Lethal R40 refrigerant blamed for Korean AC fires

SOUTH KOREA: The National Fire Agency, Korea’s central fire administrative agency, has blamed a series of recent air conditioner fires on illegal mixed refrigerants containing dangerous R40 (methyl chloride).

A total of 36 fires are suspected to have been caused by air conditioner refrigerants have been recorded over the past five years. In each case, trimethyl aluminium was detected inside the outdoor units where the fires occurred.

Highly flammable trimethyl aluminium, a liquid at room temperature which ignites spontaneously on contact with air, is formed when R40 reacts with aluminium in HVAC systems.

In 2011/12, blends of R40 and non-flammable R22, falsely labelled and sold as R134a, were responsible for a number of explosions and deaths around the world. The issue was a particular problem in the refrigerated container industry and led to the grounding of thousands of reefers. 

In December last year, the Canadian government revealed that the potentially lethal R40 had been found in cylinders labelled as R32. 

According to the latest case in Korea, the problem is increasing. The number of fires attributed to the use of refrigerant containing R40 increased from one in 2022, two in 2023, six in 2024 and 13 last year. The number of cases had risen to 14 by July this year. 

In July, a fire investigator at a house fire suffered second-degree burns on both hands due to a spark generated at the refrigerant inlet of an outdoor unit. The previous month, a man in his 70s charging refrigerant into an air conditioning system was severely injured in an explosion. 

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Fake R410A refrigerant mixed R40 with R32 – 9 December 2025
CANADA: The Canadian government has revealed that the recently discovered fake refrigerant was a mixture of R32 and the potentially lethal methyl chloride (R40). Read more…