ASTM D4725-15(2023)

Standard Terminology for Engine Coolants and Related Fluids

SCOPE
1.1 This document covers terminology relating to engine coolants. It is intended to provide a reference for anyone seeking information on engine coolants, and also to provide a uniform set of definitions for use in preparing ASTM specifications, test methods and other standard documents.  
1.2 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.  
1.3 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: 01.040.71 - Chemical technology (Vocabularies)
• ICS: 71.100.45 - Refrigerants and antifreezes
• Technical Committee: D15 - Engine Coolants and Related Fluids
• Drafting Committee: D15.92 - Terminology

Relations

• Refers: ASTM D3585-24 - Standard Specification for ASTM Reference Fluid for Coolant Tests
• Effective Date: 01-Mar-2024
• Refers: ASTM D3585-08(2020) - Standard Specification for ASTM Reference Fluid for Coolant Tests
• Effective Date: 01-Jan-2020
• Refers: ASTM E1177-19 - Standard Specification for Engine Coolant Grade Glycol
• 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 E1177-14 - Standard Specification for Engine Coolant Grade Glycol
• Effective Date: 01-Nov-2014
• Refers: ASTM E1177-09(2014) - Standard Specification for Engine Coolant Grade Glycol
• Effective Date: 01-Feb-2014
• Refers: ASTM D3585-08(2013) - Standard Specification for ASTM Reference Fluid for Coolant Tests
• Effective Date: 01-May-2013
• Refers: ASTM D6471-10 - Standard Specification for Recycled Prediluted Aqueous Glycol Base Engine Coolant (50 Volume % Minimum) for Automobile and Light-Duty Service (Withdrawn 2019)
• Effective Date: 01-Apr-2010
• Refers: ASTM D4985-10 - Standard Specification for Low Silicate Ethylene Glycol Base Engine Coolant for Heavy Duty Engines Requiring a Pre-Charge of Supplemental Coolant Additive (SCA)
• Effective Date: 01-Apr-2010
• Refers: ASTM D3306-10 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 01-Apr-2010
• Refers: ASTM D6472-10 - Standard Specification for Recycled Glycol Base Engine Coolant Concentrate for Automobile and Light-Duty Service (Withdrawn 2019)
• Effective Date: 01-Apr-2010
• Refers: ASTM E1177-09 - Standard Specification for Engine Coolant Grade Ethylene Glycol
• Effective Date: 01-Nov-2009
• Refers: ASTM D3306-09 - Standard Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• Effective Date: 01-Sep-2009
• Refers: ASTM D4985-09 - Standard Specification for Low Silicate Ethylene Glycol Base Engine Coolant for Heavy Duty Engines Requiring a Pre-Charge of Supplemental Coolant Additive (SCA)
• Effective Date: 01-Mar-2009
• Refers: ASTM D3585-08 - Standard Specification for ASTM Reference Fluid for Coolant Tests
• Effective Date: 01-Oct-2008

Overview

ASTM D4725-15(2023), Standard Terminology for Engine Coolants and Related Fluids, establishes a comprehensive set of terms and definitions relevant to engine coolants and related fluids. Developed by ASTM International, this standard serves as a crucial reference for professionals preparing specifications, test methods, or any technical documentation involving engine coolants. By providing uniform terminology, it helps to ensure clear communication and consistency across the automotive, heavy-duty machinery, and manufacturing sectors.

The terminology outlined in ASTM D4725-15(2023) supports compliance with international standardization principles as mandated by the World Trade Organization’s Technical Barriers to Trade (TBT) Committee. While the standard addresses terminology, it also reminds users to establish safe practices and comply with applicable regulations during its application.

Key Topics

ASTM D4725-15(2023) covers a variety of important concepts, including:

• Antifreeze and Engine Coolant Concentrate: Definitions clarify differences, usage, and properties, including the role of glycols such as ethylene glycol and propylene glycol.
• Corrosion and Inhibitor Packages: Terminology explains the inhibitors used to combat corrosion, foaming, and scaling within cooling systems.
• Coolant Additives: The document defines additive packages and supplemental coolant additives (SCA), which enhance coolant performance and system longevity.
• Performance Characteristics: Key properties such as ash content, boiling point, freezing point, foaming tendencies, and relative density are clearly detailed.
• Testing and Quality Control: Terms such as engine dynamometer test, glassware corrosion test, reference test fluid, and round-robin test support laboratory and field testing of engine coolants.
• Specialized Coolants: Descriptions include extended life coolant, low-silicate coolant, multiphase coolant, non-aqueous coolant, and recycled or redistilled glycol-based coolants.

