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.

Safety Group
Higher flammability A3 B3
Flammable A2 A2
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:-

Non-flammable Refrigerant Flammable Refrigerant
Household Air-conditioner R410A R32 (mildly flammable)
Household Refrigerator R134a R600a (highly flammable)
Commercial Air-conditioning System R134a
Standalone Commercial Refrigerator R134a R290 (highly flammable)
R600a (highly flammable)