ASTM D6423-20a

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

SIGNIFICANCE AND USE
5.1 The hydrogen ion activity, 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 activity of the hydrogen ions; 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 hydrogen ion activity 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 Hydrogen ion activity 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: Published
• Publication Date: 30-Jun-2020
• 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

Relations

• Refers: ASTM D4814-20 - Standard Specification for Automotive Spark-Ignition Engine Fuel
• Effective Date: 01-Feb-2020

Standards Content (Sample)

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.
Designation: D6423 − 20a
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 hydrogen ion activity of high ethanol content
ing with Gasolines for Use as Automotive Spark-Ignition
fuels. These include denatured fuel ethanol and ethanol fuel
Engine Fuel
blends. The test method is applicable to denatured fuel ethanol
D4814 Specification for Automotive Spark-Ignition Engine
and ethanol fuel blends containing ethanol at 51 % by volume,
Fuel
or more.
D5798 Specification for Ethanol Fuel Blends for Flexible-
1.2 Hydrogen ion activity as measured in this test method is
Fuel Automotive Spark-Ignition Engines
defined as pHe. A pHe value for alcohol solutions is not
comparable to pH values of water solutions.
3. Terminology
1.2.1 The value of pHe measured will depend somewhat on
3.1 For general terminology, refer to Terminology D4175.
the fuel blend, the stirring rate, and the time the electrode is in
the fuel.
3.2 Definitions:
3.2.1 conventional-fuel vehicle, n—a vehicle designed to
1.3 The values stated in SI units are to be regarded as
operate on spark-ignition engine fuel that complies with
standard. No other units of measurement are included in this
Specification D4814. D5798
standard.
1.3.1 Hydrogen ion activity in water is expressed as pH and
3.2.2 denaturants, n—materials added to ethanol to make it
hydrogen ion activity in ethanol is expressed as pHe.
unsuitable for beverage use under a formula approved by a
1.4 This standard does not purport to address all of the regulatory agency to prevent the imposition of beverage
safety concerns, if any, associated with its use. It is the alcohol tax. D4806
responsibility of the user of this standard to establish appro-
3.2.2.1 Discussion—Denaturants are only those materials
priate safety, health, and environmental practices and deter-
added by the denaturer to comply with the approved formula;
mine the applicability of regulatory limitations prior to use.
any materials absorbed later are not denaturants.
1.5 This international standard was developed in accor-
3.2.3 denatured fuel ethanol, n—fuel ethanol made unfit for
dance with internationally recognized principles on standard-
beverage use by the addition of denaturants under formula(s)
ization established in the Decision on Principles for the
approved by the applicable regulatory agency to prevent the
Development of International Standards, Guides and Recom-
imposition of beverage alcohol tax. D4806
mendations issued by the World Trade Organization Technical
3.2.4 ethanol, n—ethyl alcohol, the chemical compound,
Barriers to Trade (TBT) Committee.
CH CH OH. D4806
3 2
2. Referenced Documents
3.2.5 ethanol fuel blend, n—an automotive spark-ignition
2
2.1 ASTM Standards:
engine fuel composed of hydrocarbon and ethanol blendstocks
D1193 Specification for Reagent Water
for flexible-fuel vehicles with ethanol concentrations greater
than those used for conventional-fuel vehicles. D5798
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
3.2.5.1 Discussion—Ethanol fuel blends are often referred
Subcommittee D02.A0.02 on Oxygenated Fuels and Components.
to as Ethanol Flex Fuel or EXX, where XX represents the
Current edition approved July 1, 2020. Published July 2020. Originally approved
nominal percentage by volume of denatured fuel ethanol in the
in 1999. Last previous edition approved in 2020 as D6423 – 20. DOI: 10.1520/
D6423-20A.
finished fuel. D5798
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.6 flexible-fuel vehicle, n—a vehicle designed to operate
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
on both gasoline or ethanol fuel blends and can operate on any
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. mixture of both. D5798
*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. Unite
...

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 − 20 D6423 − 20a
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 hydrogen ion activity 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 Hydrogen ion activity 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
D4814 Specification for 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 conventional-fuel vehicle, n—a vehicle designed to operate on spark-ignition engine fuel that complies with Specification
D4814. D5798
3.2.2 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
3.2.2.1 Discussion—
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 May 1, 2020July 1, 2020. Published May 2020July 2020. Originally approved in 1999. Last previous edition approved in 20192020 as
D6423 – 19.D6423 – 20. DOI: 10.1520/D6423-20.10.1520/D6423-20A.
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

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D6423 − 20a
Denaturants are only those materials added by the denaturer to comply with the approved formula; any materials absorbed later
are not denaturants.
3.2.3 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
3.2.4 ethanol, n—ethyl alcohol, the chemical compound, CH CH OH. D4806
3 2
3.2.5 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.an automotive spark-ignition engine fuel composed of hydrocarbon and
ethanol blendstocks for flexible-fuel vehicles with ethanol concentrations gre
...