GB/T 45816-2025Road vehicles - Refrigerant systems used in mobile air conditioning systems - Safety requirements (English PDF)

3.1 Refrigerant system

3.12 Hazard

An event that could result in harm to people or the environment.

3.13 Risk

A quantitative assessment of the probability or likelihood of a specified hazard occurring.

3.14 Time-weighted average; TWA

The average mass concentration of harmful substances in the air during a specified period of time.

3.15 Exposure

The contact of one or more biological, chemical or physical factors with the human body in time and space.

3.16 Lowest observed effect level; LOEL

The lowest concentration or amount of a substance that is likely to cause any detectable change in the morphology, function, growth, development or lifespan of the target organism.

3.17 No observed effect level; NOEL

The highest concentration or amount of a substance that does not cause any detectable change in the morphology, functional growth, development or lifespan of the target organism under specified exposure conditions.

4.1 General

4.1.1 This Document aims to minimize the hazards to personnel, vehicles, property, and the environment caused by failure of mobile air conditioning (MAC) refrigerant systems and the used refrigerants, and to ensure that the safety level of MAC refrigerant systems using other refrigerants is equivalent to that of systems using HFC-134a refrigerant. The potential hazards resulting from failure of the refrigerant system and the used refrigerant may be related to the following factors.

a) the physical and chemical properties of the refrigerant (such as pressure, toxicity, and flammability), as well as the refrigerant charge, pressure, and temperature in the refrigerant system;

b) the passenger compartment volume, air exchange rate, and refrigerant system components located within the passenger compartment;

c) elevated refrigerant concentrations in the passenger compartment or engine compartment, which could lead to direct inhalation of refrigerant or its decomposition products, potentially posing a health hazard to personnel;

d) ignition of refrigerant at sufficient concentrations in the air by an accidental open flame;

e) accidental entry of decomposition products of refrigerant leaking from the engine compartment into the passenger compartment due to ignition or thermal decomposition;

f) noise release resulting in startling, irritation, or other disturbances to the driver, potentially posing a hazard to passengers or pedestrians;

g) the quality and durability of risk-level refrigerant system components over the vehicle's lifecycle;

h) refrigerant system leaks caused by improper repairs or serious maintenance errors. The risk of the refrigerant quality and charge in the system failing to meet design requirements;

i) Vehicle accidents and failures that increase the refrigerant system risk level;

j) Increased refrigerant concentration in the passenger compartment due to increased refrigerant charge or increased pipe connections (e.g., battery cooling systems, dual evaporator systems, etc.);

k) Risks arising from increased external surface temperatures of engine components in vehicles using HFO-1234yf refrigerant in MAC systems. This risk shall be identified through a systematic risk analysis process, including a detailed analysis of the system and components, the system environment, and the intended use. Historical failure data (if available) and the severity and likelihood of each identified risk shall also be included in the risk analysis.

4.1.2 Risk assessment methods for MAC systems are described in 4.2.Risk assessment information for MAC systems using each refrigerant is described in 4.3.

4.1.3 Safety requirements for refrigerant systems are described in Clause 5; and safety requirements for refrigerant system components are described in Clause 6.

4.2 Risk assessment

Risk assessment for MAC systems is a multi-step process that requires reviewing various types of data and summarizing them to form a quantitative assessment of potential risks. The risk assessment methodology is as follows.

a) Assess refrigerant toxicity data. This data can be sourced from professionally reviewed scientific literature or newly initiated studies. For newly initiated studies, the study report must be reviewed to ensure the accuracy of the study protocol, report of results, any

Refrigerant toxicity limits are expressed as a time-weighted average (TWA) representing the toxicity limit requirement over a specified timeframe.

b) Scenarios to be assessed in the risk assessment.

1) Leakage in the passenger compartment of a MAC system, resulting in R744 exposure concentrations exceeding health limits;

NOTE. Smaller leaks (corrosion leaks) are associated with leaks during normal operation of the MAC system, while larger leaks are associated with refrigerant line ruptures caused by vehicle collisions.

2) R744 exposure concentrations exceeding health limits during vehicle maintenance;

3) Liquid or debris splashing due to a high-pressure system rupture;

4) Driver shock due to a high-pressure system rupture, resulting in an accident.

5.1 Refrigerant system

5.1.1 Refrigerant type

The refrigerant system must be charged with the specified refrigerant according to design requirements.

5.1.2 Maximum refrigerant charge

Vehicle manufacturers must specify the maximum refrigerant charge in the refrigerant system.

When specifying the maximum charge, the tolerances of the charging equipment used during manufacturing and aftersales operations must be considered.

5.1.3 Refrigerant concentration in the vehicle

5.1.3.1 Refrigerant from the evaporator may leak directly into the passenger compartment or air ducts, resulting in increased refrigerant concentration in the passenger compartment.

Refrigerant concentration is primarily affected by the amount of refrigerant leakage and the operating mode of the vehicle and air conditioning system components.

5.1.3.2 Vehicle manufacturers must consider the minimum air exchange rate requirements based on the net volume of the passenger compartment and refrigerant charge to ensure that the refrigerant concentration does not exceed the maximum level specified in 4.3.The passenger compartment volume is determined by the vehicle manufacturer during development. The passenger compartment volume may be affected by changes to the vehicle interior.

5.1.4 Special requirements for maximum charge of R744 refrigerant

For refrigerant systems using R744 refrigerant, the ratio of refrigerant charge to internal system volume of the refrigerant system shall not exceed 250 g/dm³ to ensure sufficient margin for low-pressure relief devices.

