This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS 75.100
CCS E 34
National Standard of the People's Republic of China
GB 23971-2025
Replaces GB 23971-2009
Organic heat transfer fluids
有机热载体
(English)
Issue date: 2025-10-05 Implementation date: 2026-11-01
Issued by the State Administration for Market Regulation
the Standardization Administration of the People's Republic of China
Warning — This document pertains to products which may be dangerous if adequate precautions are not taken during production, storage, transportation, and use. This document does not purport to address all safety problems associated with the product. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This document specifies the classification and marking, requirements and test methods, rules of inspection, marking, packaging, transport, storage, and safety of unused mineral oil-based and synthetic organic heat transfer fluids.
This document is applicable to various types of organic heat transfer fluids used in indirect heat transfer systems.
This document is not applicable to fluids intended for direct use in heating or cooling oxidizing chemicals.
This document is not applicable to organic heat transfer fluids produced from reprocessed oils.
Note: Products classified as L-QA according to GB/T 7631.12 are not suitable for use in organic heat transfer fluid boilers. This document does not apply to products classified as L-QA in GB/T 7631.12.
2 Normative references
The contents of the following documents constitute the indispensable provisions of this document through normative reference in the text. For dated references, only the edition corresponding to the date applies. For undated references, the latest edition (including any amendments) applies.
· GB/T 259 Petroleum products—Determination of water-soluble acids and alkalis
· GB/T 261 Determination of flash point—Pensky-Martens closed cup method
· GB/T 265 Petroleum products—Determination of kinematic viscosity and calculation of dynamic viscosity
· GB/T 268 Petroleum products—Determination of carbon residue—Conradson method
· GB/T 508 Petroleum products—Determination of ash
· GB/T 1884 Crude petroleum and liquid petroleum products—Laboratory determination of density—Hydrometer method
· GB/T 1885 Petroleum measurement tables
· GB/T 3078 Cold-drawn steel bars of quality structural steel
· GB/T 3535 Petroleum products—Determination of pour point
· GB/T 3536 Petroleum products—Determination of flash and fire points—Cleveland open cup method
· GB/T 4756 Petroleum liquids—Manual sampling
· GB/T 4945 Petroleum products and lubricants—Determination of acid and base number—Color-indicator titration method
· GB/T 5096 Petroleum products—Corrosiveness to copper—Copper strip test
· GB/T 6536 Petroleum products—Determination of distillation characteristics at atmospheric pressure
· GB/T 7304 Petroleum products—Determination of acid number—Potentiometric titration method
· GB/T 7534 Volatile organic liquids for industrial use—Determination of boiling range
· GB/T 7631.12 Lubricants, industrial oils and related products (Class L)—Classification—Part 12: Group Q (Heat transfer fluids)
· GB/T 11133 Petroleum products, lubricants, and additives—Determination of water—Coulometric Karl Fischer titration method
· GB/T 11140 Petroleum products—Determination of sulfur content—Wavelength-dispersive X-ray fluorescence spectrometry
· GB/T 16483 Safety data sheet for chemical products—Content and order of sections
· GB/T 17040 Determination of sulfur in petroleum and petroleum products—Energy-dispersive X-ray fluorescence spectrometry
· GB/T 17144 Petroleum products—Determination of carbon residue—Micro method
· GB/T 21860 Liquid chemicals—Test method for autoignition temperature
· GB/T 23800 Determination of thermal stability for organic heat transfer fluids
· NB/SH/T 0164 Petroleum and related products—Rules for packaging, storage, transportation, and delivery acceptance
· NB/SH/T 0558 Petroleum distillates—Determination of boiling range distribution—Gas chromatography method
· NB/SH/T 0870 Petroleum products—Determination of dynamic viscosity and density and calculation of kinematic viscosity—Stabinger viscometer method
· NB/SH/T 0956 Transparent and opaque liquids—Determination of kinematic viscosity—Automated reverse-flow viscometer method
· SH/T 0246 Determination of water content in light petroleum products—Coulometric method
· SH/T 0604 Crude petroleum and petroleum products—Determination of density—Oscillating U-tube method
· SH/T 0689 Determination of total sulfur content in light hydrocarbons, motor fuels and oils by ultraviolet fluorescence method
· TSG 11 Regulation on Safety Technology for Boiler
3 Terms and Definitions
The following terms and definitions apply to this document.
