ASTM D1121-11(2020)
(Test Method)Standard Test Method for Reserve Alkalinity of Engine Coolants and Antirusts
Standard Test Method for Reserve Alkalinity of Engine Coolants and Antirusts
SIGNIFICANCE AND USE
5.1 Reserve alkalinity is the number of millilitres, to the nearest 0.1 mL of 0.100 N hydrochloric acid (HCl) required for the titration to a pH of 5.5 of a 10 mL sample of an undiluted, unused coolant, antirust, or coolant additive, and unused or used solutions thereof.
5.2 Reserve alkalinity is a term applied to engine coolants and antirusts to indicate the amount of alkaline components present in the product. It is frequently used for quality control during production, and values are often listed in specifications. When applied to used solutions, reserve alkalinity gives an approximate indication of the amount of remaining alkaline components. Unfortunately, the term is sometimes misused in that its numerical value is said to be directly related to coolant quality, the higher the number, the better the coolant. ASTM Committee D15 on Engine Coolants believes there is a need to correct some misconceptions and place the term in its proper perspective.
5.3 Reserve alkalinity (R.A.) as defined in Section 3 of this method is the number of millilitres of 0.1 N hydrochloric acid required to titrate 10 mL of concentrated coolant to a pH of 5.5. The term is not a completely accurate description of the property being measured because “alkalinity” usually refers to the pH range above 7.0.
5.4 A review of the origin of the term may be helpful in attempting to understand its proper use. When ethylene glycol was first used as an engine coolant, it was uninhibited. The need for inhibition soon became apparent and triethanolamine was incorporated. When solutions of this inhibited glycol were titrated with dilute hydrochloric acid, it was found that the steepest part of the neutralization curve occurred at a pH of about 5.0. Following the introduction of triethanolamine, other buffers, such as borates and phosphates, have been used. Titration to 5.5 was employed with these buffers which have an end point close to 5.5.
5.5 Generally, most metals in an automotive cooling...
SCOPE
1.1 This test method covers the determination of the reserve alkalinity of new, unused engine coolants, and liquid antirusts as received, of used or unused aqueous dilutions of the concentrated materials, and of aqueous dilutions of solid antirusts.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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.
1.4 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
Relations
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: D1121 − 11 (Reapproved 2020)
Standard Test Method for
1
Reserve Alkalinity of Engine Coolants and Antirusts
This standard is issued under the fixed designation D1121; 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 3.1.1 reserve alkalinity, n—a term applied to engine coolant
concentrates and antirusts to indicate the amount of alkaline
1.1 This test method covers the determination of the reserve
inhibitors present in the product.
alkalinity of new, unused engine coolants, and liquid antirusts
as received, of used or unused aqueous dilutions of the
4. Summary of Test Method
concentrated materials, and of aqueous dilutions of solid
4.1 A 10 mL sample of concentrated coolant, antirust,
antirusts.
coolantadditive,oranaqueousenginecoolantcontainingthese
1.2 The values stated in SI units are to be regarded as
products, is diluted to about 100 mL with water and titrated
standard. No other units of measurement are included in this
potentiometrically with 0.100 N hydrochloric acid to a pH of
standard.
5.5. The volume of acid used is reported to the nearest 0.1 mL.
1.3 This standard does not purport to address all of the
The concentration of coolant or additive in the coolant solution
safety concerns, if any, associated with its use. It is the shall be recorded if required, for calculation of depletion of the
responsibility of the user of this standard to establish appro-
reserve alkalinity during performance tests.
priate safety, health, and environmental practices and deter-
5. Significance and Use
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor- 5.1 Reserve alkalinity is the number of millilitres, to the
dance with internationally recognized principles on standard- nearest 0.1 mLof 0.100 N hydrochloric acid (HCl) required for
ization established in the Decision on Principles for the the titration to a pH of 5.5 of a 10 mL sample of an undiluted,
Development of International Standards, Guides and Recom- unused coolant, antirust, or coolant additive, and unused or
mendations issued by the World Trade Organization Technical used solutions thereof.
Barriers to Trade (TBT) Committee.
5.2 Reserve alkalinity is a term applied to engine coolants
and antirusts to indicate the amount of alkaline components
2. Referenced Documents
present in the product. It is frequently used for quality control
2
2.1 ASTM Standards: during production, and values are often listed in specifications.
D1123 Test Methods for Water in Engine Coolant Concen- When applied to used solutions, reserve alkalinity gives an
trate by the Karl Fischer Reagent Method
approximate indication of the amount of remaining alkaline
D1176 Practice for Sampling and Preparing Aqueous Solu- components. Unfortunately, the term is sometimes misused in
tions of Engine Coolants orAntirusts forTesting Purposes
that its numerical value is said to be directly related to coolant
D1287 TestMethodforpHofEngineCoolantsandAntirusts quality, the higher the number, the better the coolant. ASTM
Committee D15 on Engine Coolants believes there is a need to
3. Terminology correct some misconceptions and place the term in its proper
perspective.
3.1 Definitions:
5.3 Reserve alkalinity (R.A.) as defined in Section 3 of this
method is the number of millilitres of 0.1 N hydrochloric acid
requiredtotitrate10mLofconcentratedcoolanttoapHof5.5.
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This test method is under the jurisdiction ofASTM Committee D15 on Engine
The term is not a completely accurate description of the
Coolants and Related Fluids and is the direct responsibility of Subcommittee
D15.04 on Chemical Properties.
property being measured because “alkalinity” usually refers to
Current edition approved Jan. 1, 2020. Published January 2020. Originally
the pH range above 7.0.
approved in 1950. Last previous edition approved in 2011 as D1121–11. DOI:
10.1520/D1121–11R20.
5.4 A review of the origin of the term may be helpful in
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
attempting to understand its proper use. When ethylene glycol
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
was first used as an engine coolant, it was uninhibited. The
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. need for
...
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