1、Designation: D3238 95 (Reapproved 2010)Standard 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 oforigin
2、al 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. Scope1.1 This test method covers the calculation of the carbondistribution
3、 and ring content (Note 1) of olefin-free petroleumoils from measurements of refractive index, density, andmolecular weight (n-d-M).2This test method should not beapplied to oils whose compositions are outside the followingranges:1.1.1 In terms of carbon distributionup to 75 % carbonatoms in ring st
4、ructure; percentage in aromatic rings not largerthan 1.5 times the percentage in naphthenic rings.1.1.2 In terms of ring contentup to four rings per mol-ecule with not more than half of them aromatic. A correctionmust be applied for oils containing significant quantities ofsulfur.NOTE 1The compositi
5、on of complex petroleum fractions is oftenexpressed in terms of the proportions of aromatic rings (RA), naphthenerings (RN), and paraffin chains (CP) that would comprise a hypotheticalmean molecule. Alternatively, the composition may be expressed in termsof a carbon distribution, that is, the percen
6、tage of the total number ofcarbon 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 thestandard. The values in parentheses are for information only.1.3 This standard does not
7、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 Documents2.1 ASTM Standards:
8、3D1218 Test Method for Refractive Index and RefractiveDispersion of Hydrocarbon LiquidsD1480 Test Method for Density and Relative Density (Spe-cific Gravity) of Viscous Materials by Bingham Pycnom-eterD1481 Test Method for Density and Relative Density (Spe-cific Gravity) of Viscous Materials by Lipk
9、in BicapillaryPycnometerD1552 Test Method for Sulfur in Petroleum Products(High-Temperature Method)D2502 Test Method for Estimation of Mean Relative Mo-lecular Mass of Petroleum Oils from Viscosity Measure-mentsD2503 Test Method for Relative Molecular Mass (Molecu-lar Weight) of Hydrocarbons by Ther
10、moelectric Measure-ment of Vapor PressureD2622 Test Method for Sulfur in Petroleum Products byWavelength Dispersive X-ray Fluorescence Spectrometry3. Summary of Test Method3.1 The refractive index and density of the oil are deter-mined at 20C. The molecular weight is determined experi-mentally or es
11、timated from measurements of viscosity at 37.8and 98.89C (100 and 210F). These data are then used tocalculate the carbon distribution (% CA,%CN,%CP)orthering analysis (RA, RN) using the appropriate set of equations.4. Significance and Use4.1 The carbon distribution and ring content serve to ex-press
12、 the gross composition of the heavier fractions of petro-leum. These data can be used as an adjunct to the bulkproperties in monitoring the manufacture of lubricating oil basestocks by distillation, solvent refining or hydrogenation, orboth, and in comparing the composition of stocks fromdifferent c
13、rude sources. Furthermore, the data can often becorrelated with critical product performance properties.5. Measurement of Physical Properties5.1 Determine the refractive index of the oil at 20C usingTest Method D1218.5.2 Determine the density at 20C using Test MethodD1480 or Test Method D1481.1This
14、test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0K on Correlative Methods.Current edition approved Oct. 1, 2010. Published November 2010. Originallyapproved in 1973. Last previous edition approved
15、in 2005 as D323895(2005).DOI: 10.1520/D3238-95R10.2Van Nes, K., and van Westen, H. A., Aspects of the Constitution of MineralOils, Elsevier, New York, 1951.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST
16、MStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Determine the average molecular weight using TestMethod D2502 or Test Method D2503.6.
17、Determination of Sulfur Content6.1 Determine the percentage of sulfur in the oil using TestMethods 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
18、5 2.51nD20 1.4750! d420 0.8510! (1)w 5 d420 0.8510! 1.11nD20 1.4750! (2)7.2 Calculate the percentage of aromatic carbon (% CA)from v and the molecular weight (M) using one of thefollowing equations:if v is positive: % CA5 430 v 1 3660/M (3)if v is negative: % CA5 670 v 1 3660/M (4)7.3 Calculate the
19、percentage of carbon in total (aromatic andnaphthenic) ring structures (% CR) from w and the molecularweight.if w is positive: % CR5 820 w 3S 1 10000/M (5)if w is negative: % CR5 1440 w 3S 1 10600/ M (6)where:S = mass % sulfur.7.4 Calculate the percentage of naphthenic carbon (% CN)and the percentag
20、e of paraffinic carbon (% CP) as follows:% CN5 % CR%CA(7)% CP5 100%CR(8)7.5 Calculate the average number of aromatic rings permolecule (RA) from v and the molecular weight:if v is positive: RA5 0.44 1 0.055 Mv (9)if v is negative: RA5 0.44 1 0.080 Mv (10)7.6 Calculate the average total number of rin
21、gs per molecule(RT) from w and the molecular weight:if w is positive: RT5 1.33 1 0.146 M w 0.005 S! (11)if w is negative: RT5 1.33 1 0.180 M w 0.005 S! (12)where:S = mass % sulfur.7.7 Calculate the average number of naphthene rings permolecule (RN) by difference:RN5 RT RA(13)7.8 Report ring numbers
22、to the nearest 0.01 ring and carbondistribution to the nearest 0.1 %.8. Precision and Bias8.1 The precision of this test as obtained by statisticalexamination of interlaboratory test results is as follows:8.1.1 RepeatabilityThe difference between successive testresults obtained by the same operator
23、with the same apparatusunder constant operating conditions on identical test materialwould, in the long run, in the normal and correct operation ofthe test method, exceed the values shown in the following tableonly in 1 case in 20:Range Repeatability% CA2.7 to 34.6 0.6% CN23.7 to 47.2 1.2% CP32.3 to
24、 68.6 1.0RA0.12 to 1.69 0.04RN1.61 to 2.90 0.08RT1.73 to 3.77 0.088.1.2 ReproducibilityThe difference between two singleand independent results, obtained by different operators work-ing in different laboratories on identical test material, would, inthe long run, in the normal and correct operation o
25、f the testmethod, exceed the values shown in the following table only in1 case in 20:Range Reproducibility% CA2.7 to 34.6 1.7% CN23.7 to 47.2 3.6% CP32.3 to 68.6 3.4RA0.12 to 1.69 0.09RN1.61 to 2.90 0.23RT1.73 to 3.77 0.238.2 BiasBias cannot be determined because there are noreference materials suit
26、able for determining the bias of this testmethod.9. Keywords9.1 carbon distribution; density; molecular weight; petro-leum oils; refractive index; ring contentASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this stand
27、ard. 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.This standard is subject to revision at any time by the responsible technical committee and must be review
28、ed 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 International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible
29、 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 below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
30、hohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D3238 95 (2010)2