3.1
organic heat transfer fluids
A general term for organic substances used as heat transfer media.
Note 1: Organic heat transfer fluids include all organic media used for indirect heat transfer purposes, such as heat transfer fluids, thermal oils, organic heat transfer media, and heat carriers.
Note 2: They can be classified as synthetic organic heat transfer fluids and mineral organic heat transfer fluids based on chemical composition; and as vapour phase organic heat transfer fluids and liquid phase organic heat transfer fluids based on boiling range.
3.2
unused organic heat transfer fluids
Organic heat transfer fluids that have not yet been put into service in a heat transfer system.
Note: This excludes products manufactured from reprocessed oils.
3.3
synthetic organic heat transfer fluids
Products manufactured by chemical synthesis processes, possessing a definite chemical structure and specific chemical name(s).
Note: Based on the maximum permitted bulk temperature, synthetic organic heat transfer fluids are classified into general synthetic types and special synthetic types with high thermal stability.
3.4
mineral organic heat transfer fluids
Products produced from petroleum-based raw materials, obtained by distillation and refining (including solvent refining and hydrotreating) processes to yield appropriate fractions.
Note: The main components are hydrocarbon mixtures.
3.5
vapour phase organic heat transfer fluids
Synthetic organic heat transfer fluids with a boiling point or azeotropic point that can be used in the vapour phase.
Note: Vapour phase organic heat transfer fluids can be used in the liquid phase under pressure and are also referred to as vapour/liquid phase organic heat transfer fluids.
3.6
liquid phase organic heat transfer fluids
Synthetic organic heat transfer fluids and mineral organic heat transfer fluids with a specific boiling range that can only be used in the liquid phase.
3.7
thermal stability
The ability of an organic heat transfer fluid to resist chemical decomposition at high temperatures.
Note: As the temperature increases, chemical reactions or molecular rearrangements occur in the organic heat transfer fluid. The resulting gaseous decomposition products, components with low boiling point, components with high boiling point, and nonvolatile decomposition products will affect the performance of the organic heat transfer fluid.
3.8
maximum permitted bulk temperature
The highest test temperature, determined according to the GB/T 23800 test method, at which the degradation rate of the tested organic heat transfer fluid does not exceed 10% (mass fraction).
3.9
maximum working temperature
The maximum permitted bulk temperature of the organic heat transfer fluid at the boiler outlet.
Note: Under operating conditions of the heat transfer system, the measured average bulk temperature of the organic heat transfer fluid at the boiler outlet is the working temperature.
3.10
maximum permitted film temperature
The temperature within the boundary layer of the organic heat transfer fluid in contact with the heated surface of the boiler.
Note: The maximum permitted film temperature is the highest allowable temperature for the organic heat transfer fluid within the boundary layer. This is the temperature that must not be exceeded by the organic heat transfer fluid at any point within the heat transfer system.
3.11
closed heating system
An organic heat transfer fluid heat transfer system where the expansion tank is isolated from the atmosphere.
Note: Closed systems are typically isolated from the atmosphere using an inert gas blanket or a cold oil seal.
3.12
open heating system
An organic heat transfer fluid heat transfer system where the expansion tank is vented to the atmosphere.
3.13
gaseous decomposition products
Substances determined by the gravimetric method in the thermal stability test according to GB/T 23800, which have a boiling point at atmospheric pressure below room temperature after the heating test.
Note: Examples include hydrogen and methane.
3.14
components with low boiling point
Substances in the heated test portion determined by simulated distillation in the thermal stability test according to GB/T 23800, which have a boiling range below the initial boiling point of the unused organic heat transfer fluid.
3.15
components with high boiling point
Substances in the heated test portion determined by simulated distillation in the thermal stability test according to GB/T 23800, which have a boiling range above the final boiling point of the unused organic heat transfer fluid.
3.16
nonvolatile decomposition products
Substances in the heated test portion that cannot be separated by simulated distillation in the thermal stability test according to GB/T 23800.
