ASTM D664-18
(Test Method)Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
SIGNIFICANCE AND USE
5.1 New and used petroleum products, biodiesel, and blends of biodiesel may contain acidic constituents that are present as additives or as degradation products formed during service, such as oxidation products. The relative amount of these materials can be determined by titrating with bases. The acid number is a measure of this amount of acidic substance in the oil, always under the conditions of the test. The acid number is used as a guide in the quality control of lubricating oil formulations. It is also sometimes used as a measure of lubricant degradation in service. Any condemning limits must be empirically established.
5.2 Since a variety of oxidation products contribute to the acid number and the organic acids vary widely in corrosion properties, the test method cannot be used to predict corrosiveness of oil or biodiesel and blends under service conditions. No general correlation is known between acid number and the corrosive tendency of biodiesel and blends or oils toward metals.
SCOPE
1.1 This test method covers procedures for the determination of acidic constituents in petroleum products, lubricants, biodiesel, and blends of biodiesel.
1.1.1 Test Method A—For petroleum products and lubricants soluble or nearly soluble in mixtures of toluene and propan-2-ol. It is applicable for the determination of acids whose dissociation constants in water are larger than 10–9; extremely weak acids whose dissociation constants are smaller than 10–9 do not interfere. Salts react if their hydrolysis constants are larger than 10–9. The range of acid numbers included in the precision statement is 0.1 mg/g KOH to 150 mg/g KOH.
1.1.2 Test Method B—Developed specifically for biodiesel and biodiesel blends with low acidity and slightly different solubility. This test method requires the use of an automatic titrator with automatic endpoint-seeking capability.
Note 1: In new and used oils, the constituents that may be considered to have acidic characteristics include organic and inorganic acids, esters, phenolic compounds, lactones, resins, salts of heavy metals, salts of ammonia and other weak bases, acid salts of polybasic acids, and addition agents such as inhibitors and detergents.
1.2 The test method may be used to indicate relative changes that occur in oil during use under oxidizing conditions regardless of the color or other properties of the resulting oil. Although the titration is made under definite equilibrium conditions, the test method is not intended to measure an absolute acidic property that can be used to predict performance of oil under service conditions. No general relationship between bearing corrosion and acid number is known.
Note 2: The acid number obtained by this standard may or may not be numerically the same as that obtained in accordance with Test Methods D974 and D3339. There has not been any attempt to correlate this method with other non-titration methods.
Note 3: A few laboratories have made the observation that there is a difference in Test Method D664 results when aqueous versus nonaqueous buffers are used.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D664 − 18 British Standard 4457
Designation 177/96
Standard Test Method for
Acid Number of Petroleum Products by Potentiometric
1
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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
D974andD3339.Therehasnotbeenanyattempttocorrelatethismethod
1. Scope*
with other non-titration methods.
1.1 This test method covers procedures for the determina-
NOTE 3—A few laboratories have made the observation that there is a
tion of acidic constituents in petroleum products, lubricants, difference in Test Method D664 results when aqueous versus nonaqueous
buffers are used.
biodiesel, and blends of biodiesel.
1.1.1 Test Method A—Forpetroleumproductsandlubricants
1.3 The values stated in SI units are to be regarded as
soluble or nearly soluble in mixtures of toluene and propan-2-
standard. No other units of measurement are included in this
ol. It is applicable for the determination of acids whose
standard.
–9
dissociation constants in water are larger than 10 ; extremely
1.4 This standard does not purport to address all of the
–9
weak acids whose dissociation constants are smaller than 10
safety concerns, if any, associated with its use. It is the
do not interfere. Salts react if their hydrolysis constants are
responsibility of the user of this standard to establish appro-
–9
larger than 10 . The range of acid numbers included in the
priate safety, health, and environmental practices and deter-
precision statement is 0.1mg⁄g KOH to 150mg⁄g KOH.
mine the applicability of regulatory limitations prior to use.
1.1.2 Test Method B—Developed specifically for biodiesel
1.5 This international standard was developed in accor-
and biodiesel blends with low acidity and slightly different
dance with internationally recognized principles on standard-
solubility. This test method requires the use of an automatic
ization established in the Decision on Principles for the
titrator with automatic endpoint-seeking capability.
