Various types of refrigerant gases are used in air conditioners and other HVAC (Heating, Ventilation and Air Conditioning) equipment. Some environmentally friendly natural refrigerants are highly flammable, and in the event of are refrigerant gas leak, they can lead to serious accidents such as fires or explosions.To mitigate these risks, HVAC equipment using lower flammability (A2L) refrigerants above a certain charging volume must be equipped with gas sensors for leak detection.

What is Refrigerant Gas Used in Air Conditioners?

In air conditioning systems that regulate indoor temperatures and refrigeration/freezing systems that cool their own interiors, a crucial component is the "refrigerant," which plays the essential role of transferring heat from one area to another.
Refrigerant gas circulates through two pipes connecting the indoor and outdoor units. During cooling, the refrigerant transfers heat from the room to the outside, while during heating, it transfers heat from the outside to the room.

Mechanism of Cooling

1.  The indoor unit draws in warm air from the room, transferring its heat to the refrigerant through the evaporator.
2.  The refrigerant gas, now carrying the absorbed heat, is sent to the outdoor unit, where it is compressed to a high temperature and high pressure.
3. The high-temperature refrigerant releases heat through the outdoor unit's condenser, and the heat is expelled outside by the fan.
4. The refrigerant then cools down as it condenses into a liquid.
5. The cooled liquid refrigerant returns to the indoor unit, where it evaporates to absorb heat, cooling the air and releasing cool air into the room.

Mechanism of Refrigeration

Fluorocarbon, commonly used as a refrigerant gas, is a gas at room temperature but becomes a liquid when compressed in a compressor. When the pressure is reduced through an expansion valve, it returns to its gaseous state. The heat of vaporization released during this transition from liquid to gas cools the surrounding air.

Toxicity and Flammability of Refrigerant Gas

Types of Major Refrigerant Gases and Their Environmental Impact

Fluorocarbons (compounds of carbon and fluorine) were developed for use in refrigerators and air conditioners and are typical refrigerant gases.The toxicity and flammability of "fluorocarbons" vary depending on the type. According to international refrigerant safety standards, toxicity is classified into two levels (A: Non-toxic; B: Toxic), while flammability is divided into four classes (Class 1: Non-flammable; Class 2L: lower flammability; Class 2: Flammable; Class 3: Higher flammable).

Environmental Impact of Refrigerant Gas

There are various types of Freon with different chemical structures and compositions. Among them, CFCs (chlorofluorocarbons), a type of specified Freon previously used as refrigerants in air conditioners, were found to cause ozone layer depletion. Consequently, their production and consumption were banned in developed countries by 1996 and in Japan by 2005.

HCFCs (hydrochlorofluorocarbons), considered relatively harmless, were also identified as greenhouse gases contributing to global warming. Under the "Montreal Protocol," an international treaty that identifies types of Fluorocarbon gases and establishes global regulations, HCFCs were virtually phased out by 2020.

Subsequently, the transition to alternative Fluorocarbon gases with lower GWP (Global Warming Potential), such as HFCs (hydrofluorocarbons) and HFOs (hydrofluoroolefins), which are lower flammability (A2L) refrigerants, has been promoted. However, while these refrigerants do not deplete the ozone layer, it has become clear that they are greenhouse gases contributing to global warming.

As a result, in recent years, there has been a growing shift toward adopting "natural refrigerants," which have an even lower GWP and differ from conventional synthetic Fluorocarbon gases, posing less risk of ozone layer depletion and contributing less to global warming.

Natural refrigerants are made from substances that already exist in nature, such as ammonia (NH₃), carbon dioxide (CO₂), water (H₂O), air, and hydrocarbons (HC). For this reason, they have the advantage of having a significantly smaller environmental impact.

The Role of Gas Sensors in Detecting Refrigerant Gas Leaks

The refrigerant gas HFC (R-32), commonly used in air conditioning systems today, has a relatively low GWP but is lower flammability (A2L) refrigerants, meaning that there is a potential risk of ignition in case of gas leaks.

In addition, Natural refrigerants are being increasingly introduced for their low impact on global warming, but some of them are highly flammable (A3). For this reason, there is a need for gas sensors to detect refrigerant leaks in order to reduce the risk of fire.

Installation Locations of Air Conditioners and Their Required Specifications

The required specifications for gas sensors vary depending on the HVAC equipment in which they are used. Therefore, a wide product lineup is required to meet various conditions, including high-temperature resistance, waterproofing, dustproofing, and UV resistance.

FIGARO's Gas Sensor Modules for Refrigerant Gas Detection

FIGARO's high-sensitivity gas sensors for refrigerant gases contribute to reducing the risk of accidents by quickly detecting refrigerant gas leaks.

Gas Sensor Modules for Refrigerant Gas Detection: FCM Series

The FCM2630 series is a module equipped with high-sensitivity gas sensors capable of detecting various refrigerant gases. It is pre-calibrated for alarm points for lower flammability refrigerants (R-32). Due to its compact size, low cost and long life, it is ideal for detecting leaks of lower flammability refrigerants in HVAC equipment for household and commercial use.

Product Lineup