5.1.5 Refrigerant additives

Vehicle manufacturers shall ensure that the toxicity or flammability levels of their specified additives do not exceed those specified in the risk assessment.

5.2 Pressure and temperature ranges

The design requirements for the pressure and temperature ranges of MAC systems shall comply with the provisions of Appendix B.

Vehicle manufacturers may specify more stringent pressure and temperature ranges.

5.3 System layout

5.3.1 Refrigerant piping connections in the engine room

The external contours of the refrigerant system and the layout of the refrigerant piping shall not affect the vehicle's ground clearance. The refrigerant system design shall reduce the risk of collision with the ground or loose objects.

The service port shall be located to facilitate the connection of service hoses and ensure a secure and reliable connection.

Refrigerant systems using HFO-1234yf refrigerant shall be assessed for the potential risk of leaking refrigerant and refrigeration oil splashing onto hot component surfaces.

5.3.2 Refrigerant piping connections in the passenger compartment

For refrigerant systems using HFC-134a refrigerant, there are no restrictions on the layout and location of connection points, components, and refrigerant piping.

For refrigerant systems using HFO-1234yf and R744 refrigerants, at least one of the following requirements must be met.

--- Refrigerant piping and its connection points must be located outside the passenger compartment, ensuring that refrigerant cannot enter the passenger compartment;

--- Ensure that sealing requirements are met and that refrigerant leakage safety requirements are met during repair and maintenance.

NOTE. In vehicles, the evaporator is located inside the passenger compartment as part of the

HVAC system. Refrigerant piping and other components in the refrigerant system are generally located outside the passenger compartment, with some refrigerant piping integrated into the

HVAC system. Some vehicles also have a second HVAC system installed with refrigerant lines routed inside the passenger compartment.

5.4 Pressure and temperature limitations

5.4.1 System operating pressure limitations

The system design shall ensure that the system operating pressure does not exceed the maximum pressure allowed by the system design. If a pressure relief device is used, it shall be installed in a location with minimal risk.

5.4.2 Refrigerant temperature limitations

The system design shall ensure that the refrigerant temperature in the system does not exceed the maximum refrigerant temperature.

6.1 General requirements

6.1.1 Burst pressure

6.1.1.1 The ultimate burst pressure of components not subjected to fatigue stress shall be no less than twice the maximum pressure on the high-pressure and low-pressure sides of the refrigerant system as specified in Table B.1.

6.1.1.2 For refrigerant systems using R744 refrigerant, high-pressure components of the

refrigerant system (i.e., the compressor discharge side, gas cooler, and the connecting piping between these components) that may experience a decrease in tensile strength due to temperature and pressure effects shall be tested as follows.

a) The components shall be subjected to normal system operating conditions to simulate the refrigerant system conditions (e.g., temperature, pressure, pressure cycling, vibration, corrosion, etc.) under actual vehicle use;

b) After simulating normal system operating conditions, the burst pressure of each component at operating temperature shall be no less than 1.5 times the maximum pressure on the high-pressure and low-pressure sides of the refrigerant system as specified in Table B.1.

6.1.2 Materials

6.1.2.1 The materials comprising refrigerant system components shall satisfy the maximum operating temperature and pressure ranges over the vehicle's lifecycle. The effects of the vehicle's operating environment on the materials shall be assessed, including vehicle speed, mechanical loads, vibration, wear caused by particulate matter, and corrosive environments (e.g., road salt to remove snow, salt spray, or airborne substances).

6.1.2.2 For components used within the vehicle internal part or in air ducts leading to the vehicle internal part, corrosion-related failures may result in increased refrigerant concentrations in the passenger compartment and endanger occupant health. If a corrosion-induced leak occurs, the materials of refrigerant system components shall ensure that the leakage rate does not increase dramatically.

6.1.2.3 During continuous operation of a refrigerant system, the process of decreasing

refrigerant charge until it is completely depleted may cause changes in the temperature and/or pressure properties of the refrigerant. The materials of system components shall be able to withstand physical impact and chemical attack from the refrigerant and refrigeration oil.

6.1.2.4 Material selection shall assess changes in material properties caused by mechanical, chemical, and thermal shock during the production and storage processes.

6.1.2.5 For components assembled or manufactured from different materials and physically

connected to other components, if these components are stored in a humid environment, contaminated water acting as an electrolyte may cause electrochemical corrosion of the materials.

NOTE. Factors such as the surface area ratio of the anode and cathode, material type, and system operating conditions (e.g., temperature, humidity, salinity, etc.) shall affect electrochemical corrosion.

6.1.2.6 Non-metallic materials such as rubber, plastics, and elastomers shall meet the mechanical, thermodynamic, chemical, and physical requirements of the refrigerant and refrigeration oil mixture and shall not produce products that pose a fire hazard. The electrical properties of these materials related to electrochemical corrosion shall also be assessed.

6.1.2.7 The materials of refrigerant system components shall meet the requirements of GB/T

30512.

6.2 Pipeline and connections

6.2.1 General requirements

Refrigerant system pipeline and connections shall be designed to ensure that, under normal use, passengers or persons near the vehicle are not exposed to leaked high-concentration refrigerant, oil aerosols, and/or other dispersed liquids or gases.

Pipeline and connecting components shall be designed to minimize the potential for hazards caused by improper installation.

6.2.2 Sealing requirements

6.2.2.1 Refrigerant system pipeline and fittings shall meet sealing requirements during

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