ASTM D7437-23

Standard Test Method for Temperature and Hard Water Stability of Engine Coolants

SIGNIFICANCE AND USE
4.1 This test method provides information on the stability of the engine coolant concentrate when stored at elevated temperatures for two weeks. These test conditions might simulate the conditions that a product would be subjected to in transit and storage in warehouses before delivery to the customer.  
4.2 This test method provides information on the stability of an engine coolant diluted with synthetic hard water at elevated temperatures. This test method provides a laboratory method to test the sensitivity of the engine coolant to hard water.
SCOPE
1.1 This test method covers a simple glassware-type procedure for evaluating the effects of temperature and hard water on the stability of engine coolants at elevated temperatures under controlled laboratory conditions.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 71.100.45 - Refrigerants and antifreezes
• Technical Committee: D15 - Engine Coolants and Related Fluids
• Drafting Committee: D15.06 - Glassware Performance Tests

Relations

• Replaces: ASTM D7437-08(2019) - Standard Test Method for Temperature and Hard Water Stability of Engine Coolants
• Effective Date: 01-Nov-2023

Overview

ASTM D7437-23 - Standard Test Method for Temperature and Hard Water Stability of Engine Coolants - is a key international standard developed by ASTM International. This test method assesses how engine coolant concentrates and their solutions react to elevated temperature conditions and exposure to hard water. Its procedures replicate challenging transportation and storage scenarios that coolants may face before reaching the customer. This standard serves manufacturers, laboratories, and quality assurance professionals who require a reliable laboratory method for evaluating the long-term stability and compatibility of engine coolant products.

Key Topics

• Engine Coolant Stability: Measures stability of coolant concentrates subjected to sustained high temperatures, providing valuable data about their shelf life and storage robustness.
• Hard Water Sensitivity: Evaluates how diluted coolants react when mixed with synthetic hard water at elevated temperatures, simulating possible field or application conditions.
• Test Methodology: Employs a straightforward glassware-centric procedure under strictly controlled laboratory conditions.
• Precipitate Observation: Records any precipitation or gelation after exposure to specific conditions, which may indicate incompatibilities or degradation in the coolant’s composition.
• Reporting Requirements: Specifies comprehensive documentation of sample appearance, changes, and the amount of any precipitate, both before and after testing phases.
• Safety and Compliance: Highlights the necessity for adhering to relevant safety, health, and environmental practices when executing the test.

Applications

The ASTM D7437-23 standard is directly applicable in several critical areas:

• Product Development: Engine coolant manufacturers use this method during R&D to formulate products with improved durability under varying storage and application scenarios.
• Quality Control: Provides a basis for ongoing quality assurance in production settings, helping to ensure that marketed coolant products maintain stability, even when exposed to fluctuating temperatures or hard water.
• Supplier Evaluation: Allows OEMs and distributors to validate the resilience of coolants supplied by third parties, minimizing risk of product failure in the field.
• Regulatory and Compliance Testing: Assists in meeting international requirements for the sale and distribution of engine coolants, specifically related to stability during storage, transport, and use.
• Technical Comparisons: Facilitates benchmarking of different coolant formulations by providing a standardized reference for thermal and hard water stability.

Related Standards

ASTM D7437-23 uses or refers to several related standards that support its methodology:

• ASTM D1176 - Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• ASTM D1193 - Specification for Reagent Water
• ASTM E288 - Specification for Laboratory Glass Volumetric Flasks
• BS 5117-1.5:1992 - Coolant Hard Water Stability Test (British Standard)
• BSI BS ISO 5725-2 - Accuracy (Trueness and Precision) of Measurement Methods and Results

By following ASTM D7437-23, organizations can ensure their engine coolants meet rigorous international standards for temperature and hard water stability, enhancing product reliability and customer satisfaction across global markets.

