1、Designation: D3238 95 (Reapproved 2015)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 moleculewith not more than half of them aromatic.Acorrection must beapplied for oils containing significant quantities of sulfur.NOTE 1The composition
5、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 percentag
6、e 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 pur
7、port 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:3D1
8、218 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 Lipkin
9、BicapillaryPycnometerD1552 Test Method for Sulfur in Petroleum Products byHigh Temperature Combustion and IR DetectionD2502 Test Method for Estimation of Mean Relative Mo-lecular Mass of Petroleum Oils from Viscosity Measure-mentsD2503 Test Method for Relative Molecular Mass (MolecularWeight) of Hyd
10、rocarbons by Thermoelectric 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 20 C. The molecular weight is determined exp
11、eri-mentally or estimated from measurements of viscosity at37.8 C and 98.89 C (100 F and 210 F). These data are thenused to calculate the carbon distribution (% CA,%CN,%CP)or the ring analysis (RA, RN) using the appropriate set ofequations.4. Significance and Use4.1 The carbon distribution and ring
12、content serve to ex-press 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
13、of stocks fromdifferent crude 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 20 C usingTest Method D1218.5.2 Determine the density at 20 C using Test MethodD1480
14、or Test Method D1481.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0K on Correlative Methods.Current edition approved Oct. 1, 2015. Published December 2015. Originallyapprove
15、d in 1973. Last previous edition approved in 2010 as D3238 95 (2010).DOI: 10.1520/D3238-95R15.2Van 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 Servic
16、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.3 Determine the average molecular weight usin
17、g TestMethod D2502 or Test Method D2503.6. 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 refractiv
18、e index (n) using the followingequations:v 5 2.51nD202 1.4750! 2d4202 0.8510!(1)w 5 d4202 0.8510! 2 1.11nD202 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 v13660/M (3)if v is negati
19、ve:% CA5 670 v13660/M (4)7.3 Calculate the percentage of carbon in total (aromatic andnaphthenic) ring structures (% CR) from w and the molecularweight.if w is positive:% CR5 820 w 2 3 S110000/M (5)if w is negative:% CR5 1440w 2 3 S110600/M (6)where:S = mass % sulfur.7.4 Calculate the percentage of
20、naphthenic carbon (% CN)and the percentage of paraffinic carbon (% CP) as follows:% CN5 % CR2 % CA(7)% CP5 100 2 % CR(8)7.5 Calculate the average number of aromatic rings permolecule (RA) from v and the molecular weight:if v is positive:RA5 0.4410.055 Mv (9)if v is negative:RA5 0.4410.080 Mv (10)7.6
21、 Calculate the average total number of rings per molecule(RT) from w and the molecular weight:if w is positive:RT5 1.3310.146 M w 2 0.005 S! (11)if w is negative:RT5 1.3310.180 M w 2 0.005 S! (12)where:S = mass % sulfur.7.7 Calculate the average number of naphthene rings permolecule (RN) by differen
22、ce:RN5 RT2 RA(13)7.8 Report ring numbers 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 t
23、estresults obtained by the same operator 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 t
24、o 34.6 0.6% CN23.7 to 47.2 1.2% CP32.3 to 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 r
25、un, in the normal and correct operation of 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 bec
26、ause there are noreference materials suitable 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 conne
27、ction 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.This standard is subject to revision at any time by the responsi
28、ble 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 International Headquarters. Your comments will receive careful co
29、nsideration 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 below.This standard is copyrighted by ASTM International, 100
30、 Barr Harbor Drive, PO Box C700, West Conshohocken, 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 Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 95 (2015)2
