Considerations and methodologies for the safe use of flammable refrigerants for air conditioning.

Today air conditioning product and application designers, as a result of climate change contribution concerns from high global warming potential (GWP) refrigerants, are being asked to consider lower GWP refrigerants with various degrees of flammability. The HVACR industry has been actively investigating the safety of flammable refrigerants by determining their risks, potential occurrences and severity of events. Natural refrigerants, like hydrocarbons, have been investigated and seen expanded use when
safety, efficiency, and reliability can be delivered to meet the customer needs. Today R410A is used to cover most air conditioning applications. Market fragmentation by refrigerant type may result to meet the regulatory demands on high GWP refrigerants. This paper will give an overview of the selection challenges faced by air conditioning product designers when considering the varying flammability characteristics of various refrigerants. It will give a methodology to determine the refrigerant charge and resulting cooling load for hydrocarbons, and finally a process for how to design for flammability safety depending on the application. Product standards, like UL484 and UL60335- 2-40, are continually being update to include the use of flammable refrigerants and will be reviewed along with others standards for the use hydrocarbons.