Applications

The practical value of ASTM D4725-15(2023) extends across several industries and professional roles:

• Automotive and Heavy-Duty Industries: Manufacturers, service providers, and maintenance personnel rely on these definitions to specify, select, and maintain engine coolants for vehicles, trucks, buses, agricultural machinery, and construction equipment.
• Standardization and Compliance: The standard supports organizations in developing and interpreting various ASTM test methods and specifications by ensuring the consistent use of terminology.
• Laboratory Testing: Laboratories benefit from well-defined terms for coolant testing procedures, enabling accurate evaluation of properties such as corrosion resistance, foaming, and inhibitor effectiveness.
• Procurement and Technical Communication: Clear terminology reduces misunderstandings between suppliers, purchasers, and end-users of coolant products.
• Recycling and Sustainability: As the automotive industry shifts toward sustainable practices, the terminology for recycled engine coolants and redistilled glycol enables proper identification, use, and specification of environmentally responsible products.

Related Standards

Professionals working with engine coolants may also reference related standards, including:

• ASTM D3306: Specification for Glycol Base Engine Coolant for Automobile and Light-Duty Service
• ASTM D3585: Specification for ASTM Reference Fluid for Coolant Tests
• ASTM D4985: Specification for Low Silicate Ethylene Glycol Base Engine Coolant for Heavy-Duty Engines
• ASTM D6210: Specification for Fully-Formulated Glycol Base Engine Coolant for Heavy-Duty Engines
• ASTM D6471/D6472: Specifications for Recycled Engine Coolants (Withdrawn but formerly referenced)
• ASTM E1177: Specification for Engine Coolant Grade Glycol
• ISO 22241: Diesel engines - NOx reduction agent AUS 32

Adopting ASTM D4725-15(2023) for standardized engine coolant terminology ensures technical accuracy, regulatory compliance, and effective communication throughout the engine cooling fluids industry.

