Similarly with R410A, R32 is also Hydroflurocarbon(HFC) refrigerant, a man-made gas. Besides that R32 is better alternatives of R410A in reducing greenhouse gases, another thing that catches the consumers’ eye is the difference of flammability between this 2 refrigerant.
R32 is label as “Flammable” in Refrigerant Safety Data Sheet.
Most of MSDS only recognize refrigerant in 2 categories – “Non-flammable” and “Flammable”, because MSDS have to be simplified to follow the Harmonised Standard in creating the safety data sheet.
Only in ISO 817:2014, the flammability is categorised into more precise 4 categories – “Non-combustible”, “Mildly flammable”, “Flammable”, and “Highly flammable”. R32 is rated as mildly flammable. There are concerns for mild flammability pose the greatest challenge to convert to lower GWP gasses.
Refrigerant Safety Classes
| Flammability | Class | Examples of Refrigerant |
| Highly flammable | A3 | R290 |
| Flammable | A2 | |
| Mildly flammable | A2L | R32 |
| Non-combustible | A1 | R410A |
To assess the risk of mildly flammable refrigerants, experts are looking in several aspects like humidity, Burning velocity (Su), Minimum ignition energy and others stated in the table below.
| Refrigerant | R410A | R32 | R290 |
| Boiling temperature, °C | -51.4 | -51.7 | -42.1 |
| Critical temperature, °C | 71.3 | 78.1 | 96.7 |
| GWP (100 Years) | 2088 | 675 | <3 |
| Burning velocity (cm/s) | – | 6.7 | 38.7 |
| LFL [vol %] | – | 13.3 | 1.8 |
| UFL [vol %] | – | 29.3 | 9.5 |
| Minimum ignition energy (mJ) | – | 15 | 0.246 |
| Toxicity | – | – | – |
R32 is not much dependent on humidity. In connection with R410A, although R410A is considered to be non-flammable, but it can become flammable under relative humidity(RH) of 50% at 60 °C too.
Actually, for R32 if the burning velocities is smaller than 10cm/s, it will not ignite if the concentration level in a room stays below the lower flammable limit (0.306kg/m³).
Singapore NEA introduces measures to coupe greenhouse gasses
From 2022 onwards, companies that carry out the installation, maintenance or decommissioning of chillers will be required to employ at least one certified chiller technician.
In summary, R32 is a refrigerant belonging to safety class A2L, certain extra precautions need to be taken in the planning and installation of air conditioning system. For your safety, action such as smoking in R32 gas air-conditioned room is not encourage.
DIN EN 378 and IEC 60335 guides must be observed in order to guarantee the safety, aircon installers must be trained by experts and get licensed to install R32 gasses aircon.
This article is not exhaustive and should not be taken as professional advice. For further knowledge of Risk Assessment of Mildly Flammable Refrigerants, can read from the report below:
https://www.jsrae.or.jp/committee/binensei/final_report_2016r1_en.pdf
To learn more about how NEA initiating to reduce greenhouse gas emissions from air-conditioning, can read from the website below: