ASTM D6660-01(2023)

Standard Test Method for Freezing Point of Aqueous Ethylene Glycol Base Engine Coolants by Automatic Phase Transition Method

SIGNIFICANCE AND USE
5.1 The freezing point of an engine coolant indicates the coolant freeze protection.  
5.2 The freezing point of an engine coolant may be used to determine the approximate glycol content, provided the glycol type is known.  
5.3 Freezing point as measured by Test Method D1177 or approved alternative method is a requirement in Specifications D3306 and D6210.  
5.4 This test method provides results that are equivalent to Test Method D1177 and expresses results to the nearest 0.1 °C with improved reproducibility over Test Method D1177.  
5.5 This test method determines the freezing point in a shorter period of time than Test Method D1177.  
5.6 This test method removes most of the operator time and judgement required by Test Method D1177.
SCOPE
1.1 This test method covers the determination of the freezing point of an aqueous engine coolant solution.  
1.2 This test method is designed to cover ethylene glycol base coolants up to a maximum concentration of 60 % (v/v) in water; however, the ASTM interlaboratory study mentioned in 12.2 has only demonstrated the test method with samples having a concentration range of 40 % to 60 % (v/v) water.
Note 1: Where solutions of specific concentrations are to be tested, they shall be prepared from representative samples as directed in Practice D1176. Secondary phases separating on dilution need not be separated.
Note 2: The products may also be marketed in a ready-to-use form (prediluted).  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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. Some specific hazards statements are given in 7.3.  
1.5 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-Aug-2023
• ICS: 19.040 - Environmental testing
• ICS: 71.100.45 - Refrigerants and antifreezes
• Technical Committee: D15 - Engine Coolants and Related Fluids
• Drafting Committee: D15.03 - Physical 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 D3306-19 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 01-Apr-2019
• Refers: ASTM D1177-16 - Standard Test Method for Freezing Point of Aqueous Engine Coolants
• Effective Date: 01-Apr-2016
• 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 D1177-12 - Standard Test Method for Freezing Point of Aqueous Engine Coolants
• Effective Date: 01-Oct-2012
• Refers: ASTM D3306-10 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 01-Apr-2010
• Refers: ASTM D3306-09 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 01-Sep-2009
• Refers: ASTM D6210-08 - Standard Specification for Fully-Formulated Glycol Base Engine Coolant for Heavy-Duty Engines
• Effective Date: 01-Oct-2008
• Refers: ASTM D3306-08a - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 15-May-2008
• 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 D3306-08 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 15-Jan-2008
• Refers: ASTM D1177-07 - Standard Test Method for Freezing Point of Aqueous Engine Coolants
• Effective Date: 01-Apr-2007
• Refers: ASTM D6210-06 - Standard Specification for Fully-Formulated Glycol Base Engine Coolant for Heavy-Duty Engines
• Effective Date: 01-Aug-2006
• Refers: ASTM D3306-05 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 01-Oct-2005
• Refers: ASTM D1177-05 - Standard Test Method for Freezing Point of Aqueous Engine Coolants
• Effective Date: 01-Jun-2005

Overview

ASTM D6660-01(2023) specifies the standard test method for determining the freezing point of aqueous ethylene glycol base engine coolants using an automatic phase transition method. Accurate measurement of the freezing point is critical for evaluating engine coolant freeze protection, ensuring vehicle and engine system performance in varying environmental conditions. This automated method delivers results with high precision and reduced operator intervention, streamlining laboratory workflows and enabling quicker decision-making for manufacturers and laboratories involved in coolant quality and compliance testing.

Key Topics

• Freeze Protection Assessment: The freezing point indicates the effectiveness of an engine coolant in protecting systems from freeze-related damage.
• Glycol Content Estimation: The freezing point, with known glycol type, helps estimate the glycol concentration in the coolant.
• Automation and Reproducibility: This method automates the phase transition determination, providing results equivalent to ASTM D1177, but with improved reproducibility and reduced operator bias.
• Test Range and Scope: Applicable to ethylene glycol base coolants with concentrations up to 60% by volume in water, with demonstrated reliability for concentrations between 40% and 60%.
• Measurement Precision: Delivers results to the nearest 0.1 °C, ensuring high-resolution reporting for specification compliance.

