ASTM D664-06ae1

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An American National Standard
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Designation:D664–06a British Standard 4457
Designation 177/96
Standard Test Method for
Acid Number of Petroleum Products by Potentiometric
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Titration
This standard is issued under the fixed designation D664; 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.
This standard has been approved for use by agencies of the Department of Defense.
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e NOTE—Editorial corrections to 8.2, Eq 2, and Fig. 1 were made in April 2007.
1. Scope* 1.3 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
1.1 This test method covers procedures for the determina-
only.
tionofacidicconstituentsinpetroleumproductsandlubricants
1.4 This standard does not purport to address all of the
soluble or nearly soluble in mixtures of toluene and propan-2-
safety concerns, if any, associated with its use. It is the
ol. It is applicable for the determination of acids whose
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responsibility of the user of this standard to establish appro-
dissociation constants in water are larger than 10 ; extremely
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priate safety and health practices and determine the applica-
weak acids whose dissociation constants are smaller than 10
bility of regulatory limitations prior to use.
do not interfere. Salts react if their hydrolysis constants are
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larger than 10 . The range of acid numbers included in the
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2. Referenced Documents
precision statement is 0.1 mg/g KOH to 150 mg/g KOH.
2.1 ASTM Standards:
NOTE 1—In new and used oils, the constituents that may be considered
D974 Test Method for Acid and Base Number by Color-
to have acidic characteristics include organic and inorganic acids, esters,
Indicator Titration
phenolic compounds, lactones, resins, salts of heavy metals, salts of
D1193 Specification for Reagent Water
ammoniaandotherweakbases,acidsaltsofpolybasicacids,andaddition
D3339 Test Method for Acid Number of Petroleum Prod-
agents such as inhibitors and detergents.
ucts by Semi-Micro Color Indicator Titration
1.2 The test method may be used to indicate relative
D4057 Practice for Manual Sampling of Petroleum and
changesthatoccurinoilduringuseunderoxidizingconditions
Petroleum Products
regardless of the color or other properties of the resulting oil.
D4177 Practice for Automatic Sampling of Petroleum and
Although the titration is made under definite equilibrium
Petroleum Products
conditions, the test method is not intended to measure an
absolute acidic property that can be used to predict perfor-
3. Terminology
mance of oil under service conditions. No general relationship
3.1 Definitions:
between bearing corrosion and acid number is known.
3.1.1 acid number, n—the quantity of base, expressed as
NOTE 2—Theacidnumberobtainedbythisstandardmayormaynotbe milligrams of potassium hydroxide per gram of sample, re-
numerically the same as that obtained in accordance with Test Methods
quired to titrate a sample in a specified solvent to a specified
D974 and D3339. There has not been any attempt to correlate this
end point.
method with other non-titration methods.
3.1.1.1 Discussion—Thistestmethodexpressesthequantity
of base as milligrams of potassium hydroxide per gram of
sample, that is required to titrate a sample in a mixture of
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This test method is under the jurisdiction of ASTM Committee D02 on
toluene and propan-2-ol to which a small amount of water has
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee
D02.06 on Analysis of Lubricants.
Current edition approved Nov. 1, 2006. Published November 2006. Originally
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approved in 1942. Last previous edition approved in 2006 as D664–06. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method was adopted as a jointASTM-IPstandard in 1964.ASTMTest contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Method D4739 has been developed as an alternative to the base number portion of Standards volume information, refer to the standard’s Document Summary page on
D664. 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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D664–06a
been added from its initial meter reading in millivolts to a so that no permanent change in the meter readings over the
meter reading in millivolts corresponding to an aqueous basic entire operating range is produced by touching, with a
buffersolutionorawell-definedinflectionpointasspecifiedin grounded lead, any pa
...