About Flammable Refrigerant
What is refrigerant?
Refrigerants generally refer to substances which produce cooling effect through their physical properties. They are commonly used in air-conditioning and refrigeration equipment, household air-conditioners, refrigerators and dehumidifiers.
Development of refrigerants
Among the air-conditioning and refrigeration equipment in Hong Kong’s market today, most adopt hydrofluorocarbons (HFCs) as refrigerants, which are neither flammable nor ozone depleting and are compliant with the existing relevant safety and environmental statutory requirements. However, HFCs have high global warming potential (GWP) and their emission into the atmosphere will negatively impact global warming. In October 2016, during the 28th Meeting of the Parties to the Montreal Protocol held in Kigali, Rwanda, the Kigali Amendment to the Montreal Protocol was adopted to phase down the production and consumption of hydrofluorocarbons (HFCs). This Amendment was subsequently entered into force on 1 January 2019. Given the above development, there has been an increasingly widespread use of low GWP refrigerants in air-conditioning and refrigeration systems around the world in recent years. However, some of them are flammable in nature.
In Hong Kong, a kind of mildly flammable refrigerant, which is difluoromethane (R32), is used in household air-conditioners. R32’s GWP is 675, which is lower than that of the conventional HFC refrigerants (for example, GWPs of R134a and R410A are 1430 and 2090 respectively). Nevertheless, R32 is one of the eighteen HFCs to be phased down under the Kigali Amendment.
What is flammable refrigerant?
According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers Standard 34 (ASHRAE 34) and International Organization for Standardization 817 (ISO 817), refrigerants are classified based on their safety levels. The safety classification shall consist of two alphanumeric characters with a third character L designating low burning velocity. The capital letter indicates the toxicity, whereas the Arabic numeral denotes the flammability.
| Flammability | Safety Group | |
|---|---|---|
| Higher flammability | A3 | B3 |
| Flammable | A2 | B2 |
| Lower flammability | A2L | B2L |
| No flame propagation | A1 | B1 |
| Lower Toxicity | Higher Toxicity | |
Types of refrigerant used in Hong Kong
Some common types of refrigerants used in household appliances and commercial equipment in Hong Kong are listed below for reference:-
| Air conditioning and refrigeration system | Non-flammable Refrigerant | Flammable Refrigerant |
|---|---|---|
| Household Air-conditioner | R410A | R32 (mildly flammable) |
| Household Refrigerator | R134a | R600a (highly flammable) |
| Commercial Air-conditioning System | R134a R410A R407C R513A R1233zd | - |
| Standalone Commercial Refrigerator | R134a | R290 (highly flammable) R600a (highly flammable) |
Refrigerants, Flammable & Toxic
There has never been a more complicated and confusing time surrounding refrigerants than what we are in right now.
We are seeing flammable HC (hydrocarbon) refrigerants with increasing regularity, and EPA rules that just changed appear to be changing again.
With all this tumultuous change, it's important to know what to look for in refrigerants and what makes a good refrigerant in the first place.
A good refrigerant:
- Has high latent heat of vaporization (it moves a lot of heat per lb when it boils)
- Boils and condenses at temperatures we can easily manipulate with compression (the pressures work)
- Mixes with the oil appropriately so that the oil can do the job of lubricating the compressor and return
- Doesn't blow stuff up or catch on fire
- Doesn't poison people
- Doesn't hurt the environment
That pretty much sums it up.
Because we have seen increased environmental regulations over the last 25 years, there has been a push to find good refrigerants, even if it means going into the flammable and toxic spectrum.
Thankfully, refrigerants are well marked. So long as we pay attention and follow best practices, there shouldn't be any issues.
The markings are pretty simple:
- Class A refrigerants have low toxicity
- Class B refrigerants have high toxicity
- Class 1 refrigerants have low flammability
- Class 2L refrigerants are only “mildly” flammable
- Class 2 refrigerants are low flammability but higher than 2L
- Class 3 refrigerants are highly flammable
The most common toxic refrigerant is ammonia, and you would generally only find it in old appliances or large industrial applications.
Propane (R290) is a flammable refrigerant and is becoming quite popular in small self-contained refrigeration units like vending machines and reach-in coolers. These propane units will be very clearly marked and should be handled with extreme caution, especially when electrical sparks or open flames are or could be present.
True Refrigeration has some good training materials on R290, such as this video.
As refrigerants become more toxic and flammable, it becomes more important to evacuate the system properly to get oxygen out of the system and make sure the systems are free of leaks.
In 2020, the American Innovation and Manufacturing (AIM) Act was enacted into law, which authorizes a 15-year phasedown of hydrofluorocarbons (HFCs) across of a variety of applications—including HVAC.
Come 2025, the Environmental Protection Agency (EPA) will set a 750 global warming potential (GWP) limit for air conditioning. This means that R-410A, with a GWP of 2,088, will no longer be able to be used in new equipment.
So, what will it be replaced with?
The most common low GWP alternatives are classified by ASHRAE as mildly flammable, or A2L. Due to their mildly flammable characteristics, A2L refrigerants will require updates to standards and building codes to allow for their safe installation.
