Flammable Refrigerant Applications (A2L and A3)
As the HVAC/R industry moves toward environmentally friendly alternatives to traditional high-GWP (Global Warming Potential) refrigerants, flammable refrigerants—such as hydrocarbons and low-GWP HFO blends—are becoming increasingly common. While these alternatives offer environmental advantages, they also introduce unique safety challenges. This article explores what flammable refrigerants are, relevant safety standards, associated risks, and essential guidance on safe handling.
DOwnload flammable refrigerant safety Information
Today's requirements for environmentally friendly solutions and low GWP alternatives require system designers and manufacturers to use new refrigerant solutions.
Options are offered by the flammable refrigerants class A3 and mildly flammable refrigerants class A2L, as classified by ISO 817 (Refrigerants – Designation and safety classification).
In addition to excellent efficiency values and thermodynamic properties, however, special attention must be paid to the aspect of flammability.
If you come into contact with a system containing flammable refrigerants in the field, you must observe certain safety precautions. Working with flammable refrigerants in refrigeration systems requires appropriate training and education. Never touch a system containing flammable refrigerants, for example during commissioning, repair or maintenance, unless you have the necessary knowledge and training in handling flammable refrigerants.
What are flammable refrigerants?
The international standard ISO 817 (Refrigerants – Designation and safety classification) assigns a safety classification to refrigerants based on toxicity and flammability data. The toxicity and flammability characters combine to form a refrigerant safety classification, eg, "A3" flammable refrigerants or "A2L" mildly flammable refrigerants. Common examples of flammable refrigerants include R290 (class A3), R454C, R455A, R454A and R32 (class A2L). As used herein, "flammable refrigerants" refers to any refrigerant classified as A2L or A3.
For the system designer, manufacturer and especially for the service technician on site, the correct and safe handling of flammable refrigerants is indispensable.
In the case of a direct reference to local/regional regulations and European safety standards, such as EN 378 (Refrigerating systems and heat pumps – Safety and environmental requirements), special attention must be paid to a refrigerant charge limitation where applicable and for the requirement to carry out a system risk assessment with risk mitigation.
Qualified personnel for flammable refrigerant handling
Only competent personnel as specified in EN 13313 (Refrigerating systems and heat pumps – Competence of personnel) qualified for flammable refrigerant handling is permitted to commission, initiate and maintain the compressor/refrigeration systems using flammable refrigerant; non-trained personnel, including the user, are not allowed to do so and must call on
an expert.
Personnel working on the maintenance, repair and decommissioning of the system must be adequately trained. Any work procedure affecting safety shall only be executed by qualified and trained personnel in compliance with national or other equivalent certification systems. Examples of such work procedures are:
- breaking into the refrigerating circuit
- opening sealed components
- opening a ventilated enclosure
Risks and hazard potential of flammable refrigerants
Flammable refrigerants can ignite or explode. If flammable refrigerant is released from a system, an explosive concentration can be present in the air near the system. If there is an ignition source nearby, the release of flammable refrigerant can result in a fire or explosion. While systems using flammable refrigerant are designed to mitigate the risk of
ignition by the system itself if refrigerant is released, fire and explosion can still occur.
System risk assessment and risk mitigation
A comprehensive risk assessment is essential before designing or working on systems with flammable refrigerants. Key
steps include:
Risk assessment process
- Hazard identification: identify all sources of ignition, leak points, and confined spaces.
- Consequence analysis: evaluate what could happen in the event of a leak or fire.
- Probability analysis: determine how likely these scenarios are based on design and operating conditions.
- Risk evaluation: assess whether the risk level is acceptable or requires mitigation.
Risk Mitigation Measures
- Limit refrigerant charge size: stay within safety limits outlined in standards.
- Ensure adequate ventilation: prevent accumulation of flammable gases.
- Install leak detection systems: early warning can prevent ignition.
- Use intrinsically safe equipment: electrical components should meet explosion-proof standards.
- Labeling and signage: clearly identify systems with flammable refrigerants.
Practical safety instructions for handling flammable refrigerants in the field
Do not perform any service to the system unless you are specifically trained on flammable refrigerants.