Development of International Standards, Guides and Recom-
NOTE 1—In new and used oils, the constituents that may be considered
mendations issued by the World Trade Organization Technical
to have acidic characteristics include organic and inorganic acids, esters,
Barriers to Trade (TBT) Committee.
phenolic compounds, lactones, resins, salts of heavy metals, salts of
ammoniaandotherweakbases,acidsaltsofpolybasicacids,andaddition
2. Referenced Documents
agents such as inhibitors and detergents.
2
2.1 ASTM Standards:
1.2 The test method may be used to indicate relative
D974Test Method for Acid and Base Number by Color-
changesthatoccurinoilduringuseunderoxidizingconditions
Indicator Titration
regardless of the color or other properties of the resulting oil.
D1193Specification for Reagent Water
Although the titration is made under definite equilibrium
D3339TestMethodforAcidNumberofPetroleumProducts
conditions, the test method is not intended to measure an
by Semi-Micro Color Indicator Titration
absolute acidic property that can be used to predict perfor-
D4057Practice for Manual Sampling of Petroleum and
mance of oil under service conditions. No general relationship
Petroleum Products
between bearing corrosion and acid number is known.
D4177Practice for Automatic Sampling of Petroleum and
NOTE2—Theacidnumberobtainedbythisstandardmayormaynotbe
numerically the same as that obtained in accordance with Test Methods
Petroleum Products
E177Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1
This test method is under the jurisdiction of ASTM Committee D02 on
3. Terminology
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.
3.1 Definitions:
Current edition approved Nov. 1, 2018. Published November 2018. Originally
approved in 1942. Last previous edition approved in 2017 as D664 – 17a. DOI:
2
10.1520/D0664-18. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method was adopted as a jointASTM-IPstandard in 1964.ASTM Test 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
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D664 − 17a D664 − 18 British Standard 4457
Designation 177/96
Standard Test Method for
Acid Number of Petroleum Products by Potentiometric
1
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. A number 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 U.S. Department of Defense.
1. Scope*
1.1 This test method covers procedures for the determination of acidic constituents in petroleum products, lubricants, biodiesel,
and blends of biodiesel.
1.1.1 Test Method A—For petroleum products and lubricants soluble or nearly soluble in mixtures of toluene and propan-2-ol.
–9
It is applicable for the determination of acids whose dissociation constants in water are larger than 10 ; extremely weak acids
–9 –9
whose dissociation constants are smaller than 10 do not interfere. Salts react if their hydrolysis constants are larger than 10 .
The range of acid numbers included in the precision statement is 0.1 mg ⁄g KOH to 150 mg ⁄g KOH.
1.1.2 Test Method B—Developed specifically for biodiesel and biodiesel blends with low acidity and slightly different solubility.
This test method requires the use of an automatic titrator with automatic endpoint-seeking capability.
NOTE 1—In new and used oils, the constituents that may be considered to have acidic characteristics include organic and inorganic acids, esters,
phenolic compounds, lactones, resins, salts of heavy metals, salts of ammonia and other weak bases, acid salts of polybasic acids, and addition agents
such as inhibitors and detergents.
1.2 The test method may be used to indicate relative changes that occur in oil during use under oxidizing conditions regardless
of the color or other properties of the resulting oil. Although the titration is made under definite equilibrium conditions, the test
method is not intended to measure an absolute acidic property that can be used to predict performance of oil under service
conditions. No general relationship between bearing corrosion and acid number is known.
NOTE 2—The acid number obtained by this standard may or may not be numerically the same as that obtained in accordance with Test Methods D974
and D3339. There has not been any attempt to correlate this method with other non-titration methods.
NOTE 3—A few laboratories have made the observation that there is a difference in Test Method D664 results when aqueous versus nonaqueous buffers
are used.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
D974 Test Method for Acid and Base Number by Color-Indicator Titration
D1193 Specification for Reagent Water
D3339 Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
1
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.06 on Analysis of Liquid Fuels and Lubricants.
Current edition approved Dec. 15, 2017Nov. 1, 2018. Published March 2018November 2018. Originally approved in 1942. Last previous edition approved in 2017 as D664
– 17.17a. DOI: 10.1520/D0664-17A.10.1520/D0664-18.
This test method was adopted as a joint ASTM-IP standard in 1964. ASTM Test Method D4739 has been developed as an alternative to the base number portion of D664.
2
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Cha
...
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