Overview of Hazards Presented By the Renewed Focus on Use of Flammable Refrigerants

In recent years, driven by demand for low ozone depletion potential (ODP) and global warming potential (GWP) refrigerants, an increased interest in using flammable refrigerants as a single fluid or as a component of a blend has occurred in the industry. This trend is based on the favorable thermodynamic properties of flammable refrigerants in formulating low ODP and GWP blends. In addition to known hydrocarbons, a wide array of new fluids (mildly flammable synthetic refrigerants) and their blends have been brought to the market.

To be marketed in the US, new refrigerant blends need to have both a Refrigerant Designation Number (R Number) and be assigned a Safety Classification. These factors are determined through a rigorous testing process that conforms to the requirements of ANSI/ASHRAE Standard 34 -2016, Designation and Safety Classification of Refrigerants.

This paper will provide an overview of flammability parameters and refrigerant safety classes, and include a summary of ongoing codes and standards activities related to development and increasing commercial use of flammable refrigerants. It will also provide a review of the basic methods used to assess risk associated with their use.