Note: These are residues quantitatively determined in the bulb tube distillator under specified conditions.
4 Classification and Marking
4.1 Product Classification
Organic heat transfer fluids shall be classified into product varieties according to GB/T 7631.12. The product designation shall be determined based on the state of use, the applicable type of heat transfer system, and the maximum permitted bulk temperature. Specific classification shall be carried out according to the provisions of Table 1.
.....
5 Requirements and Test Methods
Organic heat transfer fluids are used under high-temperature conditions. To ensure the safe operation of boilers and heat transfer systems, organic heat transfer fluids shall comply with the quality and technical requirements for organic heat transfer fluids specified in TSG 11.
The technical requirements and corresponding test methods for organic heat transfer fluids shall comply with the provisions of Table 2.
Organic heat transfer fluids used for indirect heating in the production processes of food or pharmaceuticals shall, in addition to conforming to the provisions of this document, also comply with relevant national regulations concerning food and pharmaceutical production safety.
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and marking
4.1 Product classification
4.2 Product marking
5 Requirements and test methods
6 Rules of inspection
6.1 Inspection classification and items
6.2 Lot formation
6.3 Sampling
6.4 Decision rules
6.5 Reinspection rules
7 Marking, packaging, transport, storage
8 Safety
Appendix A (Normative) Determination of total chlorine content in organic heat transfer fluids — Coulometric method
A.1 Principle
A.2 Apparatus and equipment
A.3 Reagents and materials
A.4 Test preparation
A.5 Calibration
A.6 Test procedure
A.7 Calculation
A.8 Precision
Appendix B (Normative) Test method for thermal oxidation stability of organic heat transfer fluids
B.1 Principle
B.2 Apparatus and materials
B.3 Reagents
B.4 Preparation
B.5 Apparatus temperature calibration requirements
B.6 Test procedure
B.7 Calculation
B.8 Precision
B.9 Report
Appendix C (Informative) Properties of organic heat transfer fluids
C.1 Overview
C.2 Properties
C.3 Physical parameters
C.4 Safety data sheet
Standard
GB 23971-2025 Organic heat transfer fluids (English Version)
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS 75.100
CCS E 34
National Standard of the People's Republic of China
GB 23971-2025
Replaces GB 23971-2009
Organic heat transfer fluids
有机热载体
(English)
Issue date: 2025-10-05 Implementation date: 2026-11-01
Issued by the State Administration for Market Regulation
the Standardization Administration of the People's Republic of China
Warning — This document pertains to products which may be dangerous if adequate precautions are not taken during production, storage, transportation, and use. This document does not purport to address all safety problems associated with the product. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This document specifies the classification and marking, requirements and test methods, rules of inspection, marking, packaging, transport, storage, and safety of unused mineral oil-based and synthetic organic heat transfer fluids.
This document is applicable to various types of organic heat transfer fluids used in indirect heat transfer systems.
This document is not applicable to fluids intended for direct use in heating or cooling oxidizing chemicals.
This document is not applicable to organic heat transfer fluids produced from reprocessed oils.
Note: Products classified as L-QA according to GB/T 7631.12 are not suitable for use in organic heat transfer fluid boilers. This document does not apply to products classified as L-QA in GB/T 7631.12.
2 Normative references
The contents of the following documents constitute the indispensable provisions of this document through normative reference in the text. For dated references, only the edition corresponding to the date applies. For undated references, the latest edition (including any amendments) applies.
