ASTM D7736-11

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Designation:D7736–11
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
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 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
1.1 This test method covers the determination of free acids
content.
and glycol esters in ethylene glycol by titration.
1.2 This test method is for used on ethylene glycol used for
5. Significance and Use
the manufacture of engine coolant. It can not be used on
5.1 The presence of acids or glycol esters in the ethylene
formulated engine coolant. The inhibitors will interfere with
glycol used to produce engine coolant is undesirable. Under
the determination.
conditions in an engine cooling system, the esters can hydro-
1.3 The values stated in SI units are to be regarded as
lyze to form glycol and an acid. The acid will react with the
standard. No other units of measurement are included in this
corrosion inhibitors, thereby reducing the useful life of the
standard.
coolant. This method can determine the amount of acid and
1.4 This standard does not purport to address all of the
glycol ester present in the ethylene glycol.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
6. Interferences
priate safety and health practices and determine the applica-
6.1 This test method is based on a color change titration.
bility of regulatory limitations prior to use.
Glycol with a strong color could interfere with the results of
2. Referenced Documents this method.
2 6.2 High pH recycled glycols streams will affect the results
2.1 ASTM Standards:
of this test method.
D1176 Practice for Sampling and Preparing Aqueous Solu-
tions of Engine Coolants orAntirusts for Testing Purposes
7. Apparatus
D1193 Specification for Reagent Water
7.1 250 mL Borosilicate Glass Bottles, with screw caps.
D4725 Terminology for Engine Coolants
8. Reagents and Materials
3. Terminology
8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenol-
3.1 Definitions:
phthalein in methanol or ethanol and dilute to 100 mL.
3.1.1 For definitions of terms used in this test method, refer
8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
to Terminology D4725.
8.3 Sulfuric Acid (H SO ), 0.02 N in water.
2 4
8.4 Purity of Water—Unless otherwise indicated, references
4. Summary of Test Method
to water shall be understood to mean reagent water as defined
4.1 This test method is used to determine the acid and ester
by Type II or III of Specification D1193.
content of ethylene glycol by titration.The sample is titrated to
8.5 Purity of Reagents—Reagent grade chemicals shall be
the phenolphthalein end point with 0.02 N NaOH to determine
used in all tests. Unless otherwise indicated, it is intended that
the acidity. Then a known amount of base is added and the
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
This test method is under the jurisdiction ofASTM Committee D15 on Engine where such specifications are available. Other grades may be
Coolants and is the direct responsibility of Subcommittee D15.04 on Chemical
Properties.
Current edition approved June 1, 2011. Published August 2011. DOI: 10.1520/ Reagent Chemicals, American Chemical Society Specifications, American
D7736–11. Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
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contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
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D7736–11
used, provided it is first ascertained that the reagent is of The weight of the bo
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