But the good news is most contractors’ day-to-day work won’t change. It will be “business as usual,” says Jose De La Portilla, Senior Manager of Education and Training at Rheem.
Here’s what you need to know about the upcoming 2025 HVAC refrigerant change and A2Ls to start preparing.
In this training class, Bryan Orr from HVAC School provides key facts and information for HVAC technicians about the transition to mildly flammable A2L refrigerants like R-32 and R-454B being adopted for residential and light commercial systems. He covers the reasons behind the phase-down of higher global warming refrigerants like R-410A, the differences between A2L refrigerants and propane, similarities and differences compared to R-410A, changes to equipment and components, best practices for handling mildly flammable refrigerants safely, evacuation procedures, leak testing, and more. This is a must-watch for any residential HVAC tech getting ready to work on new A2L systems in the coming years. Bryan dispels misinformation and fear-mongering around these new refrigerants while still emphasizing the proper precautions that should be taken.
What are A2L Refrigerants?
“A2L refrigerants can be a single refrigerant or a blend of multiple refrigerants in specifics amounts,” De La Portilla says.
A2Ls have a lower flammability rating compared to A3 refrigerants such as hydrocarbons, propane, and isobutane. They also have a lower toxicity rating than B series refrigerants such as ammonia. In fact, A2L refrigerants are considered the second safest class of refrigerants.
A2Ls and HVAC
A2Ls have been in use for years in small HVAC appliances such as window units or packaged terminal air conditioners (PTAC). They have also been used overseas in residential and commercial HVAC equipment.
Moving forward, there will be two primary refrigerants that be used for comfort cooling: R-454B and R-32.
“Rheem has chosen R-454B are our primary refrigerant,” De La Portilla says. “However, there may be some products, such as mini-splits, that use R-32.”
A2L Myths and Facts
Myth 1: A2L refrigerants are likely to cause a fire.
Despite their mildly flammable classification, A2L refrigerants are extremely hard to ignite. The amount of an A2L needed in the air to ignite is much larger and takes a tremendous amount of energy compared to an A3 refrigerant. Extensive testing with A2Ls and numerous heat sources—including cigarettes, lighters, power drills, and various household appliances—has been done, and no heat source produced ignition.
In fact, compared to propane and natural gas, A2L refrigerants have much lower flammability risk because of:
- Higher Lower Flammability Limit (LFL): A2Ls much reach a higher concentration to become flammable.
- Higher Minimum Ignition Energy (MIE): A2Ls are harder to ignite.
- Lower Heat of combustion (HOC): There is less energy released if burned.
- Lower Burning Velocity (VC): If lit, the flame spreads slowly.
In the unlikely event that an ignition event does take place, “A2Ls have a very lazy flame, and as soon as the heat source is removed, the flame extinguishes itself,” De La Portilla says.
Myth 2: If a leak occurs, I need to remove the entire charge, fix the leak and start again.
R-454B is classified as a zoetrope. It does have a glide (1.4°F), but it is so low that it can be topped off without the need to recover the entire refrigerant charge.
Myth 3: I have to take another EPA exam.
A2Ls might be regulated by the EPA, but there is not additional certification needed to work with A2Ls. Contractors and technicians who already hold an EPA Section 608 certification will be grandfathered in and do not need to take an additional exam.
Myth 4: I will need to buy all new tools.
Many tools used daily will not need to change. Some of your current tools may even already be A2L-approved. Check with your tool manufacturer to see what is approved.
Myth 5: I can add A2L refrigerants to a system designed for A1 refrigerants.
It is extremely important that A2L refrigerants are only used in equipment designed for A2L refrigerants. They cannot be used in existing A1 systems under any circumstance.
At Rheem, the following components have been redesigned for use with A2L refrigerants:
- Compressor
- Expansion valve
- Electrical components
- Refrigerant charge size
Rheem is actively involved in discussions on regulatory issues and will be sharing more information on A2Ls as 2025 gets closer. In the meantime, you can stay in the know with the latest in the industry today at Rheem.com/HVACKnowZone.
How to Evacuate an AC system, Full Vacuum Procedurer32 is flammable ???
When designed and installed properly, R32 air conditioners are generally considered safe for use in residential and commercial settings. Manufacturers of air conditioning systems that use R32 typically incorporate safety features and design considerations to mitigate the risks associated with its flammability.
Here are some factors that contribute to the safety of using R32 in air conditioners:
- Proper Design: R32 air conditioners are designed to contain the refrigerant securely within the system. The design includes features such as pressure relief valves and flame retardant materials to enhance safety.
- Installation by Professionals: It is crucial that R32 air conditioners are installed by certified professionals who are trained to handle flammable refrigerants safely. Proper installation reduces the risk of leaks and ensures the system operates as intended.
- Regular Maintenance: Routine maintenance and inspections of the air conditioning system are essential to ensure that it is functioning correctly and there are no leaks that could pose a safety hazard.
- Ventilation: Adequate ventilation in the room where the air conditioner is installed can help dissipate any leaked gas and reduce the risk of ignition.
- Safety Standards: Manufacturers adhere to safety standards and regulations when designing R32 air conditioners to ensure they meet safety requirements.