· GB/T 259 Petroleum products—Determination of water-soluble acids and alkalis
· GB/T 261 Determination of flash point—Pensky-Martens closed cup method
· GB/T 265 Petroleum products—Determination of kinematic viscosity and calculation of dynamic viscosity
· GB/T 268 Petroleum products—Determination of carbon residue—Conradson method
· GB/T 508 Petroleum products—Determination of ash
· GB/T 1884 Crude petroleum and liquid petroleum products—Laboratory determination of density—Hydrometer method
· GB/T 1885 Petroleum measurement tables
· GB/T 3078 Cold-drawn steel bars of quality structural steel
· GB/T 3535 Petroleum products—Determination of pour point
· GB/T 3536 Petroleum products—Determination of flash and fire points—Cleveland open cup method
· GB/T 4756 Petroleum liquids—Manual sampling
· GB/T 4945 Petroleum products and lubricants—Determination of acid and base number—Color-indicator titration method
· GB/T 5096 Petroleum products—Corrosiveness to copper—Copper strip test
· GB/T 6536 Petroleum products—Determination of distillation characteristics at atmospheric pressure
· GB/T 7304 Petroleum products—Determination of acid number—Potentiometric titration method
· GB/T 7534 Volatile organic liquids for industrial use—Determination of boiling range
· GB/T 7631.12 Lubricants, industrial oils and related products (Class L)—Classification—Part 12: Group Q (Heat transfer fluids)
· GB/T 11133 Petroleum products, lubricants, and additives—Determination of water—Coulometric Karl Fischer titration method
· GB/T 11140 Petroleum products—Determination of sulfur content—Wavelength-dispersive X-ray fluorescence spectrometry
· GB/T 16483 Safety data sheet for chemical products—Content and order of sections
· GB/T 17040 Determination of sulfur in petroleum and petroleum products—Energy-dispersive X-ray fluorescence spectrometry
· GB/T 17144 Petroleum products—Determination of carbon residue—Micro method
· GB/T 21860 Liquid chemicals—Test method for autoignition temperature
· GB/T 23800 Determination of thermal stability for organic heat transfer fluids
· NB/SH/T 0164 Petroleum and related products—Rules for packaging, storage, transportation, and delivery acceptance
· NB/SH/T 0558 Petroleum distillates—Determination of boiling range distribution—Gas chromatography method
· NB/SH/T 0870 Petroleum products—Determination of dynamic viscosity and density and calculation of kinematic viscosity—Stabinger viscometer method
· NB/SH/T 0956 Transparent and opaque liquids—Determination of kinematic viscosity—Automated reverse-flow viscometer method
· SH/T 0246 Determination of water content in light petroleum products—Coulometric method
· SH/T 0604 Crude petroleum and petroleum products—Determination of density—Oscillating U-tube method
· SH/T 0689 Determination of total sulfur content in light hydrocarbons, motor fuels and oils by ultraviolet fluorescence method
· TSG 11 Regulation on Safety Technology for Boiler
3 Terms and Definitions
The following terms and definitions apply to this document.
3.1
organic heat transfer fluids
A general term for organic substances used as heat transfer media.
Note 1: Organic heat transfer fluids include all organic media used for indirect heat transfer purposes, such as heat transfer fluids, thermal oils, organic heat transfer media, and heat carriers.
Note 2: They can be classified as synthetic organic heat transfer fluids and mineral organic heat transfer fluids based on chemical composition; and as vapour phase organic heat transfer fluids and liquid phase organic heat transfer fluids based on boiling range.
3.2
unused organic heat transfer fluids
Organic heat transfer fluids that have not yet been put into service in a heat transfer system.
Note: This excludes products manufactured from reprocessed oils.
3.3
synthetic organic heat transfer fluids
Products manufactured by chemical synthesis processes, possessing a definite chemical structure and specific chemical name(s).
Note: Based on the maximum permitted bulk temperature, synthetic organic heat transfer fluids are classified into general synthetic types and special synthetic types with high thermal stability.
3.4
mineral organic heat transfer fluids
Products produced from petroleum-based raw materials, obtained by distillation and refining (including solvent refining and hydrotreating) processes to yield appropriate fractions.
Note: The main components are hydrocarbon mixtures.
3.5
vapour phase organic heat transfer fluids
Synthetic organic heat transfer fluids with a boiling point or azeotropic point that can be used in the vapour phase.
Note: Vapour phase organic heat transfer fluids can be used in the liquid phase under pressure and are also referred to as vapour/liquid phase organic heat transfer fluids.
3.6
liquid phase organic heat transfer fluids
Synthetic organic heat transfer fluids and mineral organic heat transfer fluids with a specific boiling range that can only be used in the liquid phase.
3.7
thermal stability
The ability of an organic heat transfer fluid to resist chemical decomposition at high temperatures.