Applications

• Automotive Industry: Used by automotive manufacturers and service providers to test the freeze protection capability of new and in-service engine coolants, both concentrated and ready-to-use formulations.
• Coolant Formulation and Quality Control: Supports coolant producers and laboratories in meeting requirements of specifications such as ASTM D3306 (glycol base engine coolant for automotive service) and ASTM D6210 (fully-formulated coolant for heavy-duty engines).
• Predictive Maintenance: Enables maintenance personnel to monitor coolant properties and perform timely coolant replacement or adjustments.
• Research and Development: Facilitates research in coolant formulation, allowing rapid screening of new product blends and improved product compliance.

Related Standards

• ASTM D1177: Standard Test Method for Freezing Point of Aqueous Engine Coolants. The manual benchmark for comparison; D6660 automates and enhances this process.
• ASTM D3306: Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service. Defines key coolant properties, including freeze point.
• ASTM D6210: Specification for Fully-Formulated Glycol Base Engine Coolant for Heavy-Duty Engines. This standard incorporates freezing point as a critical compliance parameter.
• ASTM D1176: Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes. Guidance on representative sample preparation for freeze point testing.

Practical Value

ASTM D6660-01(2023) helps ensure the safety, reliability, and performance of engine cooling systems by providing a quick, objective, and reproducible method for freeze point determination. The automation reduces human error, improves laboratory productivity, and aligns with international standardization principles for consistent global application. This is vital for regulatory compliance, product development, and operational efficiency across the automotive and coolant manufacturing industries.

Keywords: ASTM D6660, freezing point test, ethylene glycol coolant, engine coolant analysis, phase transition method, coolant freeze protection, automated freeze point measurement, ASTM standards, automotive coolant testing.