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: D4725 − 15 (Reapproved 2023)
Standard Terminology for
Engine Coolants and Related Fluids
This standard is issued under the fixed designation D4725; 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 Automobile and Light-Duty Service (Withdrawn 2019)
D6472 Specification for Recycled Glycol Base Engine Cool-
1.1 This document covers terminology relating to engine
ant Concentrate for Automobile and Light-Duty Service
coolants. It is intended to provide a reference for anyone
(Withdrawn 2019)
seeking information on engine coolants, and also to provide a
E1177 Specification for Engine Coolant Grade Glycol
uniform set of definitions for use in preparing ASTM
2.2 ISO Standard:
specifications, test methods and other standard documents.
ISO 22241 Diesel engines - NOx reduction agent AUS 32
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
antifoam, n—a substance added to engine coolant concentrate,
priate safety, health, and environmental practices and deter-
corrosion inhibitor packages, or supplemental coolant addi-
mine the applicability of regulatory limitations prior to use.
tives to prevent or suppress foam.
1.3 This international standard was developed in accor-
DISCUSSION—Eliminating foam improves heat transfer.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the antifreeze, n—a term frequently used in the marketplace for
Development of International Standards, Guides and Recom- engine coolant concentrate. (See engine coolant concen-
mendations issued by the World Trade Organization Technical trate.)
Barriers to Trade (TBT) Committee.
antirust, n—an inhibitor package, solid or liquid, intended to
be diluted with water or glycol for use in an engine cooling
2. Referenced Documents
system to mitigate rust and corrosion.
2.1 ASTM Standards:
D1193 Specification for Reagent Water ash content, n—the residue from an engine coolant
concentrate, antirust, or engine coolant that remains after
D3306 Specification for Glycol Base Engine Coolant for
Automobile and Light-Duty Service evaporation, charring, and ignition at strong heat.
D3585 Specification for ASTM Reference Fluid for Coolant
boiling point, n—the temperature at which the vapor pressure
Tests
of an engine coolant reaches atmospheric pressure under
D4985 Specification for Low Silicate Ethylene Glycol Base
equilibrium boiling conditions.
Engine Coolant for Heavy Duty Engines Requiring a
Pre-Charge of Supplemental Coolant Additive (SCA)
cavitation corrosion, n—a form of localized, accelerated
D6210 Specification for Fully-Formulated Glycol Base En- corrosion characterized by deep pitting and caused by high
gine Coolant for Heavy-Duty Engines
mechanical forces resulting from coolant vapor bubble
D6471 Specification for Recycled Prediluted Aqueous Gly- collapse at the surface of the metal.
col Base Engine Coolant (50 Volume % Minimum) for
cavitation erosion corrosion, n—the mechanical removal of
protective films on metal by the formation and collapse of
This terminology is under the jurisdiction of ASTM Committee D15 on Engine
vapor bubbles in a liquid, and the abrasive action of a liquid,
Coolants and Related Fluids and is the direct responsibility of Subcommittee
which may contain suspended solids, moving at high veloc-
D15.92 on Terminology.
ity.
Current edition approved Sept. 1, 2023. Published September 2023. Originally
DISCUSSION—The mechanical removal of the protective films exposes
approved in 1987. Last previous edition approved in 2015 as D4725 – 15. DOI:
10.1520/D4725-15R23. fresh metal to corrosive attack.
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 last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4725 − 15 (2023)
coolant additive package, n—the combination of inhibitors glycol bottoms, n—the residue in the still after final distillation
added to an engine coolant to mitigate cooling system of most of the glycol and dimers, trimers and tetramers from
degradation, corrosion, scaling, and foaming, or to provide the output stream of a glycol reactor.
other desirable properties. DISCUSSION—The residue may include some glycol and dimers,
trimers and tetramers, aldehydes, acids, and various other oxidation
corrosion inhibitor package, n—the combination of inhibitors
products. It is generally acidic, with a strong, offensive odor and a dark
added to an engine coolant to mitigate cooling system color. It is regarded as unsuitable for the production of engine coolant.
corrosion.
glycol engine coolant concentrate, n—an engine coolant
concentrate in which the freeze point depressant is ethylene
corrosive water, n—a standard solution containing 100 ppm
or propylene glycol, with inhibitors to minimize foaming
each of sulfate, chloride, and bicarbonate ions introduced as
and corrosion.
the sodium salts to distilled water.
DISCUSSION—Small amounts of other glycols may be present.
diesel exhaust fluid (DEF), n—preparation of aqueous urea
heavy-duty, adj—in internal combustion engine operation,
[(NH ) CO], containing 32.5 % by weight of technically
2 2
characterized by average speeds, power output, and internal
pure urea in high-purity water with quality characteristics
temperatures that are generally close to the potential maxi-
defined by ISO 22241.
mums.
dye, n—a colorant added to an engine coolant to give it a
heavy-duty engine, n—in internal combustion engine types,
distinctive color.
one that is designed to allow operation continuously at or
engine coolant, n—a fluid used to transfer heat from an engine
close to its peak output.
to the radiator, usually containing specific amounts of
DISCUSSION—This type of engine is typically used in (a) Class 5 to 8
glycols, water, corrosion inhibitors, and a foam supressor.
over-the-road trucks and buses, (b) off-highway machinery for
DISCUSSION—Engine coolants may also contain supplemental coolant agricultural, earthmoving, construction, and mining, (c) high-output
additives. stationary engine applications, and (d) locomotive and marine applica-
tions.
engine coolant concentrate, n—a formulated liquid product
hydrometer-thermometer field tester, n—a device designed
intended to be diluted with water for use in engine cooling
to indicate the freezing point of an engine coolant by
systems.
measurement of the relative density of the coolant at a
DISCUSSION—Functionally, the product provides a lower freeze point
specific temperature.
and mitigates corrosion and foaming.
engine dynamometer test, n—a laboratory full-scale engine inhibitor, n—a chemical compound added to engine coolant to
test designed to evaluate corrosion protection and inhibitor mitigate cooling system degradation.
stability of engine coolants under simulated operational DISCUSSION—Examples of inhibitors
...