ASTM D2896-07a
(Test Method)Standard Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration
Standard Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration
SIGNIFICANCE AND USE
New and used petroleum products can contain basic constituents that are present as additives. The relative amounts of these materials can be determined by titration with acids. The base number is a measure of the amount of basic substance in the oil, always under the conditions of the test. It is sometimes used as a measure of lubricant degradation in service; however, any condemning limits must be empirically established.
SCOPE
1.1 This test method covers the determination of basic constituents in petroleum products by titration with perchloric acid in glacial acetic acid.
1.2 Procedures A and B use different titration solvent volumes and sample weights. Note 1 - A round robin on a series of new and used oils and additive concentrates has shown that the two procedures give statistically equivalent results.
1.3 Appendix X2 provides the use of an alternative solvent system which eliminates the use of chlorobenzene in this test method. The use of the alternative solvent gives statistically equivalent results; however, the precision is worse. Paragraph provides guidance when comparing results using the two different solvents.
1.4 The constituents that may be considered to have basic characteristics include organic and inorganic bases, amino compounds, salts of weak acids (soaps), basic salts of polyacidic bases, and salts of heavy metals. Note 2 - This test method is applicable to both fresh oils and used oils as described in Sections 16, 17, and 19 and Appendix X1.
1.5 This test method can be used to determine base number >300 mg KOH/g. However, the precision statement in Section has been obtained only on base number 300 mg KOH/g.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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. For specific warning statements, see Section 7, Section 10, and X2.2.
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Designation:D2896–07a
Designation: 276/95
Standard Test Method for
Base Number of Petroleum Products by Potentiometric
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Perchloric Acid Titration
This standard is issued under the fixed designation D2896; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope* responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This test method covers the determination of basic
bility of regulatory limitations prior to use. For specific
constituents in petroleum products by titration with perchloric
warning statements, see Section 7, Section 10, and X2.2.
acid in glacial acetic acid.
1.2 Procedures A and B use different titration solvent
2. Referenced Documents
volumes and sample weights.
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2.1 ASTM Standards:
NOTE 1—A round robin on a series of new and used oils and additive
D1193 Specification for Reagent Water
concentrates has shown that the two procedures give statistically equiva-
lent results.
3. Terminology
1.3 Appendix X2 provides the use of an alternative solvent
3.1 Definitions of Terms Specific to This Standard:
system which eliminates the use of chlorobenzene in this test
3.1.1 base number—the quantity of perchloric acid ex-
method. The use of the alternative solvent gives statistically
pressed in terms of the equivalent number of milligrams of
equivalent results; however, the precision is worse. Paragraph
potassium hydroxide that are required to titrate1gofthe
X2.5.5 provides guidance when comparing results using the
sample dissolved in the specified solvent to a well-defined
two different solvents.
inflection point as specified in this test method.
1.4 The constituents that may be considered to have basic
4. Summary of Test Method
characteristics include organic and inorganic bases, amino
compounds, salts of weak acids (soaps), basic salts of poly-
4.1 The sample is dissolved in an essentially anhydrous
acidic bases, and salts of heavy metals.
mixture of chlorobenzene and glacial acetic acid and titrated
with a solution of perchloric acid in glacial acetic acid using
NOTE 2—This test method is applicable to both fresh oils and used oils
potentiometric titrimeter. A glass indicating electrode and a
as described in Sections 16, 17, and 19 and Appendix X1.
reference electrode are used, the latter being connected with
1.5 This test method can be used to determine base number
the sample solution by means of a salt bridge. The meter
>300 mg KOH/g. However, the precision statement in Section
readings are plotted against the respective volumes of titrating
19 has been obtained only on base number#300 mg KOH/g.
solution, and the end point is taken at the inflection in the
1.6 The values stated in SI units are to be regarded as
resulting curve.
standard. No other units of measurement are included in this
4.2 ProcedureAuses120mLoftitrationsolvent.Procedure
standard.
B uses 60 mL of titration solvent. In addition, the two
1.7 This standard does not purport to address all of the
proceduresusedifferentequationsforthecalculationofappro-
safety concerns, if any, associated with its use. It is the
priate sample weights. Since many portions of the test method
are identical for ProceduresAand B, only the unique sections
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will be described separately for the two versions of the test
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee method.
D02.06 on Analysis of Lubricants.
Current edition approved July 15, 2007. Published August 2007. Originally
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approved in 1970. Last previous edition approved in 2007 as D2896–07. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method has been approved by the sponsoring committees and accepted contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
by the cooperating societies in accordance with established procedures. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D2896-07A. the ASTM website.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D2896–07a
4.3 Occasionally certain used oils give no inflection in the 7. Reagents and Materials
forward titration mode, in which case a back titration modifi-
7.1 Purity of Reagents—Reagent grade chemicals shall b
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