ASTM D4739-05
(Test Method)Standard Test Method for Base Number Determination by Potentiometric Titration
Standard Test Method for Base Number Determination by Potentiometric Titration
SCOPE
1.1 This test method covers a procedure for the determination of basic constituents in petroleum products and lubricants (Note 0). The test method resolves these constituents into groups having weak-base and strong-base ionization properties, provided the dissociation constants of the more strongly basic compounds are at least 1000 times that of the next weaker groups.
1.1.1 This test method covers base numbers up to 70. While it can be extended to higher base numbers, the precision of the test method for base numbers greater than 70 has not been determined. Note 0In new and used oils, the constituents which can be considered to have basic properties are primarily organic and inorganic bases, including amino compounds, although certain salts of heavy metals, salts of weak acids, basic salts of polyacidic compounds, and some additives such as inhibitors or detergents may show basic characteristics.
1.2 This test method can be used to indicate relative changes that occur in an oil during use under oxidizing or other service conditions regardless of the color or other properties of the resulting oil (Note 0). Although the analysis is made under closely specified conditions, the method is not intended to, and does not, result in reported basic properties which can be used under all service conditions to predict performance of an oil; for example, no overall relationship is known between bearing corrosion or the control of corrosive wear in the engine and base number. Note 3
Test Method D 4739 was developed as an alternative for the former base number portion of Test Method D 664. Base numbers obtained by this method may or may not be numerically the same as those obtained by the former base number portion of Test Method D 664.Note 0
A color indicator titration method is also available in the Test Method D 974 and IP 139. The base numbers obtained by the potentiometric method may or may not be numerically the same as those obtained by Test Method D 974 or equivalent color indicator methods such as given in Federal Test Method Std. No. 791b. Potentiometric methods for base number are also available in Test Method D 2896.
1.3 &solely-SI-units;
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation:D4739–05
Standard Test Method for
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Base Number Determination by Potentiometric Titration
This standard is issued under the fixed designation D4739; 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* 1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This test method covers a procedure for the determina-
standard.
tion of basic constituents in petroleum products and lubricants
1.4 This standard does not purport to address all of the
(Note 1). The test method resolves these constituents into
safety concerns, if any, associated with its use. It is the
groups having weak-base and strong-base ionization proper-
responsibility of the user of this standard to establish appro-
ties, provided the dissociation constants of the more strongly
priate safety and health practices and determine the applica-
basiccompoundsareatleast1000timesthatofthenextweaker
bility of regulatory limitations prior to use.
groups.
1.1.1 Thistestmethodcoversbasenumbersupto70.While
2. Referenced Documents
it can be extended to higher base numbers, the precision of the
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2.1 ASTM Standards:
test method for base numbers greater than 70 has not been
D664 TestMethodforAcidNumberofPetroleumProducts
determined.
by Potentiometric Titration
NOTE 1—In new and used oils, the constituents which can be consid-
D974 Test Method for Acid and Base Number by Color-
ered to have basic properties are primarily organic and inorganic bases,
Indicator Titration
including amino compounds, although certain salts of heavy metals, salts
D1193 Specification for Reagent Water
of weak acids, basic salts of polyacidic compounds, and some additives
D2896 Test Method for Base Number of Petroleum Prod-
such as inhibitors or detergents may show basic characteristics.
ucts by Potentiometric Perchloric Acid Titration
1.2 Thistestmethodcanbeusedtoindicaterelativechanges
2.2 IP Standard:
that occur in an oil during use under oxidizing or other service
IP139 Test Method for Acid Number by Color-Indicator
conditions regardless of the color or other properties of the
Titration Method, IP Standards for Petroleum and Its
resulting oil (Note 3). Although the analysis is made under
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Products, Part 1. Methods for Analysis and Testing.
closelyspecifiedconditions,themethodisnotintendedto,and
2.3 U.S. Federal Test Method:
does not, result in reported basic properties which can be used
Federal Test Method Standard No. 791b Lubricants Liquid
under all service conditions to predict performance of an oil;
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Fuels and Related Products; Methods of Testing
for example, no overall relationship is known between bearing
corrosion or the control of corrosive wear in the engine and
3. Terminology
base number.
3.1 Definitions:
NOTE 2—Test Method D4739 was developed as an alternative for the 3.1.1 base numbers, n—the quantity of acid, expressed in
former base number portion of Test Method D664. Base numbers
milligrams of potassium hydroxide per gram of sample that is
obtainedbythismethodmayormaynotbenumericallythesameasthose
required to titrate a sample, dissolved in a specified solvent to
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obtained by the former base number portion of Test Method D664.
a specified end point.
NOTE 3—Acolor indicator titration method is also available in theTest
3.1.1.1 Discussion—In this test method, the sample is
Method D974 and IP139. The base numbers obtained by the potentio-
titrated to a meter reading corresponding to a freshly prepared
metric method may or may not be numerically the same as those obtained
nonaqueous acidic buffer solution.
byTestMethodD974orequivalentcolorindicatormethodssuchasgiven
in Federal Test Method Std. No. 791b. Potentiometric methods for base
number are also available in Test Method D2896.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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This test method is under the jurisdiction of ASTM Committee D02 on Standards volume information, refer to the standard’s Document Summary page on
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee the ASTM website.
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D02.06 on Analysis of Lubricants. Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
Current edition approved Nov. 1, 2005. Published November 2005. Originally U.K.
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approved in 1987. Last previous edition approved in 2002 as D4739–02. Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
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The base number portion was last published in the 1981 version. Section
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