ASTM D3634-21

Standard Test Method for Trace Chloride Ion in Engine Coolants

SIGNIFICANCE AND USE
4.1 This test method permits the determination of very low levels of chloride ion in engine coolants containing the common corrosion inhibitor, mercaptobenzothiazole, or related mercaptans, which would normally interfere with the titration by also forming insoluble silver salts with silver nitrate.
SCOPE
1.1 This test method covers the determination of chloride ion in engine coolants in the range from 5 ppm to 200 ppm in the presence of up to 0.6 weight % mercaptobenzothiazole.  
1.2 Other materials that react with silver ion will interfere.  
1.3 Chloride in engine coolants containing an aryltriazole instead of mercaptobenzothiazole can be determined directly by this test method without pretreatment with hydrogen peroxide.  
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. Specific hazards statements are given in Section 7.  
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.

General Information

• Status: Published
• Publication Date: 31-Oct-2021
• ICS: 71.100.45 - Refrigerants and antifreezes
• Technical Committee: D15 - Engine Coolants and Related Fluids
• Drafting Committee: D15.04 - Chemical Properties

Relations

• Refers: ASTM D1176-14(2019) - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 01-Oct-2019
• Refers: ASTM D1176-14 - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 01-Apr-2014
• Refers: ASTM D1176-98(2008) - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 01-Apr-2008
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1176-98(2002) - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 10-Apr-1998
• Refers: ASTM D1176-98 - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 10-Apr-1998

Overview

ASTM D3634-21: Standard Test Method for Trace Chloride Ion in Engine Coolants provides a precise method for determining low concentrations of chloride ion in engine coolants, particularly in formulations containing mercaptobenzothiazole and related mercaptans as corrosion inhibitors. This standard covers analysis in the range from 5 ppm to 200 ppm chloride, even in the presence of up to 0.6% mercaptobenzothiazole by weight. Accurate measurement of trace chloride is essential, as excessive chloride can contribute to corrosion and reduce coolant effectiveness in automotive and industrial engines.

ASTM D3634-21 is developed and maintained by ASTM Committee D15 on Engine Coolants and Related Fluids and serves as a key reference for laboratories, coolant manufacturers, and quality assurance professionals involved in engine coolant testing.

Key Topics

• Trace Chloride Measurement: The standard details a potentiometric titration method using standard silver nitrate solution to determine chloride levels, even when common interfering agents like mercaptobenzothiazole are present.
• Interference Management: The procedure includes pretreatment with hydrogen peroxide to oxidize interfering mercaptans, enabling accurate results despite the presence of substances that could otherwise form insoluble silver salts.
• Applicability to Alternative Inhibitors: For engine coolants containing aryltriazoles instead of mercaptobenzothiazole, the method can be applied directly, without additional pretreatment steps.
• Standardized Reporting: Results are reported in parts per million (ppm) chloride, ensuring consistency across the industry. The method emphasizes the use of SI units exclusively.
• Precision and Reproducibility: The method yields reproducible chloride ion determinations, with repeatability of 5 ppm for values within the 55-200 ppm range.
• Laboratory Practice and Safety: Users are reminded to adhere to rigorous laboratory safety, health, and environmental practices, with specific hazard statements addressing the handling of chemicals like glacial acetic acid, hydrogen peroxide, and silver nitrate.

Applications

• Quality Control in Coolant Manufacturing: Manufacturers utilize ASTM D3634-21 to verify that chloride levels in engine coolants are within specifications, thereby preventing premature corrosion and engine damage.
• Laboratory Analysis: Accredited laboratories apply this method for routine coolant analysis, particularly in environments where sensitive determination of trace ions is necessary.
• Product Development and Compliance: Engine coolant formulators reference this standard during research and development to ensure new products meet industry chloride limits.
• Regulatory and Warranty Compliance: OEMs and consumer goods companies may require proof of adherence to ASTM D3634-21 to minimize warranty claims or regulatory issues associated with coolant performance and corrosion.

Related Standards

• ASTM D1176 - Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• ASTM D1193 - Specification for Reagent Water
• ASTM E200 - Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis

By following ASTM D3634-21, users ensure reliable, comparable data across the engine coolant industry, contributing to enhanced equipment longevity and optimal engine performance. This standard supersedes earlier versions and aligns with international principles on standardization, making it a globally recognized tool for trace chloride testing in coolant quality control.

