ASTM D664-01

Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration

SCOPE
1.1 This test method covers procedures for the determination of acidic constituents in petroleum products and lubricants soluble or nearly soluble in mixtures of toluene and propan-2-ol (Note 1). 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.
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 an 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 an 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.
1.3 The values stated in acceptable SI units are to be regarded as the 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Nov-2001
• ICS: 75.080 - Petroleum products in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.06.0A - Chemical Analysis

Relations

• Replaces: ASTM D664-95(2001)e1 - Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
• Effective Date: 10-Nov-2001
• Replaced By: ASTM D664-04 - Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
• Effective Date: 01-Feb-2004
• Referred By: ASTM D4174-23 - Standard Practice for Cleaning, Flushing, and Purification of Petroleum Fluid Hydraulic Systems
• Effective Date: 10-Nov-2001
• Referred By: ASTM D6750-23 - Standard Test Methods for Evaluation of Engine Oils in a High-Speed, Single-Cylinder Diesel Engine—1K Procedure (0.4 % Fuel Sulfur) and 1N Procedure (0.04 % Fuel Sulfur)
• Effective Date: 10-Nov-2001
• Referred By: ASTM D8279-23 - Standard Test Method for Determination of Timing-Chain Wear in a Turbocharged, Direct-Injection, Spark-Ignition, Four-Cylinder Engine
• Effective Date: 10-Nov-2001
• Referred By: ASTM D6618-23 - Standard Test Method for Evaluation of Engine Oils in Diesel Four-Stroke Cycle Supercharged 1M-PC Single Cylinder Oil Test Engine
• Effective Date: 10-Nov-2001
• Referred By: ASTM D5770-23 - Standard Test Method for Semiquantitative Micro Determination of Acid Number of Lubricating Oils During Oxidation Testing
• Effective Date: 10-Nov-2001
• Referred By: ASTM D7666-12(2019) - Standard Specification for Triglyceride Burner Fuel
• Effective Date: 10-Nov-2001
• Referred By: ASTM D1534-95(2017) - Standard Test Method for Approximate Acidity in Electrical Insulating Liquids by Color-Indicator Titration
• Effective Date: 10-Nov-2001
• Referred By: ASTM D5967-21 - Standard Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine
• Effective Date: 10-Nov-2001
• Referred By: ASTM D7752-18 - Standard Practice for Evaluating Compatibility of Mixtures of Hydraulic Fluids
• Effective Date: 10-Nov-2001
• Referred By: ASTM D4636-17 - Standard Test Method for Corrosiveness and Oxidation Stability of Hydraulic Oils, Aircraft Turbine Engine Lubricants, and Other Highly Refined Oils
• Effective Date: 10-Nov-2001
• Referred By: ASTM D6923-23 - Standard Test Method for Evaluation of Engine Oils in a High Speed, Single-Cylinder Diesel Engine—Caterpillar 1R Test Procedure
• Effective Date: 10-Nov-2001
• Referred By: ASTM D5282-05(2020) - Standard Test Methods for Compatibility of Construction Material with Silicone Fluid Used for Electrical Insulation
• Effective Date: 10-Nov-2001
• Referred By: ASTM D8048-21ae1 - Standard Test Method for Evaluation of Diesel Engine Oils in T-13 Diesel Engine
• Effective Date: 10-Nov-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
An American National Standard
Designation:D664–01 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 test method was adopted as a joint ASTM-IP standard in 1964.
This test method has been adopted for use by government agencies to replace Method 5106 of Federal Test Method Standard No. 791b.
ASTM Test Method D 4739 has been developed as an alternative to the base number portion of D 664.
1. Scope 1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers procedures for the determina-
responsibility of the user of this standard to establish appro-
tionofacidicconstituentsinpetroleumproductsandlubricants
priate safety and health practices and determine the applica-
soluble or nearly soluble in mixtures of toluene and propan-
bility of regulatory limitations prior to use.
2-ol (Note 1). It is applicable for the determination of acids
−9
whose dissociation constants in water are larger than 10 ;
2. Referenced Documents
extremely weak acids whose dissociation constants are smaller
−9
2.1 ASTM Standards:
than 10 do not interfere. Salts react if their hydrolysis
−9
D974 Test Method for Acid and Base Number by Color-
constants are larger than 10 .
2
Indicator Titration
3
NOTE 1—In new and used oils, the constituents that may be considered
D1193 Specification for Reagent Water
to have acidic characteristics include organic and inorganic acids, esters,
D3339 Test Method for Acid Number of Petroleum Prod-
phenolic compounds, lactones, resins, salts of heavy metals, salts of
4
ucts by Semi-Micro Color Indicator Titration
ammoniaandotherweakbases,acidsaltsofpolybasicacids,andaddition
agents such as inhibitors and detergents.
3. Terminology
1.2 The test method may be used to indicate relative
3.1 Definitions:
changes that occur in an oil during use under oxidizing
3.1.1 acid number, n—the quantity of base, expressed as
conditions regardless of the color or other properties of the
milligrams of potassium hydroxide per gram of sample, re-
resulting oil. Although the titration is made under definite
quired to titrate a sample to a specified end point.
equilibrium conditions, the test method is not intended to
3.1.1.1 Discussion—Thistestmethodexpressesthequantity
measure an absolute acidic property that can be used to predict
of base as milligrams of potassium hydroxide per gram of
performance of an oil under service conditions. No general
sample, that is required to titrate a sample in the solvent from
relationship between bearing corrosion and acid number is
its initial meter reading in millivolts to a meter reading in
known.
millivolts corresponding to a freshly prepared non-aqueous
NOTE 2—Theacidnumberobtainedbythisstandardmayormaynotbe basic buffer solution or a well-defined inflection point as
numerically the same as that obtained in accordance with Test Methods
specified in the test method.
D974 and D3339D974D3339.
3.1.1.2 Discussion—This test method provides additional
1.3 The values stated in acceptable SI units are to be information. The quantity of base, expressed as milligrams of
potassium hydroxide per gram of sample, required to titrate a
regarded as the standard.
sampleinthesolventfromitsinitialmeterreadinginmillivolts
to a meter reading in millivolts corresponding to a freshly
1
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
2
D02.06 on Analysis of Lubricants. Annual Book of ASTM Standards, Vol 05.01.
3
Current edition approved Nov. 10, 2001. Published December 2001. Originally Annual Book of ASTM Standards, Vol 11.01.
´1 4
published as D664–42T. Last previous edition D664–95 (2001) . Annual Book of ASTM Standards, Vol 05.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
D664–01
prepared nonaqueous acidic buffer solution or a well-defined 6.2.1 Meter,avoltmeterorapotentiometerthatwilloperate
inflectionpointasspecifiedinthetestmethodshallbereported with an accuracy of 60.005 V and a sensitivity of 60.002 V
as the strong acid number. overar
...