ASTM D7736-19

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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.
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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
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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
...