Standards Content (Sample)

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.
Designation: D3634 − 21
Standard Test Method for
Trace Chloride Ion in Engine Coolants
This standard is issued under the fixed designation D3634; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope E200 Practice for Preparation, Standardization, and Storage
of Standard and Reagent Solutions for ChemicalAnalysis
1.1 This test method covers the determination of chloride
2.2 Manufacturing Chemists’ Association Document:
ion in engine coolants in the range from 5 ppm to 200 ppm in
MCA Chemical Safety Data Sheet SD-53 Properties and
the presence of up to 0.6 weight % mercaptobenzothiazole.
Essential Information for Safe Handling and Use of
1.2 Other materials that react with silver ion will interfere.
Hydrogen Peroxide
1.3 Chloride in engine coolants containing an aryltriazole
3. Summary of Test Method
instead of mercaptobenzothiazole can be determined directly
by this test method without pretreatment with hydrogen per-
3.1 The sample is first treated at a pH of 12 to 13 with
oxide.
aqueous hydrogen peroxide to oxidize the mercaptobenzothi-
azoletosoluble,noninterferingsulfonate.Thetreatedsampleis
1.4 The values stated in SI units are to be regarded as
dissolved in glacial acetic acid and titrated potentiometrically
standard. No other units of measurement are included in this
with dilute standard silver nitrate solution. Since the solubility
standard.
of silver chloride in this system is sufficient to prevent
1.5 This standard does not purport to address all of the
obtaining a suitable inflection at the very low limit of the test
safety concerns, if any, associated with its use. It is the
method, some chloride is deliberately added to the glacial
responsibility of the user of this standard to establish appro-
acetic acid solvent and then corrected for by a blank titration.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4. Significance and Use
Specific hazards statements are given in Section 7.
4.1 This test method permits the determination of very low
1.6 This international standard was developed in accor-
levels of chloride ion in engine coolants containing the
dance with internationally recognized principles on standard-
commoncorrosioninhibitor,mercaptobenzothiazole,orrelated
ization established in the Decision on Principles for the
mercaptans, which would normally interfere with the titration
Development of International Standards, Guides and Recom-
by also forming insoluble silver salts with silver nitrate.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5. Apparatus
2. Referenced Documents
5.1 Manual Titrations:
5.1.1 pH Meter—An expanded scale pH meter which can be
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solu- read to 1 mV or 2 mV is desirable but not required. A silver
4 5
billet indicator electrode and glass reference electrode are
tions of Engine Coolants orAntirusts forTesting Purposes
D1193 Specification for Reagent Water used for the chloride titration. The silver electrode should be
Available from American Chemistry Council (ACC), 700 Second Street, NE,
Washington, DC 20002, https://www.americanchemistry.com.
1 4
This test method is under the jurisdiction ofASTM Committee D15 on Engine ThesolesourceofsupplyoftheSilverBilletElectrodeknowntothecommittee
Coolants and Related Fluids and is the direct responsibility of Subcommittee atthistimeisFisherScientific(www.fishersci.com,CatalogNo.13-620-122).Ifyou
D15.04 on Chemical Properties. are aware of alternative suppliers, please provide this information to ASTM
Current edition approved Nov. 1, 2021. Published November 2021. Originally International Headquarters. Your comments will receive careful consideration at a
approved in 1977. Last previous edition approved in 2015 as D3634 – 99(2015). meeting of the responsible technical committee, which you may attend.
DOI: 10.1520/D3634-21. The sole source of supply of the reference electrode known to the committee at
For referenced ASTM standards, visit the ASTM website, www.astm.org, or this time is Fisher Scientific (www.fishersci.com, Catalog No. 13-620-216). If you
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM are aware of alternative suppliers, please provide this information to ASTM
Standards volume information, refer to the standard’s Document Summary page on International Headquarters. Your comments will receive careful consideration at a
the ASTM website. meeting of the responsible technical committee, which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3634 − 21
polished occasionally with fine steel wool or scouring powder 100 mLwith water.The 0.1 N standardAgNO solution should
and thoroughly rinsed. bepreparedandstandardizedinaccordancewithSections44to
5.1.2 Buret, 10 mL, micro, Class A, calibrated in 0.02 mL 48 of Practice E200.
divisions.
6.7 Sodium Hydroxide Solution—(Warning—See 7.5.) Pre-
5.1.3 Beakers, electrolytic, 250 mL tall form.
pare a 20 mass % sodium hydroxide (NaOH) solution in water.
5.2 Automatic Titrators are satisfactory for this test method,
7. Hazards
provided they exhibit resolution and accuracy equivalent to
that specified for manual titrations.
7.1 Acetone—Extremely flammable; harmful if swallowed
or inhaled; causes irritation.
5.3 Pipets, 10 mL, 20 mL, and 100 mL, Class A.
7.2 Acetic Acid, Glacial—Poison,causessevereburns;com-
5.4 Flask, Erlenmeyer, 250 mL, with a 24/40 standard taper,
bustible; harmful if swallowed or inhaled.
female ground glass joint.
7.3 Hydrogen Peroxide Solution—Strong oxidizer; contact
5.5 Condenser—Thecondensershallbeofthewater-cooled,
withothermaterialmaycausefire;causessevereburns.Donot
reflux, glass-tube type, having a condenser jacket approxi-
tightlystoppercontainers.Forfurtherdetails,seeMCAChemi-
mately 200 mm in length. The bottom end of the condenser
cal Safety Data Sheet SD-53.
shall have a 24/40 male ground glass joint to match the
Erlenmeyer flask.
7.4 Silver Nitrate—Maybefatali
...

