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Basic Knowledge on Gases

Refrigerant Gases

Typical refrigerant gases include fluorocarbons, which are chemical compounds of carbon and fluorine. They were developed mainly as refrigerant gases to be used for refrigerators and air conditioners. There are various types of fluorocarbons such as CFCs, HCFCs, and HFCs with different chemical structures and compositions.

Besides fluorocarbons, other refrigerant gases include ammonia, carbon dioxide, and propane.

■Refrigerant Gas Types and Characteristics

Type ASHRAE Number Molecular Formula Global-Warming Potential (GWP)*1 Toxicity & Flammability Class
CFC R-12 CCl2F2 10,900 A1
R-11 CCl3F 4,750 A1
R-502 HCFC-22/CFC-115 4,520 A1
HCFC R-22 CHClF2 1,810 A1
R-123 CHCl2CF3 77 B1
HFC R-410a HFC-32/125 2,090 A1
R-407c HFC-32/125/134a 1,770 A1
R-134a CH2FCF3 1,430 A1
R-32 CH2F2 675 A2L
R-454b HFC-32/HFO-1234yf 466 A2L
R-152a CH3CHF2 124 A2
HFO R-1234yf CH2=CFCF3 1 A2L
Natural Refrigerants including Hydrocarbons R-290 C3H8(Propane) 10 A3
R-600a CH(CH3)3 (Isobutane) 4 A3
R-1270 C3H6(Propylene) 3 A3
R-744 CO2(Carbon dioxide) 1 A1
R-717 NH3 (Ammonia) <1 B1

*1 Source: The IPCC’s Fifth Assessment Report (AR5) (2014)

【ASHRAE Number】

The ASHRAE number is a number that indicates the type of refrigerant and is defined by ISO817 (International Organization for Standardization) as follows.

R Initial letter of Refrigerant
Thousands digit The number of double bonds in the unsaturated hydrocarbon molecule
Hundreds digit The number of carbon atoms minus one
Tens digit The number of hydrogen atoms plus one
Units digit The number of fluorine atoms per molecule
Suffix Indication of isomer or mixed refrigerant with different percentages of each refrigerant

【Global Warming Potential】

Global Warming Potential (GWP) is the metric of relative values used to compare the global warming impact of greenhouse gases with the reference gas. Carbon dioxide (CO2) was chosen as this reference gas and its GWP is set equal to one (1.0).

【Toxicity & Flammability Class Table】

Toxicity & Flammability Class Table
Reference: ISO 817 Refrigerants – Designation and safety classification

■ Impact of greenhouse gases on the global environment and international regulatory progress

CFCs and HCFCs used in the past had caused ozone depletion problems. CFCs and halon were banned in developed countries in 1996 due to their high impact on the ozone layer. HCFCs, which have a relatively small impact on the ozone layer, were also scheduled to be phased out by 2020, with some exceptions. HFC refrigerant gases that are currently in widespread use as alternatives of CFCs and HCFCs are non-flammable refrigerants (A1). But they have been found to be greenhouse gases that cause global warming. Subsequently, the switch to lower flammable refrigerant gases (A2L) such as HFCs with a lower GWP or HFOs has been promoted. In recent years, the use of HC refrigerants (A3) and natural refrigerants, which have even lower GWP, is being considered.

■Progress in Japan


In Japan, the Act on the Protection of the Ozone Layer through the Control of Specified Substances and Other Measures was enacted in 1988 to achieve the reduction of the production and consumption of CFCs and HCFCs based on the Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol on Substances that Deplete the Ozone Layer. As a result, 15 types of CFCs and HCFCs were completely phased out by 1996.

In addition, the Fluorocarbons Recovery and Destruction Law, the Home Appliance Recycling Law, and other related laws were enacted in 2001 in order to recover and destroy CFCs & HCFCs that had been used up, requiring the recovery and destruction of CFCs & HCFCs at the time of disposal of products containing fluorocarbons.

In light of changes in the circumstances relating to fluorocarbons, such as technological progress and global regulatory trends, the Law Concerning the Recovery and Destruction of Fluorocarbons was amended to the Act on Rational Use and Proper Management of Fluorocarbons in 2013 in order to address the issues of rapid increase in the use of HFC A1 refrigerants, which are greenhouse gases that cause global warming, slow refrigerant recovery rates, and refrigerant gas leaks during operation of HVAC equipment. The new law requires measures to be taken throughout the entire lifecycle of fluorocarbons from their production to disposal.

Following the revision of the Montreal Protocol in 2016 (Kigali Amendment), the Act on the Protection of the Ozone Layer Through the Control of Specified Substances and Other Measures was revised in Japan in 2018 to implement regulations of the production and import of A1 HFCs, which are alternatives to CFCs and HCFCs, which requires reduction of the limits of production and consumption of A1 HFCs in the country to 85% of the base level, which is the average of actual results from 2011 to 2013, by 2036 through step by step reduction of these limits.

【Trends in Associated Industries】

Under these circumstances, there is a growing trend in Japan to shift to lower flammability refrigerant gases (A2Ls), which have a lower GWP than other HFCs (A1).

The refrigerant used in residential air conditioners (RACs) has largely switched from R-410 to R-32 as of 2017.

The shift of refrigerant for commercial air conditioners (PAC: Packaged Air Conditioners) to R-32 has also been progressing. But there is little progress in shifting of refrigerant for multiple split air conditioners (VRF: Variable Refrigerant Flow) to A2L refrigerants, which will be a major issue in the future. The use of HC refrigerant gas (A3) and natural refrigerant (CO2), which have lower GWP, is also increasing for freezer/ refrigerator showcases and condensing units.

The percentage of residential air conditioners using A2L refrigerants is almost 100% in Japan. But the global switchover to A2L refrigerants is just beginning.

In 2016, the Japan Refrigeration and Air Conditioning Industry Association (JRAIA) established the technical standard entitled; [JRA4068: 2016_Requirements of refrigerant leak detector and alarm for air conditioning and refrigeration equipment] to ensure safe operation of refrigeration and air conditioning equipment using A2L refrigerant, which increases the need for gas sensors for refrigerant gas detection.