To ensure the awareness of a potentially toxic or flammable atmosphere, the area around the system shall be checked with an appropriate refrigerant detector prior and during work on a flammable system.Continue monitoring with the refrigerant detector until you are certain there is no leak. If you detect a leak and flammable refrigerant is in the immediate vicinity, immediately stop all service work, ventilate, and evacuate the area.
When opening a flammable refrigerant system, the atmosphere could be flammable or explosive. All electrical components that are a source of ignition must always be switched off during service and maintenance. Ensure that the surface temperatures of the components never exceed the limits set by the applicable safety standard, eg, EN 378-2.
Remove all the refrigerant before opening the system. Make sure to completely remove refrigerant from all components such as heat exchangers, refrigerant accumulators, etc. Flush the system and the components with inert gas before undertaking any work and before brazing.
Ensure that the leak detection equipment is suitable for all applicable refrigerants. Personnel performing work on a refrigeration system that involves exposing the pipework shall avoid using any ignition source in a way that could lead to a fire or explosion hazard. All sources of ignition shall be kept sufficiently far from the site of installation, repair, removal or disposal during the entire time when refrigerant could be released into the surrounding space. Open flames and smoking are strictly forbidden at all times.
During service make sure that:
- the area is properly ventilated;
- the materials and equipment used are suitable for use under flammable conditions;
- only non-sparking tools are used;
- antistatic gloves and clothes are used;
- build-up of electrostatic charges is avoided;
- no unshielded or naked flame is used.
Frequently asked questions
How do I know if a system uses flammable refrigerants?
One of the first steps in safely working on a system is to identify the refrigerant used in the system and whether it is flammable. There are several ways to check if a system uses flammable refrigerant.
- Check the system nameplate
The system nameplate indicates the type of refrigerant intended for use in the system. - Check for the system technical documentation
It is under the system manufacturer's responsibility to create a guideline and make it available on the system, containing information on function, handling and safety instructions. - Check for a flame symbol on the system
Systems with flammable refrigerants must be marked for flammability. Check the compressor and the entire system and look for the flammability symbol.
Are there restrictions regarding the maximum allowable refrigerant charge?
For flammable refrigerants, there are significant restrictions regarding the maximum fill quantities. Allowable charge limits depend on: refrigerant classification (A2L, A3), room size, installation type, occupancy category and applicable standard (e.g. EN378-2 or product-oriented standards (if applicable), such as IEC 60335-2-40).
For A2L higher charges are generally permitted. For A3, charge is strictly limited unless mitigation (ventilation, detection) is implemented.
Can existing A1 systems be converted to A2L or A3?
For most A1 systems, conversion to a flammable refrigerant is not possible or permitted. All system components, as well as the system safety concept, must be approved and suitable for flammable refrigerants. Key concerns for a potential conversion are: electrical components (spark risk), compressor compatibility, oil compatibility, system tightness and certification validity.
What must be considered in a safety concept for systems using flammable refrigerants, and which legislation must be complied with?
First, the safety standard according to which the existing system is to be designed must be defined. EN 378-1-4 serves as a comprehensive safety standard for refrigeration systems and heat pumps. Depending on the specific application, product-specific standards such as EN 60335-2-40 or EN 60335-2-89 may also apply.
The refrigerant classification may be verified with ISO 817:2024.
Before installing and commissioning a system, the system installer must verify that the compressor and other components of the refrigeration system are suitable and approved for use with flammable refrigerants. Furthermore, a risk assessment with subsequent steps and measures for risk mitigation must be carried out for each system. With regard to the aspect of flammability, the risk assessment mainly deals with ignition prevention, leak management, refrigerant charge and fault tolerance.
To support customers with the risk assessment, Copeland provides Manufacturer Declarations for scroll compressors, controls, valves and drives used with flammable refrigerants.
General legislation within the European Union (outside the European Union additional requirements may apply):
- Pressure Equipment Directive 2014/68/EU. All flammable refrigerants belong to the fluid group 1, which results into a stricter PED categorization, compared to non-flammable refrigerants (fluid group 2).
- Machinery Directive 2006/42/EC for overall risk assessment and safety integration.
- Low Voltage Directive 2014/35/EU regarding the electrical safety
- ATEX Directive 2014/34/EU to be considered only if a potentially explosive atmosphere is expected in normal operation. Typically ATEX is avoided through design (ventilation, charge limits, sealed components) for cost and complexity reasons.
