ASTM D7736-19a

Standard Test Method for Determination of Acids and Glycol Esters in Glycols

SIGNIFICANCE AND USE
5.1 The presence of acids or glycol esters in the glycol used to produce engine coolant is undesirable. Under conditions in an engine cooling system, the esters can hydrolyze to form glycol and an acid. The acid will react with the corrosion inhibitors, thereby reducing the useful life of the coolant. This method can determine the amount of acid and glycol ester present in the glycol.
SCOPE
1.1 This test method covers the determination of free acids and glycol esters in glycols by titration.  
1.2 This test method is typically used on glycols used for the manufacture of engine coolant. It cannot be used on formulated engine coolant. The inhibitors will interfere with the determination.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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: 31-Oct-2019
• ICS: 71.100.45 - Refrigerants and antifreezes
• Technical Committee: D15 - Engine Coolants and Related Fluids
• Drafting Committee: D15.04 - Chemical Properties

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D7736 − 19a
Standard Test Method for
1,2
Determination of Acids and Glycol Esters in Glycols
This standard is issued under the fixed designation D7736; 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* E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.1 This test method covers the determination of free acids
E691 Practice for Conducting an Interlaboratory Study to
and glycol esters in glycols by titration.
Determine the Precision of a Test Method
1.2 This test method is typically used on glycols used for the
manufacture of engine coolant. It cannot be used on formulated
3. Terminology
engine coolant. The inhibitors will interfere with the determi-
3.1 Definitions:
nation.
3.1.1 For definitions of terms used in this test method, refer
1.3 The values stated in SI units are to be regarded as
to Terminology D4725.
standard. No other units of measurement are included in this
standard. 4. Summary of Test Method
1.4 This standard does not purport to address all of the
4.1 This test method is used to determine the acid and ester
safety concerns, if any, associated with its use. It is the
content of glycols by titration. The sample is titrated to the
responsibility of the user of this standard to establish appro-
phenolphthalein end point with 0.02 N NaOH to determine the
priate safety, health, and environmental practices and deter-
acidity. Then a known amount of base is added and the sample
mine the applicability of regulatory limitations prior to use.
is heated at 100 °C to hydrolyze the esters. It is then back-
1.5 This international standard was developed in accor-
titrated with 0.02 N sulfuric acid to determine the ester content.
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.1 The presence of acids or glycol esters in the glycol used
mendations issued by the World Trade Organization Technical
to produce engine coolant is undesirable. Under conditions in
Barriers to Trade (TBT) Committee.
an engine cooling system, the esters can hydrolyze to form
glycol and an acid. The acid will react with the corrosion
2. Referenced Documents
inhibitors, thereby reducing the useful life of the coolant. This
3
2.1 ASTM Standards: method can determine the amount of acid and glycol ester
D1176 Practice for Sampling and Preparing Aqueous Solu- present in the glycol.
tions of Engine Coolants or Antirusts for Testing Purposes
6. Interferences
D1193 Specification for Reagent Water
D4725 Terminology for Engine Coolants and Related Fluids
6.1 This test method is based on a color change titration.
D7638 Test Method for Determination of Fatty Acids and
Glycol with a strong color could interfere with the results of
Esters in Glycerin
this method.
6.2 High pH recycled glycols streams will affect the results
of this test method.
1
This test method is under the jurisdiction of ASTM Committee D15 on Engine
Coolants and Related Fluids and is the direct responsibility of Subcommittee
7. Apparatus
D15.04 on Chemical Properties.
Current edition approved Nov. 1, 2019. Published November 2019. Originally
7.1 250 mL Borosilicate Glass Bottles, with screw caps.
approved in 2011. Last previous edition approved in 2019 as D7736–19. DOI:
10.1520/D7736–19A.
8. Reagents and Materials
2
This method has been qualified for use with 1,2 Ethane diol (EG), 1,2 Propane
diol (PG), and 1,3 Propane diol (PDO). ASTM Test Method D7638 has been
8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenol-
approved for use with 1,2,3 Propane triol (glycerin, glycerol).
phthalein in methanol or ethanol and dilute to 100 mL.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 8.3 Sulfuric Acid (H SO ), 0.02 N in water.
2 4
*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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D7736 − 19a
TABLE 1 Recommended Sample Sizes
The weight of the bottles should prevent tipping. Leave caps
Estimated Ester slightly loose to prevent pressure buildup.
Sample Size, g Sample Method
Content, wt %
10.2.2 Determination of the Ester Content—Remove bottles
<0.10 25
...

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: D7736 − 19 D7736 − 19a
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
1,2
Glycols Glycol
This standard is issued under the fixed designation D7736; 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 the determination of free acids and glycol esters in ethylene glycol glycols by titration.
1.2 Laboratory testing has proved that the test method can also be used on propylene glycol and 1,3-propanediol.
1.2 This test method is typically used on glycols used for the manufacture of engine coolant. It cannot be used on formulated
engine coolant. The inhibitors will interfere with the determination.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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
3
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
D1193 Specification for Reagent Water
D4725 Terminology for Engine Coolants and Related Fluids
D7638 Test Method for Determination of Fatty Acids and Esters in Glycerin
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4725.
4. Summary of Test Method
4.1 This test method is used to determine the acid and ester content of ethylene glycol glycols by titration. The sample is titrated
to the phenolphthalein end point with 0.02 N NaOH to determine the acidity. Then a known amount of base is added and the sample
is heated at 100 °C to hydrolyze the esters. It is then back-titrated with 0.02 N sulfuric acid to determine the ester content.
1
This test method is under the jurisdiction of ASTM Committee D15 on Engine Coolants and Related Fluids and is the direct responsibility of Subcommittee D15.04 on
Chemical Properties.
Current edition approved April 1, 2019Nov. 1, 2019. Published April 2019November 2019. Originally approved in 2011. Last previous edition approved in 20182019 as
D7736–12 (2018). –19. DOI: 10.1520/D7736–19.10.1520/D7736–19A.
2
This method has been qualified for use with 1,2 Ethane diol (EG), 1,2 Propane diol (PG), and 1,3 Propane diol (PDO). ASTM Test Method D7638 has been approved
for use with 1,2,3 Propane triol (glycerin, glycerol).
3
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’sstandard’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 ----------------------
D7736 − 19a
5. Significance and Use
5.1 The presence of acids or glycol esters in the ethylene glycol used to produce engine coolant is undesirable. Under conditions
in an engine cooling system, the esters can hydrolyze to form glycol and an acid. The acid will react with the corrosion inhibitors,
thereby reducing the useful life of the coolant. This method can determine the amount of acid and glycol ester present in the
ethylene glycol.
6. Interferences
6.1 This test method is based on a color change titration. Glycol with a strong color could interfere with the results of this
method.
6.2 High pH recycled glycols streams will affect the results of this test method.
7. Apparatus
7.1 250 mL Borosilicate Glass Bott
...