ASTM D2502-92(1996)

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D2502–92(Reapproved 1996) An American National Standard
Standard Test Method for
Estimation of Molecular Weight (Relative Molecular Mass) of
Petroleum Oils From Viscosity Measurements
This standard is issued under the fixed designation D2502; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This test method covers the estimation of the mean 4.1 This test method provides a means of calculating the
molecular weight (relative molecular mass) of petroleum oils meanmolecularweight(relativemolecularmass)ofpetroleum
from kinematic viscosity measurements at 100 and 210°F oils from another physical measurement.
(37.78 and 98.89°C). It is applicable to samples with molecu- 4.2 Molecular weight (relative molecular mass) is a funda-
larweightsintherangefrom250to700andisintendedforuse mental physical constant that can be used in conjunction with
with average petroleum fractions. It should not be applied otherphysicalpropertiestocharacterizehydrocarbonmixtures.
indiscriminately to oils that represent extremes of composition
5. Procedure
or possess an exceptionally narrow molecular weight (relative
molecular mass) range. 5.1 Determine the kinematic viscosity of the oil at 100 and
210°F(37.78and98.89°C)asdescribedinTestMethodD445.
1.2 Values stated in inch-pound units are to be regarded as
the standard. The values given in parentheses are provided for 5.2 Look in Table 1 for 100°F (37.78°C) viscosity and read
the value of H that corresponds to the measured viscosity.
information purposes only.
1.3 This standard does not purport to address all of the Linear interpolation between adjacent columns may be re-
quired.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 5.3 Read the viscosity - molecular weight chart for H and
210°F (98.89°C) viscosity.Asimplified version of this chart is
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. shown in Fig. 1 for illustration purposes only (Note 1).
Interpolate where necessary between adjacent lines of 210°F
2. Referenced Documents
viscosity.Afterlocatingthepointcorrespondingtothevalueof
2.1 ASTM Standards: H(ordinate)andthe210°Fviscosity(superimposedlines),read
D445 Test Method for Kinematic Viscosity of Transparent the molecular weight along the abscissa.
and Opaque Liquids (and the Calculation of Dynamic
Example:
Measured viscosity, cSt:
Viscosity)
100°F (37.78°C)5179
2.2 ASTM Adjuncts:
210°F (98.89°C)59.72
Molecular Weight of Petroleum Oils from Viscosity Mea-
surements (D2502)
Look in Table 1 for 179 and read the corresponding value H
5461.
3. Summary of Test Method
Using H 5461 and 210°F viscosity59.72 in conjunction
3.1 The kinematic viscosity of the oil is determined at 100
with chart gives molecular weight (relative molecular
and 210°F (37.78 and 98.89°C).Afunction “ H” of the 100°F
mass)5360 (see Fig. 1).
viscosity is established by reference to a tabulation of H
NOTE 1—A22by28-in.(559by711-mm)chartavailableasanadjunct
function versus 100°F viscosity. The H value and the 210°F
to this test method was used in cooperative testing of the method. If other
viscosity are then used to estimate the molecular weight from
charts are used, the precision statements given in the Precision Section
a correlation chart.
will not apply.
5.4 Report the molecular weight to the nearest whole
number.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analysis. 6. Precision and Bias
Current edition approved Aug. 15, 1992. Published October 1992. Originally
6.1 The precision of this test method as obtained by statis-
published as D2502–66T. Last previous edition D2502–82.
tical examination of interlaboratory test results is as follows:
Hirschler,A. E., Journal of the Institute of Petroleum, JIPEA, Vol 32, 1946, p.
133.
6.1.1 Repeatability—Thedifferencebetweensuccessivetest
Annual Book of ASTM Standards, Vol 05.01.
results obtained by the same operator with the same apparatus
Available from ASTM Headquarters. Order ADJD2502
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D2502
the test method, exceed the value 3g/mol only in one case in
twenty.
6.1.2 Reproducibility—The difference between two single
and independent results, obtained by different operators, work-
ing in different laboratories on identical test material, would in
the long run, in the normal and correct operation of the test
method, exceed the value 25g/mol only in
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