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: D3634 − 99 (Reapproved 2015) D3634 − 21
Standard Test Method for
Trace Chloride Ion in Engine Coolants
This standard is issued under the fixed designation D3634; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method covers the determination of chloride ion in engine coolants in the range from 55 ppm to 200 ppm in the
presence of up to 0.6 weight % mercaptobenzothiazole.
1.2 Other materials that react with silver ion will interfere.
1.3 Chloride in engine coolants containing an aryltriazole instead of mercaptobenzothiazole can be determined directly by this test
method without pretreatment with hydrogen peroxide.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 7.
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
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
D1193 Specification for Reagent Water
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 May 1, 2015Nov. 1, 2021. Published June 2015November 2021. Originally approved in 1977. Last previous edition approved in 20092015 as
D3634 – 99(2009).(2015). DOI: 10.1520/D3634-99R15.10.1520/D3634-21.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3634 − 21
E200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis
2.2 Manufacturing ChemistsChemists’ Association Document:
MCA Chemical Safety Data Sheet SD-53 SD-53Properties and Essential Information for Safe Handling and Use of Hydrogen
Peroxide
3. Summary of Test Method
3.1 The sample is first treated at a pH of 12 to 13 with aqueous hydrogen peroxide to oxidize the mercaptobenzothiazole to soluble,
noninterfering sulfonate. The treated sample is dissolved in glacial acetic acid and titrated potentiometrically with dilute standard
silver nitrate solution. Since the solubility of silver chloride in this system is sufficient to prevent obtaining a suitable inflection
at the very low limit of the test method, some chloride is deliberately added to the glacial acetic acid solvent and then corrected
for by a blank titration.
4. Significance and Use
4.1 This test method permits the determination of very low levels of chloride ion in engine coolants containing the common
corrosion inhibitor, mercaptobenzothiazole, or related mercaptans, which would normally interfere with the titration by also
forming insoluble silver salts with silver nitrate.
5. Apparatus
5.1 Manual Titrations:
5.1.1 pH Meter—An expanded scale pH meter which can be read to 11 mV or 2 mV is desirable but not required. A silver billet
4 5
indicator electrode and glass reference electrode are used for the chloride titration. The silver electrode should be polished
occasionally with fine steel wool or scouring powder and thoroughly rinsed.
5.1.2 Buret, 10-mL,10 mL, micro, Class A, calibrated in 0.02-mL0.02 mL divisions.
5.1.3 Beakers, electrolytic, 250-mL250 mL tall form.
5.2 Automatic Titrators are satisfactory for this test method, provided they exhibit resolution and accuracy equivalent to that
specified for manual titrations.
5.3 Pipets, 10, 20,10 mL, 20 mL, and 100-mL,100 mL, Class A.
5.4 Flask, Erlenmeyer, 250 mL, with a 24/40 standard taper, female ground glass joint.
5.5 Condenser—The condenser shall be of the water-cooled, reflux, glass-tube type, having a condenser jacket approximately 200
mm in length. The bottom end of the condenser shall have a 24/40 male ground glass joint to match the Erlenmeyer flask.
5.6 Flask, volumetric, 200 mL, Class A.
NOTE 1—All glassware should be thoroughly cleaned and reserved for use in this test method. Great care must be exercised to avoid contamination.
Glassware should be cleaned with chromic acid (Warning —See 7.1.) cleaning solution, then thoroughly rinsed with water, then with acetone
(Warning—See 7.2.), and dried.
6. Reagents and Materials
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
Available from the Manufacturing Chemists’ Association, 1825 Connecticut Ave., Washington, DC 20009.American Chemistry Council (ACC), 700 Second Street, NE,
Washington, DC 20002, https://www.americanchemistry.com.
The sole source of supply of the Silver Billet Electrode known to the committee at this time is Fisher Scientific (www.fishersci.com, Catalog No. 13-620-122). If you
are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of
the responsible technical committee, which you may attend.
The sole source of supply of the reference electrode known to the committee at this time is Fisher Scientific (www.fishersci.com, Catalog No. 13-620-216). If you are
aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend.
D3634 − 21
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that t
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