ASTM D3238-95(2000)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3238 – 95 (Reapproved 2000) An American National Standard
Standard Test Method for
Calculation of Carbon Distribution and Structural Group
Analysis of Petroleum Oils by the n-d-M Method
This standard is issued under the fixed designation D 3238; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope (Specific Gravity) of Viscous Materials by Bingham Pyc-
nometer
1.1 This test method covers the calculation of the carbon
D 1481 Test Method for Density and Relative Density
distribution and ring content (Note 1) of olefin-free petroleum
(Specific Gravity) of Viscous Materials by Lipkin Bicap-
oils from measurements of refractive index, density and
illary Pycnometer
molecular weight (n-d-M). This test method should not be
D 1552 Test Method for Sulfur in Petroleum Products
applied to oils whose compositions are outside the following
(High-Temperature Method)
ranges:
D 2502 Test Method for Estimation of Molecular Weight
1.1.1 In terms of carbon distribution— up to 75 % carbon
(Relative Molecular Mass) of Petroleum Oils from Viscos-
atoms in ring structure; percentage in aromatic rings not larger
ity Measurements
than 1.5 times the percentage in naphthenic rings.
D 2503 Test Method for Molecular Weight (Relative Mo-
1.1.2 In terms of ring content—up to four rings per mol-
lecular Mass) of Hydrocarbons by Thermoelectric Mea-
ecule with not more than half of them aromatic. A correction
surement of Vapor Pressure
must be applied for oils containing significant quantities of
D 2622 Test Method for Sulfur in Petroleum Products by
sulfur.
Wavelength Dispersive X-Ray Fluorescence Spectrom-
NOTE 1—The composition of complex petroleum fractions is often 4
etry
expressed in terms of the proportions of aromatic rings (R ), naphthene
A
rings (R ) and paraffin chains (C ) that would comprise a hypothetical
N P
3. Summary of Test Method
mean molecule. Alternatively, the composition may be expressed in terms
3.1 The refractive index and density of the oil are deter-
of a carbon distribution, that is, the percentage of the total number of
mined at 20°C. The molecular weight is determined experi-
carbon atoms that are present in aromatic ring structures (% C ),
A
naphthene ring structures (% C ), and paraffin chains (% C ). mentally or estimated from measurements of viscosity at 37.8
N p
and 98.89°C (100 and 210°F). These data are then used to
1.2 The values stated in SI units are to be regarded as the
calculate the carbon distribution (% C ,% C ,% C )orthe
A N P
standard. The values in parentheses are for information only.
ring analysis (R , R ) using the appropriate set of equations.
A N
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 The carbon distribution and ring content serve to ex-
priate safety and health practices and determine the applica-
press the gross composition of the heavier fractions of petro-
bility of regulatory limitations prior to use.
leum. These data can be used as an adjunct to the bulk
2. Referenced Documents properties in monitoring the manufacture of lubricating oil base
stocks by distillation, solvent refining or hydrogenation, or
2.1 ASTM Standards:
both, and in comparing the composition of stocks from
D 1218 Test Method for Refractive Index and Refractive
3 different crude sources. Furthermore, the data can often be
Dispersion of Hydrocarbon Liquids
correlated with critical product performance properties.
D 1480 Test Method for Density and Relative Density
5. Measurement of Physical Properties
5.1 Determine the refractive index of the oil at 20°C using
This test method is under the jurisdiction of ASTM Committee D02 on
Test Method D 1218.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analyses. 5.2 Determine the density at 20°C using Test Method
Current edition approved Aug. 15, 1995. Published October 1995. Originally
D 1480 or Test Method D 1481.
published as D 3238 – 73 T. Last previous edition D 3238 – 90.
Van Nes, K., and van Westen, H. A., Aspects of the Constitution of Mineral
Oils, Elsevier, New York, 1951.
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