ASTM D6423-19

Standard Test Method for Determination of pHe of Denatured Fuel Ethanol and Ethanol Fuel Blends

SIGNIFICANCE AND USE
5.1 The acid strength, as measured by pHe, is a good predictor of the corrosion potential of ethanol fuels. It is preferable to total acidity because total acidity does not measure acid strength; overestimates the contribution of weak acids, such as carbonic acid; and can underestimate the corrosion potential of low concentrations of strong acids, such as sulfuric acid.
SCOPE
1.1 This test method covers a procedure to determine a measure of the acid strength of high ethanol content fuels. These include denatured fuel ethanol and ethanol fuel blends. The test method is applicable to denatured fuel ethanol and ethanol fuel blends containing ethanol at 51 % by volume, or more.  
1.2 Acid strength as measured in this test method is defined as pHe. A pHe value for alcohol solutions is not comparable to pH values of water solutions.  
1.2.1 The value of pHe measured will depend somewhat on the fuel blend, the stirring rate, and the time the electrode is in the fuel.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3.1 Hydrogen ion activity in water is expressed as pH and hydrogen ion activity in ethanol is expressed as pHe.  
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.

General Information

• Status: Historical
• Publication Date: 30-Jun-2019
• ICS: 27.060.10 - Liquid and solid fuel burners
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.A0.02 - Oxygenated Fuels and Components

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6423 − 19
Standard Test Method for
Determination of pHe of Denatured Fuel Ethanol and
1
Ethanol Fuel Blends
This standard is issued under the fixed designation D6423; 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* D4175 Terminology Relating to Petroleum Products, Liquid
Fuels, and Lubricants
1.1 This test method covers a procedure to determine a
D4806 Specification for Denatured Fuel Ethanol for Blend-
measure of the acid strength of high ethanol content fuels.
ing with Gasolines for Use as Automotive Spark-Ignition
These include denatured fuel ethanol and ethanol fuel blends.
Engine Fuel
The test method is applicable to denatured fuel ethanol and
D5798 Specification for Ethanol Fuel Blends for Flexible-
ethanol fuel blends containing ethanol at 51 % by volume, or
Fuel Automotive Spark-Ignition Engines
more.
1.2 Acid strength as measured in this test method is defined
3. Terminology
as pHe.ApHe value for alcohol solutions is not comparable to
3.1 For general terminology, refer to Terminology D4175.
pH values of water solutions.
1.2.1 The value of pHe measured will depend somewhat on
3.2 Definitions:
the fuel blend, the stirring rate, and the time the electrode is in
3.2.1 denaturants, n—materials added to ethanol to make it
the fuel.
unsuitable for beverage use under a formula approved by a
1.3 The values stated in SI units are to be regarded as
regulatory agency to prevent the imposition of beverage
standard. No other units of measurement are included in this
alcohol tax. D4806
standard.
3.2.1.1 Discussion—Denaturants are only those materials
1.3.1 Hydrogen ion activity in water is expressed as pH and
added by the denaturer to comply with the approved formula;
hydrogen ion activity in ethanol is expressed as pHe.
any materials absorbed later are not denaturants.
1.4 This standard does not purport to address all of the
3.2.2 denatured fuel ethanol, n—fuel ethanol made unfit for
safety concerns, if any, associated with its use. It is the
beverage use by the addition of denaturants under formula(s)
responsibility of the user of this standard to establish appro-
approved by the applicable regulatory agency to prevent the
priate safety, health, and environmental practices and deter-
imposition of beverage alcohol tax. D4806
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
3.2.3 ethanol, n—ethyl alcohol, the chemical compound,
dance with internationally recognized principles on standard-
CH CH OH. D4806
3 2
ization established in the Decision on Principles for the
3.2.4 ethanol fuel blend, n—a blend of ethanol and hydro-
Development of International Standards, Guides and Recom-
carbons for use in flexible-fuel automotive spark-ignition
mendations issued by the World Trade Organization Technical
engines of which the ethanol portion is 51 % to 83 % by
Barriers to Trade (TBT) Committee.
volume. D5798
2. Referenced Documents
3.2.5 flexible-fuel vehicle, n—a vehicle designed to operate
2
2.1 ASTM Standards:
on both gasoline or ethanol fuel blends and can operate on any
D1193 Specification for Reagent Water
mixture of both. D5798
1 3.2.5.1 Discussion—In the United States, these vehicles
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of have U.S. EPAemissions certifications using gasoline comply-
Subcommittee D02.A0.02 on Oxygenated Fuels and Components.
ing with U.S. EPA requirements and ethanol fuel blends that
Current edition approved July 1, 2019. Published July 2019. Originally approved
meet the requirements of Specification D5798.
in 1999. Last previous edition approved in 2018 as D6423 – 18. DOI: 10.1520/
D6423-19. 3.2.5.2 Discussion—Flex-fuel vehicle and FFV are com-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
monly used synonyms for flexible-fuel vehicle.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3.2.5.3 Discussion—The fuels may also contain anti-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. oxidants, corrosion inhibitors, metal deactivators, and dyes but
*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