Keywords: engine coolant stability, temperature stability, hard water sensitivity, ASTM D7437-23, coolant testing, laboratory procedure, coolant precipitation, quality control, coolant compatibility, international standard

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: D7437 − 23
Standard Test Method for
Temperature and Hard Water Stability of Engine Coolants
This standard is issued under the fixed designation D7437; 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* 3. Summary of Test Method
3.1 A sample engine coolant concentrate is kept at 60 °C in
1.1 This test method covers a simple glassware-type proce-
a controlled oven for 14 days and then cooled to room
dure for evaluating the effects of temperature and hard water on
the stability of engine coolants at elevated temperatures under temperature and inspected. Synthetic hard water is then added
and the test solution is returned to an oven set at 90 °C for 14
controlled laboratory conditions.
days. At the end of this period, the test engine coolant solution
1.2 The values stated in SI units are to be regarded as
is removed, cooled, and inspected. The cooled sample is
standard. The values given in parentheses after SI units are
centrifuged and any precipitate treated with methanol. The
provided for information only and are not considered standard.
volume of any precipitate left after the methanol wash is
1.3 This standard does not purport to address all of the
decanted is recorded.
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.1 This test method provides information on the stability of
mine the applicability of regulatory limitations prior to use.
the engine coolant concentrate when stored at elevated tem-
1.4 This international standard was developed in accor-
peratures for two weeks. These test conditions might simulate
dance with internationally recognized principles on standard-
the conditions that a product would be subjected to in transit
ization established in the Decision on Principles for the
and storage in warehouses before delivery to the customer.
Development of International Standards, Guides and Recom-
4.2 This test method provides information on the stability of
mendations issued by the World Trade Organization Technical
an engine coolant diluted with synthetic hard water at elevated
Barriers to Trade (TBT) Committee.
temperatures. This test method provides a laboratory method to
test the sensitivity of the engine coolant to hard water.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solu-
5.1 Graduated Cylinder, of capacity 50 mL 6 0.50 mL.
tions of Engine Coolants or Antirusts for Testing Purposes
5.2 Graduated Conical Centrifuge Tubes, of capacity
D1193 Specification for Reagent Water
100 mL with stoppers.
E288 Specification for Laboratory Glass Volumetric Flasks
3 5.3 Forced Ventilation Oven, capable of being maintained at
2.2 British Standards:
temperatures of 60 °C 6 2 °C and 90 °C 6 2 °C.
BS 5117-1.5:1992 Coolant Hard Water Stability Test
5.4 Centrifuge—capable of generating a relative centrifugal
BSI BS ISO 5725-2 Accuracy (Trueness and Precision) of
force of 900.
Measurement Methods and Results–Part 2: Basic Method
for the Determination of Repeatability and Reproducibil- 2
Relative centrifugal force 5 ~v/1335! d (1)
ity of a Standard Measurement Method
where:
v = rotational velocity (r/min) and,
This test method is under the jurisdiction of ASTM Committee D15 on Engine
d = diameter (mm) between the ends of the centrifuge tubes
Coolants and Related Fluids and is the direct responsibility of Subcommittee
at the point of maximum swing.
D15.06 on Glassware Performance Tests.
Current edition approved Nov. 1, 2023. Published November 2023. Originally
5.5 Pipette, of capacity 20 mL 6 0.50 mL.
approved in 2008. Last previous edition approved in 2019 as D7437 – 08 (2019).
5.6 Volumetric Balance, one-mark, 1000 mL (compliant
DOI: 10.1520/D7437–23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
with Specification E288, Class B requirements).
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
6. Reagents and Materials
the ASTM website.
6.1 Purity of Reagents—Reagent grade chemicals shall be
Available from British Standards Institution (BSI), 389 Chiswick High Rd.,
London W4 4AL, U.K., http://www.bsigroup.com. used in all tests. Unless otherwise indicated, it is intended that
*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
D7437 − 23
all reagents conform to the specification of the Committee on 9.5 Inspect the cooled solution and note any gelation or
Analytical Reagents of the American Chemical Society where precipitation. Centrifuge the cooled solution, using a relative
such specifications are available. Other grades may be used, centrifugal force of 900, for 15 min. Carefully decant the liquor
provided it is first ascertained that the reagent is of sufficiently from any precipitate present at the bottom of the centrifuge
high purity to permit its use without lessening the accuracy of tubes.
the determination.
9.6 Using the 20 mL pipette, add 20 mL of the methanol to
6.2 Purity of Water—Unless otherwise indicated, references the precipitate in the centrifuge tubes and shake vigorously
to water shall be understood to mean reagent water as defined until the precipitate is dislodged to ensure thorough washing.
by Type IV of Specification D1193. Recentrifuge for 15 min. Decant the methanol from any
precipitate present at the bottom of the centrifuge tubes.
6.3 Synthetic Hard Water Stock Solution—Prep
...

