ASTM D6423-14

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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-Dec-2014
• 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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 − 14
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* D5798 Specification for Ethanol Fuel Blends for Flexible-
Fuel Automotive Spark-Ignition Engines
1.1 This test method covers a procedure to determine a
measure of the acid strength of high ethanol content fuels.
3. Terminology
These include denatured fuel ethanol and ethanol fuel blends.
The test method is applicable to denatured fuel ethanol and
3.1 For general terminology, refer to Terminology D4175.
ethanol fuel blends containing ethanol at 51 % by volume, or
3.2 Definitions:
more.
3.2.1 denaturants, n—materials added to ethanol to make it
1.2 Acid strength as measured in this test method is defined
unsuitable for beverage use under a formula approved by a
as pHe.ApHe value for alcohol solutions is not comparable to
regulatory agency to prevent the imposition of beverage
pH values of water solutions.
alcohol tax. D4806
1.2.1 The value of pHe measured will depend somewhat on
3.2.1.1 Discussion—Denaturants are only those materials
the fuel blend, the stirring rate, and the time the electrode is in
added by the denaturer to comply with the approved formula;
the fuel.
any materials absorbed later are not denaturants.
1.3 The values stated in SI units are to be regarded as
3.2.2 denatured fuel ethanol, n—fuel ethanol made unfit for
standard. No other units of measurement are included in this
beverage use by the addition of denaturants under formula(s)
standard.
approved by the applicable regulatory agency to prevent the
1.3.1 Hydrogen ion activity in water is expressed as pH and
imposition of beverage alcohol tax. D4806
hydrogen ion activity in ethanol is expressed as pHe.
3.2.3 ethanol, n—ethyl alcohol, the chemical compound,
1.4 This standard does not purport to address all of the
C H OH.
2 5
safety concerns, if any, associated with its use. It is the
3.2.4 ethanol fuel blend, n—a blend of ethanol and hydro-
responsibility of the user of this standard to establish appro-
carbons for use in flexible-fuel automotive spark-ignition
priate safety and health practices and determine the applica-
engines of which the ethanol portion is 51 % to 83 % by
bility of regulatory limitations prior to use.
volume. D5798
2. Referenced Documents
3.2.5 flexible-fuel vehicle, n—a vehicle designed to operate
2
2.1 ASTM Standards: on either unleaded gasoline or ethanol fuel blends or mixtures
D1193 Specification for Reagent Water
of both. D5798
D4175 Terminology Relating to Petroleum, Petroleum
3.2.6 fuel ethanol, n—a grade of undenatured ethanol with
Products, and Lubricants
other components common to its production (including water)
D4806 Specification for Denatured Fuel Ethanol for Blend-
that do not affect the use of the product as a component for
ing with Gasolines for Use as Automotive Spark-Ignition
automotive spark-ignition engine fuels. D4806
Engine Fuel
3.2.7 hydrocarbon, n—a compound composed solely of
hydrogen and carbon. D5798
1
This test method is under the jurisdiction of ASTM Committee D02 on
3.3 Definitions of Terms Specific to This Standard:
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.A0.02 on Oxygenated Fuels and Components.
3.3.1 pHe, n—a measure of the acid strength of ethanol-
Current edition approved Dec. 15, 2014. Published February 2015. Originally
hydrocarbon blends defined by this apparatus and procedure.
approved in 1999. Last previous edition approved in 2008 as D6423 – 08. DOI:
10.1520/D6423-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 4. Summary of Test Method
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4.1 The sample is analyzed at room temperature using a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. specified electrode system and a pH meter with an input
*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 − 14
12
impedance >10 Ω (ohms). Meters designed for use with different results under some or all conditions due to the use of
ion-specific electrodes normally meet this criteria. a different size or type of glass membrane for the pH electrode,
a different type of salt bridge junction, or other small
4.
...

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 − 08 D6423 − 14
Standard Test Method for
Determination of pHe of Ethanol, Denatured Fuel
1
Ethanol,Ethanol and Fuel Ethanol (Ed75-Ed85)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
ethanol, denatured fuel ethanol,ethanol and fuel ethanol (Ed75-Ed85). fuel blends. The test method is applicable to fuels containing
nominally 70 volume % ethanol, or higher, as described in Specifications denatured fuel ethanol and ethanol fuel blends containing
ethanol at 51 % by volume, or more.D4806 and D5798.
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
-5
values of water solutions. For example, a 1.5×10 M (18 ppm) solution of H SO gives a pH of about 5.5 in water solution, but,
2 4
depending on buffering strength, a pHe as low as 1 to 2 in unadditized alcohol fuel.
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 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D4175 Terminology Relating to Petroleum, Petroleum Products, 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—natural gasoline, gasoline components, unleaded gasoline, or toxic or noxious materials added to fuel
ethanol to make it unsuitable for beverage use but not unsuitable for automotive fuel use.under a formula approved by a 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. 15, 2008Dec. 15, 2014. Published February 2009February 2015. Originally approved in 1999. Last previous edition approved in 20042008
as D6423–99(2004).D6423 – 08. DOI: 10.1520/D6423-08.10.1520/D6423-14.
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.
3.2.1.1 Discussion—
*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 − 14
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.denaturants under
formula(s) approved by the applicable regulatory agency to prevent the imposition of beverage alcohol tax. D4806
3.2.3 ethanol, n—ethyl alcohol, the chemical compound, C H OH.
2 5
3.2.4 fuel ethanol (Ed75-Ed85), fuel blend, n—a blend of ethanol and hydrocarbons for use in flexible-fuel automotive
spark-ignition engines of which the ethanol portion is nominally 75 to 85 volume % denatured ethanol.51 % to 83 % by volume.
D5
...