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D6423 − 19
do not contain lead additives. A jurisdiction may set limits on 6.2 Electrode—ORION Ross Sure-Flow comb
...

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: D6423 − 18 D6423 − 19
Standard Test Method for
Determination of pHe of Denatured Fuel Ethanol and
1
Ethanol Fuel Blends
This standard is issued under the fixed designation D6423; 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*
1.1 This test method covers a procedure to determine a measure of the acid strength of high ethanol content fuels. These include
denatured fuel ethanol and ethanol fuel blends. The test method is applicable to denatured fuel ethanol and ethanol fuel blends
containing ethanol at 51 % by volume, or more.
1.2 Acid strength as measured in this test method is defined as pHe. A pHe value for alcohol solutions is not comparable to pH
values of water solutions.
1.2.1 The value of pHe measured will depend somewhat on the fuel blend, the stirring rate, and the time the electrode is in the
fuel.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Hydrogen ion activity in water is expressed as pH and hydrogen ion activity in ethanol is expressed as pHe.
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:
D1193 Specification for Reagent Water
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4806 Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel
D5798 Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines
3. Terminology
3.1 For general terminology, refer to Terminology D4175.
3.2 Definitions:
3.2.1 denaturants, n—materials added to ethanol to make it unsuitable for beverage use under a formula approved by a
regulatory agency to prevent the imposition of beverage alcohol tax. D4806
3.2.1.1 Discussion—
Denaturants are only those materials added by the denaturer to comply with the approved formula; any materials absorbed later
are not denaturants.
3.2.2 denatured fuel ethanol, n—fuel ethanol made unfit for beverage use by the addition of denaturants under formula(s)
approved by the applicable regulatory agency to prevent the imposition of beverage alcohol tax. D4806
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.A0.02 on Oxygenated Fuels and Components.
Current edition approved Dec. 1, 2018July 1, 2019. Published December 2018July 2019. Originally approved in 1999. Last previous edition approved in 20142018 as
D6423 – 14.D6423 – 18. DOI: 10.1520/D6423-18.10.1520/D6423-19.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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 ----------------------
D6423 − 19
3.2.3 ethanol, n—ethyl alcohol, the chemical compound, CH CH OH. D4806
3 2
3.2.4 ethanol fuel blend, n—a blend of ethanol and hydrocarbons for use in flexible-fuel automotive spark-ignition engines of
which the ethanol portion is 51 % to 83 % by volume. D5798
3.2.5 flexible-fuel vehicle, n—a vehicle designed to operate on both gasoline or ethanol fuel blends and can operate on any
mixture of both. D5798
3.2.5.1 Discussion—
In the United States, these vehicles have U.S. EPA emissions certifications using gasoline complying with U.S. EPA requirements
and ethanol fuel blends that meet the requirements of Specifi
...