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: D6660 − 01 (Reapproved 2023)
Standard Test Method for
Freezing Point of Aqueous Ethylene Glycol Base Engine
Coolants by Automatic Phase Transition Method
This standard is issued under the fixed designation D6660; 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 tions of Engine Coolants or Antirusts for Testing Purposes
D1177 Test Method for Freezing Point of Aqueous Engine
1.1 This test method covers the determination of the freez-
Coolants
ing point of an aqueous engine coolant solution.
D3306 Specification for Glycol Base Engine Coolant for
1.2 This test method is designed to cover ethylene glycol
Automobile and Light-Duty Service
base coolants up to a maximum concentration of 60 % (v ⁄v) in
D6210 Specification for Fully-Formulated Glycol Base En-
water; however, the ASTM interlaboratory study mentioned in
gine Coolant for Heavy-Duty Engines
12.2 has only demonstrated the test method with samples
having a concentration range of 40 % to 60 % (v ⁄v) water.
3. Terminology
NOTE 1—Where solutions of specific concentrations are to be tested, 3.1 Definitions of Terms Specific to This Standard:
they shall be prepared from representative samples as directed in Practice
3.1.1 automatic phase transition method, n—in this
D1176. Secondary phases separating on dilution need not be separated.
standard, the procedures of automatically cooling an engine
NOTE 2—The products may also be marketed in a ready-to-use form
coolant sample until solid crystals appear, followed by con-
(prediluted).
trolled warming and recording the temperature at which the
1.3 The values stated in SI units are to be regarded as
crystals redissolve into the liquid phase.
standard. No other units of measurement are included in this
3.1.2 freezing point, n—the temperature at which crystalli-
standard.
zation begins in the absence of supercooling, or the maximum
1.4 This standard does not purport to address all of the
temperature reached immediately after initial crystal formation
safety concerns, if any, associated with its use. It is the
in the case of supercooling, or the temperature at which solid
responsibility of the user of this standard to establish appro-
crystals, formed on cooling, disappear when the temperature of
priate safety, health, and environmental practices and deter-
the specimen is allowed to rise.
mine the applicability of regulatory limitations prior to use.
3.1.3 peltier device, n—a solid state thermoelectric device
Some specific hazards statements are given in 7.3.
constructed with dissimilar semiconductor materials, config-
1.5 This international standard was developed in accor-
ured in such a way that it will transfer heat to and away from
dance with internationally recognized principles on standard-
a test specimen dependent on the direction of electric current
ization established in the Decision on Principles for the
applied to the device.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4. Summary of Test Method
Barriers to Trade (TBT) Committee.
4.1 A specimen is cooled by a Peltier device while continu-
2. Referenced Documents ously being illuminated by a light source. The specimen is
2 continuously monitored by an array of optical detectors for the
2.1 ASTM Standards:
first formation of crystals. Once the crystals are formed, the
D1176 Practice for Sampling and Preparing Aqueous Solu-
specimen is then warmed at controlled rates until all the
crystals return to the liquid phase. The detectors are sufficient
in number to ensure that any crystals are detected. The
This test method is under the jurisdiction of ASTM Committee D15 on Engine
Coolants and Related Fluids and is the direct responsibility of Subcommittee
specimen temperature at which the crystals return to the liquid
D15.03 on Physical Properties.
phase is recorded by the temperature sensor as the freezing
Current edition approved Sept. 1, 2023. Published September 2023. Originally
point.
approved in 2001. Last previous edition approved in 2019 as D6660 – 01 (2019).
DOI: 10.1520/D6660-01R23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 5. Significance and Use
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.1 The freezing point of an engine coolant indicates the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. coolant freeze protection.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6660 − 01 (2023)
5.2 The freezing point of an engine coolant may be used to 8. Preparation of Apparatus
determine the approximate glycol content, provided the glycol
8.1 Install the analyzer for operation in accordance with
type is known.
manufacturer’s instructions.
5.3 Freezing point as measured by Test Method D1177 or
8.2 Make liquid cooling media connections and ensure that
approved alternative method is a requirement in Specifications
they do not leak.
D3306 and D6210.
8.3 Turn on the liquid cooling media.
5.4 This test method provides results that are equivalent to
8.4 Turn on the main power switch of the analyzer. After the
Test Method D1177 and expresses results to the nearest 0.1 °C
automatic self diagnostics start-up sequence is completed, the
with improved reproducibility over Test Method D1177.
instrument will display a “READY” message.
5.5 This test method determines the freezing point in a
shorter period of time than Test Method D1177.
9. Calibration and Standardization
5.6 This test method removes most of the operator time and
9.1 Ensure that all of the manufacturer’s instructions for
judgement required by Test Method D1177.
calibrating, checking and operating the apparatus are followed.
9.2 A sample with a mutually agreed upon freezing point
6. Apparatus
can be used to verify performance of the apparatus.
6.1 Automatic Apparatus —The apparatus described in this
method consists of a test chamber controlled by a micropro-
10. Procedure
cessor that is capable of cooling and heating the test specimen,
10.1 Open the test chamber lid and clean the specimen cup
optically observing the appearance and disappearance of solid
inside the test chamber with a cotton swab.
crystals and recording the temperature of the specimen.
10.2 Use the pipette to deliver 0.15 mL 6 0.01 mL of
6.2 The apparatus shall be equipped with a specimen cup,
specimen into the specimen cup. Clean the specimen out of the
optical detector array, light source, digital display, Peltier
cup by using a cotton swab. The cup should be cleaned to the
device and a specimen temperature measuring device.
point where no visible droplets of specimen remain in the cup.
6.3 The temperature measuring device in the specimen cup
10.3 Repeat step 10.2.
shall be capable of measuring the temperature of the test
10.4 Carefully measure 0.15 mL 6 0.01 mL of specimen
specimen from –80 °C to +50 °C at a resolution of 0.1 °C.
into the specimen cup.
6.4 The apparatus shall be equipped with fittings to permit
10.5 Close and lock the test chamber lid.
the circulation of liquid cooling media to remove heat gener-
ated by the Peltier device and other electronic components of
10.6 Push the “RUN” button located on the front panel of
the apparatus.
the apparatus. The specimen is cooled by the Peltier device
while the appearance of solid crystals is continuously moni-
7. Reagents and Materials
tored by the optical detectors. The temperature of the specimen
7.1 Cooling Media—Liquid heat exchange media to remove is continuously monitored and displayed on the front panel of
the heat generated by the Peltier device and other electronic the apparatus. Once the crystals are detected, the specimen is
components from the apparatus. then warmed until all the crystals re-dissolve into the liquid
phase. The measurement is automatically terminated once the
NOTE 3—Some apparatus are designed to use tap water as cooling
freezing point is detected.
media to bring specimen temperature to –60 °C. To achieve cooling of
specimen to –80 °C, provide circulation of liquid cooling media at –30 °C
10.7 When the measurement is complete the freezing point
or lower to the apparatus. Refer to manufacturer’s operating instructions
value in accordance with Test Method D6660 will be displayed
on the relationship between cooling media temperature and the minimum
on the front panel of the apparatus.
specimen temperature.
10.8 Unlock and open the test chamber lid and clean the
7.2 Adjustable Volume Pipette, capable of dispensing
specimen out of the specimen cup with a cotton s
...