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: D7437 − 08 (Reapproved 2019) D7437 − 23
Standard Test Method for
Temperature and Hard Water Stability of Engine Coolants
This standard is issued under the fixed designation D7437; 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 a simple glassware-type procedure for evaluating the effects of temperature and hard water on the
stability of engine coolants at elevated temperatures under controlled laboratory conditions.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered 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.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D1176 Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
D1193 Specification for Reagent Water
E288 Specification for Laboratory Glass Volumetric Flasks
2.2 British Standards:
BS 5117-1.5:1992 Coolant Hard Water Stability Test
BSI BS ISO 5725-2 Accuracy (Trueness and Precision) of Measurement Methods and Results–Part 2: Basic Method for the
Determination of Repeatability and Reproducibility of a Standard Measurement Method
3. Summary of Test Method
3.1 A sample engine coolant concentrate is kept at 60 °C in a controlled oven for 14 days and then cooled to room temperature
and inspected. Synthetic hard water is then added and the test solution is returned to an oven set at 90 °C for 14 days. At the end
of this period, the test engine coolant solution is removed, cooled, and inspected. The cooled sample is centrifuged and any
precipitate treated with methanol. The volume of any precipitate left after the methanol wash is decanted is recorded.
This test method is under the jurisdiction of ASTM Committee D15 on Engine Coolants and Related Fluids and is the direct responsibility of Subcommittee D15.06 on
Glassware Performance Tests.
Current edition approved Oct. 1, 2019Nov. 1, 2023. Published October 2019November 2023. Originally approved in 2008. Last previous edition approved in 20132019
as D7437D7437 – 08 (2019).–08 (2013). DOI: 10.1520/D7437–08R19. DOI: 10.1520/D7437–23.
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’s Document Summary page on the ASTM website.
Available from British Standards Institution (BSI), 389 Chiswick High Rd., London W4 4AL, U.K., http://www.bsigroup.com.
*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
D7437 − 23
4. Significance and Use
4.1 4.1 This test method provides information on the stability of the engine coolant concentrate when stored at elevated
temperatures for two weeks. These test conditions might simulate the conditions that a product would be subjected to in transit
and storage in warehouses before delivery to the customer.
4.2 This test method provides information on the stability of an engine coolant diluted with synthetic hard water at elevated
temperatures. This test method provides a laboratory method to test the sensitivity of the engine coolant to hard water.
5. Apparatus
5.1 Graduated Cylinder, of capacity 50 6 0.50 mL.50 mL 6 0.50 mL.
5.2 Graduated Conical Centrifuge Tubes, of capacity 100 mL 100 mL with stoppers.
5.3 Forced Ventilation Oven, capable of being maintained at temperatures of 6060 °C 6 2 °C and 9090 °C 6 2 °C.
5.4 Centrifuge—capable of generating a relative centrifugal force of 900.
Relative centrifugal force 5 v/1335 d (1)
~ !
where:
v = rotational velocity (r/min) and,
d = diamter (mm) between the ends of the centrifuge tubes at the point of maximum swing.
d = diameter (mm) between the ends of the centrifuge tubes at the point of maximum swing.
5.5 Pipette, of capacity 2020 mL 6 0.50 mL.
5.6 Volumetric Balance, one-mark, 1000 mL (compliant with Specification E288, Class B requirements).
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
reagents conform to the specification 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 the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
6.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type
IV of Specification D1193.
6.3 Synthetic Hard Water Stock Solution—Prepare a stock solution by dissolving 44.10 g of calcium chloride dehydrate (CaCl
2H O) in water in a 1000 mL one-mark volumetric flask and diluting to the mark with water. Before use, dilute this stock solution
1:50 with water.
6.4 Methanol, CH OH (Warning—See 7.1.)
7. Hazards
7.1 Methanol—Poison, extremely flammable, harmful if swallowed or inhaled. Flash point of 12 °C.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent
...