ASTM D7736-19
(Test Method)Standard Test Method for Determination of Acids and Glycol Esters in Ethylene Glycol
Standard Test Method for Determination of Acids and Glycol Esters in Ethylene Glycol
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.
SCOPE
1.1 This test method covers the determination of free acids and glycol esters in ethylene glycol by titration.
1.2 Laboratory testing has proved that the test method can also be used on propylene glycol and 1,3-propanediol.
1.3 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.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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.
1.6 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.
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Designation: D7736 − 19
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
1
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* ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to
1.1 This test method covers the determination of free acids
Determine the Precision of a Test Method
and glycol esters in ethylene glycol by titration.
1.2 Laboratory testing has proved that the test method can
3. Terminology
also be used on propylene glycol and 1,3-propanediol.
3.1 Definitions:
1.3 Thistestmethodistypicallyusedonglycolsusedforthe
3.1.1 For definitions of terms used in this test method, refer
manufactureofenginecoolant.Itcannotbeusedonformulated
to Terminology D4725.
engine coolant. The inhibitors will interfere with the determi-
nation. 4. Summary of Test Method
1.4 The values stated in SI units are to be regarded as 4.1 This test method is used to determine the acid and ester
standard. No other units of measurement are included in this content of ethylene glycol by titration.The sample is titrated to
standard. the phenolphthalein end point with 0.02 N NaOH to determine
the acidity. Then a known amount of base is added and the
1.5 This standard does not purport to address all of the
sample is heated at 100 °C to hydrolyze the esters. It is then
safety concerns, if any, associated with its use. It is the
back-titrated with 0.02 N sulfuric acid to determine the ester
responsibility of the user of this standard to establish appro-
content.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
5. Significance and Use
1.6 This international standard was developed in accor-
5.1 The presence of acids or glycol esters in the ethylene
dance with internationally recognized principles on standard-
glycol used to produce engine coolant is undesirable. Under
ization established in the Decision on Principles for the
conditions in an engine cooling system, the esters can hydro-
Development of International Standards, Guides and Recom-
lyze to form glycol and an acid. The acid will react with the
mendations issued by the World Trade Organization Technical
corrosion inhibitors, thereby reducing the useful life of the
Barriers to Trade (TBT) Committee.
coolant. This method can determine the amount of acid and
glycol ester present in the ethylene glycol.
2. Referenced Documents
2
2.1 ASTM Standards:
6. Interferences
D1176 Practice for Sampling and Preparing Aqueous Solu-
6.1 This test method is based on a color change titration.
tions of Engine Coolants orAntirusts forTesting Purposes
Glycol with a strong color could interfere with the results of
D1193 Specification for Reagent Water
this method.
D4725 Terminology for Engine Coolants and Related Fluids
E177 Practice for Use of the Terms Precision and Bias in 6.2 High pH recycled glycols streams will affect the results
of this test method.
1
This test method is under the jurisdiction ofASTM Committee D15 on Engine
7. Apparatus
Coolants and Related Fluids and is the direct responsibility of Subcommittee
7.1 250 mL Borosilicate Glass Bottles, with screw caps.
D15.04 on Chemical Properties.
Current edition approved April 1, 2019. Published April 2019. Originally
approved in 2011. Last previous edition approved in 2018 as D7736–12 (2018).
8. Reagents and Materials
DOI: 10.1520/D7736–19.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenol-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
phthalein in methanol or ethanol and dilute to 100 mL.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
*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 − 19
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 25.0 Weigh the sample to the
from the bath and cool to room temperature. When cool, add 3
0.10 to 0.20 10.0 nearest 0.1 g into the
A drops of phenolphthalein solution to each and titrate with 0.02
0.20 to 0.50 5
...
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 − 12 (Reapproved 2018) D7736 − 19
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
1
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 Scope*
1.1 This test method covers the determination of free acids and glycol esters in ethylene glycol by titration.
1.2 Laboratory testing has proved that the test method can also be used on propylene glycol and 1,3-propanediol.
1.3 This test method is fortypically used on ethylene glycol glycols used for the manufacture of engine coolant. It can not cannot
be used on formulated engine coolant. The inhibitors will interfere with the determination.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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.
1.6 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:
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
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 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.
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.
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 March 1, 2018April 1, 2019. Published March 2018April 2019. Originally approved in 2011. Last previous edition approved in 20122018 as
D7736 - 12.D7736–12 (2018). DOI: 10.1520/D7736-12R18.10.1520/D7736–19.
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 ----------------------
D7736 − 19
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 Bottles, with screw caps.
8. Reagents and Materials
8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenolphthalein in methanol or ethanol and dilute to 100 mL.
8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
8.3 Sulfuric Acid (H SO ), 0.02 N in water.
2 4
8.4 Purity of Water
...
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