The U.S. Air Conditioning, Heating and Refrigeration Institute (AHRI) has set up a subcommittee to conduct a review of the safety issuesaround mildly flammable refrigerants, to complete the necessary research, and share the results with regulators and standard developers.
They are flammable, since they have flammability limits, but they are typically difficult to ignite. ASHRAE Standard 34 considers refrigerants to be designed as 2L if they
– Require more than 100 g/m3 to burn (typically 300 g/m3 Propane 38 g/m3)
– Have a heat of combustion lower than 19 000 kJ/kg (Propane : 46 300 kJ/kg)
– Have a burning velocity lower than 10 cm/s (Propane : 46 cm/s)
With the growing use of 2L refrigerants, there is a need for further research in order to provide scientific results necessary to support the safe use of these refrigerants (example of a recently granted research project).
The Flammable Refrigerants Subcommittee will determine gaps in existing flammable refrigerant research. It aims to help industry to understand the comparative risk of using 2L refrigerants with those used today.