Note: As the temperature increases, chemical reactions or molecular rearrangements occur in the organic heat transfer fluid. The resulting gaseous decomposition products, components with low boiling point, components with high boiling point, and nonvolatile decomposition products will affect the performance of the organic heat transfer fluid.
3.8
maximum permitted bulk temperature
The highest test temperature, determined according to the GB/T 23800 test method, at which the degradation rate of the tested organic heat transfer fluid does not exceed 10% (mass fraction).
3.9
maximum working temperature
The maximum permitted bulk temperature of the organic heat transfer fluid at the boiler outlet.
Note: Under operating conditions of the heat transfer system, the measured average bulk temperature of the organic heat transfer fluid at the boiler outlet is the working temperature.
3.10
maximum permitted film temperature
The temperature within the boundary layer of the organic heat transfer fluid in contact with the heated surface of the boiler.
Note: The maximum permitted film temperature is the highest allowable temperature for the organic heat transfer fluid within the boundary layer. This is the temperature that must not be exceeded by the organic heat transfer fluid at any point within the heat transfer system.
3.11
closed heating system
An organic heat transfer fluid heat transfer system where the expansion tank is isolated from the atmosphere.
Note: Closed systems are typically isolated from the atmosphere using an inert gas blanket or a cold oil seal.
3.12
open heating system
An organic heat transfer fluid heat transfer system where the expansion tank is vented to the atmosphere.
3.13
gaseous decomposition products
Substances determined by the gravimetric method in the thermal stability test according to GB/T 23800, which have a boiling point at atmospheric pressure below room temperature after the heating test.
Note: Examples include hydrogen and methane.
3.14
components with low boiling point
Substances in the heated test portion determined by simulated distillation in the thermal stability test according to GB/T 23800, which have a boiling range below the initial boiling point of the unused organic heat transfer fluid.
3.15
components with high boiling point
Substances in the heated test portion determined by simulated distillation in the thermal stability test according to GB/T 23800, which have a boiling range above the final boiling point of the unused organic heat transfer fluid.
3.16
nonvolatile decomposition products
Substances in the heated test portion that cannot be separated by simulated distillation in the thermal stability test according to GB/T 23800.
Note: These are residues quantitatively determined in the bulb tube distillator under specified conditions.
4 Classification and Marking
4.1 Product Classification
Organic heat transfer fluids shall be classified into product varieties according to GB/T 7631.12. The product designation shall be determined based on the state of use, the applicable type of heat transfer system, and the maximum permitted bulk temperature. Specific classification shall be carried out according to the provisions of Table 1.
.....
5 Requirements and Test Methods
Organic heat transfer fluids are used under high-temperature conditions. To ensure the safe operation of boilers and heat transfer systems, organic heat transfer fluids shall comply with the quality and technical requirements for organic heat transfer fluids specified in TSG 11.
The technical requirements and corresponding test methods for organic heat transfer fluids shall comply with the provisions of Table 2.
Organic heat transfer fluids used for indirect heating in the production processes of food or pharmaceuticals shall, in addition to conforming to the provisions of this document, also comply with relevant national regulations concerning food and pharmaceutical production safety.
Contents of GB 23971-2025
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and marking
4.1 Product classification
4.2 Product marking
5 Requirements and test methods
6 Rules of inspection
6.1 Inspection classification and items
6.2 Lot formation
6.3 Sampling
6.4 Decision rules
6.5 Reinspection rules
7 Marking, packaging, transport, storage
8 Safety
Appendix A (Normative) Determination of total chlorine content in organic heat transfer fluids — Coulometric method
A.1 Principle
A.2 Apparatus and equipment
A.3 Reagents and materials
A.4 Test preparation
A.5 Calibration
A.6 Test procedure
A.7 Calculation
A.8 Precision
Appendix B (Normative) Test method for thermal oxidation stability of organic heat transfer fluids
B.1 Principle
B.2 Apparatus and materials
B.3 Reagents
B.4 Preparation
B.5 Apparatus temperature calibration requirements
B.6 Test procedure
B.7 Calculation
B.8 Precision
B.9 Report
Appendix C (Informative) Properties of organic heat transfer fluids
C.1 Overview
C.2 Properties
C.3 Physical parameters
C.4 Safety data sheet
