ASTM D8045-17
(Test Method)Standard Test Method for Acid Number of Crude Oils and Petroleum Products by Catalytic Thermometric Titration
Standard Test Method for Acid Number of Crude Oils and Petroleum Products by Catalytic Thermometric Titration
SIGNIFICANCE AND USE
5.1 Crude oils and oil sands bitumen contain naturally occurring acidic species. Acidity of crude oil has been implicated in corrosion of distribution and process systems. 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 under the conditions of the test.
5.2 Acid number of crude and distilled petroleum fractions has been measured by Test Method D664. Test Method D664 was developed for the analysis of lubricants and biodiesel. The titration solvent used in Test Method D664 does not properly address dissolving difficult samples such as crude oil, bitumen, and high wax samples addressed in this test method. Refer to Appendix X1.
5.3 Test Method D974 is also not applicable to measuring acidity of crudes and highly colored samples because the indicator is not visible or it is difficult to discern a color change to detect the end point of the titration.
SCOPE
1.1 This test method covers the determination of acidic components in crude oil and petroleum products including waxes, bitumen, base stocks, and asphalts that are soluble in mixtures of xylenes 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. The values obtained by this test method may not be numerically equivalent to other acid value measurements. The range of KOH acid numbers included in the precision statement is 0.1 mg/g to 16 mg/g.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. Some specific hazards statements are given in Section 7 on Safety Precautions.
1.4 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.
General Information
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Designation: D8045 − 17
Standard Test Method for
Acid Number of Crude Oils and Petroleum Products by
1
Catalytic Thermometric Titration
This standard is issued under the fixed designation D8045; 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.
1. Scope* by Potentiometric Titration
D974 Test Method for Acid and Base Number by Color-
1.1 This test method covers the determination of acidic
Indicator Titration
components in crude oil and petroleum products including
D1193 Specification for Reagent Water
waxes, bitumen, base stocks, and asphalts that are soluble in
D4057 Practice for Manual Sampling of Petroleum and
mixtures of xylenes and propan-2-ol. It is applicable for the
Petroleum Products
determination of acids whose dissociation constants in water
–9 D4175 Terminology Relating to Petroleum Products, Liquid
are larger than 10 ; extremely weak acids whose dissociation
–9 Fuels, and Lubricants
constants are smaller than 10 do not interfere. The values
D4177 Practice for Automatic Sampling of Petroleum and
obtainedbythistestmethodmaynotbenumericallyequivalent
Petroleum Products
to other acid value measurements. The range of KOH acid
D5854 Practice for Mixing and Handling of Liquid Samples
numbers included in the precision statement is 0.1 mg⁄g to
of Petroleum and Petroleum Products
16 mg⁄g.
D6299 Practice for Applying Statistical Quality Assurance
1.2 The values stated in SI units are to be regarded as
and Control Charting Techniques to Evaluate Analytical
standard. No other units of measurement are included in this
Measurement System Performance
standard.
3. Terminology
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.1 For general terminology, refer to Terminology D4175.
responsibility of the user of this standard to establish appro-
3.2 Definitions:
priate safety and health practices and determine the applica-
3.2.1 acid number, n—the quantity of a specified base,
bility of regulatory limitations prior to use. Some specific
expressed in milligrams of potassium hydroxide per gram of
hazards statements are given in Section 7 on Safety Precau-
sample, required to titrate a sample in a specified solvent to a
tions.
specified endpoint using a specified detection system.
1.4 This international standard was developed in accor-
3.2.2 catalytic thermometric titration, n—a method to de-
dance with internationally recognized principles on standard-
termine the end point of a chemical reaction through the use a
ization established in the Decision on Principles for the
temperaturemeasuringdeviceandtheadditionofachemicalto
Development of International Standards, Guides and Recom-
enhance the detection of the endpoint.
mendations issued by the World Trade Organization Technical
3.2.3 crude oil, n—a naturally occurring hydrocarbon
Barriers to Trade (TBT) Committee.
mixture, generally in a liquid state, which may also include
2. Referenced Documents
compounds of sulfur, nitrogen, oxygen, metals, and other
2
elements.
2.1 ASTM Standards:
D664 Test Method for Acid Number of Petroleum Products
4. Summary of Test Method
4.1 The sample and a fixed mass of paraformaldehyde are
1
This test method is under the jurisdiction of ASTM Committee D02 on
dissolvedinamixtureofxylenesandpropan-2-ol.Themixture
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
is then titrated with potassium hydroxide using a constant rate
Subcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.
of titrant addition. A plot of the temperature of the reaction
Current edition approved July 1, 2017. Published July 2017. Originally approved
ɛ1
mixture versus the volume of titrant is generated. An exother-
in 2016. Last previous edition approved in 2016 as D8045 – 16 . DOI: 10.1520/
D8045-17.
mic reaction between the titrant and sample occurs simultane-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ously with the endothermic depolymerization of paraformalde-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
hyde.After all of the acidic material in the sample has reacted,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the slope of the plot changes due to the absence of the
*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
1
---------------------- Page: 1 ----------------------
D8045 − 17
competitive exothermic acid-base
...
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.
´1
Designation: D8045 − 16 D8045 − 17
Standard Test Method for
Acid Number of Crude Oils and Petroleum Products by
1
Catalytic Thermometric Titration
This standard is issued under the fixed designation D8045; 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.
1
ε NOTE—Footnote 4 was added editorially in December 2016.
1. Scope Scope*
1.1 This test method covers the determination of acidic components in crude oil and petroleum products including waxes,
bitumen, base stocks, and asphalts that are soluble in mixtures of xylenes and propan-2-ol. It is applicable for the determination
–9
of acids whose dissociation constants in water are larger than 10 ; extremely weak acids whose dissociation constants are smaller
–9
than 10 do not interfere. The values obtained by this test method may not be numerically equivalent to other acid value
measurements. The range of KOH acid numbers included in the precision statement is 0.1 mg ⁄g to 16 mg ⁄g.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. Some specific hazards statements are given in Section 7 on Safety Precautions.
1.4 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:
D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration
D974 Test Method for Acid and Base Number by Color-Indicator Titration
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
3. Terminology
3.1 For general terminology, refer to Terminology D4175.
3.2 Definitions:
3.2.1 acid number, n—the quantity of a specified base, expressed in milligrams of potassium hydroxide per gram of sample,
required to titrate a sample in a specified solvent to a specified endpoint using a specified detection system.
3.2.2 catalytic thermometric titration, n—a method to determine the end point of a chemical reaction through the use a
temperature measuring device and the addition of a chemical to enhance the detection of the endpoint.
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.
ɛ1
Current edition approved July 1, 2016July 1, 2017. Published August 2016July 2017. Originally approved in 2016. Last previous edition approved in 2016 as D8045 – 16 .
DOI: 10.1520/D8045-16E01.10.1520/D8045-17.
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 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
1
---------------------- Page: 1 ----------------------
D8045 − 17
3.2.3 crude oil, n—a naturally occurring hydrocarbon mixture, generally in a liquid state, which may also include compounds
of sulfur, nitrogen, oxygen, metals, and other elements.
4. Summary of Test Method
4.1 The sample and a fixed mass of paraformaldehyde are dissolved in a mixture of xylenes and propan-2-ol. The mixture is
then titrated with potassium hydroxide using a
...
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