 2017Dec. 1, 2017. Published June 2017December 2017. Originally approved in 1973. Last previous edition approved in 20152017 asD3238 95 (2015).D3238 17. DOI: 10.1520/D3238-17.
14、10.1520/D3238-17A.2 Van Nes, K., and van Westen, H. A., Aspects of the 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,
15、refer to the standards Document Summary page on the ASTM website.This document 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
16、 changes accurately, ASTM recommends that users consult prior editions 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, 10
17、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United 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
18、 and 210 F). These data are then used to calculate thecarbon distribution (% 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 pet
19、roleum. Thesedata can be used as an adjunct to the bulk properties in monitoring 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 corre
20、lated with critical product performance properties.5. Measurement of Physical 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, Test Method D1481, or Test Method D4052.5.3 Determine the average molecular
21、 weight using Test Method D2502 or Test Method D2503.6. Determination of Sulfur Content6.1 Determine the percentage of sulfur in the oil using Test Methods D1552, D2622or , or D2622D4294.7. Calculation of Carbon Distribution and Ring Content7.1 Calculate the factors v and w from the observed density
22、 (d) and the observed refractive index (n) using the followingequations:v 52.51nD2021.4750!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 v
23、13660/M (3)if v is negative:%CA 5670 v13660/M (4)7.3 Calculate the percentage of carbon 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:S = mass % sulfur.7.4 Calculate
24、 the percentage of naphthenic carbon (% CN) and the percentage of paraffinic 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 50.441
25、0.080 Mv (10)7.6 Calculate the average total number of rings per molecule (RT) 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
26、(RN) by difference:R N 5RT 2RA (13)7.8 Report ring numbers to the nearest 0.01 ring and carbon distribution to the nearest 0.1 %.D3238 17a28. 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 d
27、ifference between successive test results obtained by the same operator with the 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 i
28、n 20:Range Repeatability% CA 2.7 to 34.6 0.6% CN 23.7 to 47.2 1.2% CP 32.3 to 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 identi
29、cal test material, would, in the long run, in the normal and correct operation 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
30、3.77 0.238.2 BiasBias cannot be determined because there are no reference materials suitable for determining the bias of this testmethod.9. Keywords9.1 carbon distribution; density; molecular weight; petroleum oils; refractive index; ring contentSUMMARY OF CHANGESSubcommittee D02.04 has identified t
31、he location of selected changes to this standard since the last issue(D3238 95 (2015)D3238 17) that may impact the use of this standard. (Approved Dec. 1, 2017June 1,2017.).)(1) Added Test Method D4052D4294 to Referenced Documents.(2) Added Test Method D4052D4294 as an alternative method for density
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