Refrigerants are classified into toxicity and flammability levels for safety and use in HVAC systems. Safety organizations make determinations of potential hazard by classifying refrigerants based on what would happen should a human inhale, ingest, or touch the gas.

The organizations responsible for these classifications are the
American Society of Heating, Refrigerating and Air Conditioning Engineers(ASHRAE)
National Fire Protection Association(NFPA)
Hazardous Material Identification System(HMIS)
National Refrigeration Safety Code(NRSC)
National Board of Fire Underwriters(NBFU)







The primary body impacting refrigerant classifications is the American Society of Heating, Refrigerating and Air Conditioning(ASHAE). They have divided refrigerants into two different categories. Class A refrigerants have not been identified as being toxic and their levels have not been determined. Class B refrigerants have been found to be toxic to the human body and levels are known. ASHRAE along with guidelines by the Environmental Protection Agency have made a determination that 400 PPM would be the cut off point for non-toxic vs toxic refrigerants.









Common refrigerants have further been classified into three primary categories indicated their levels of flammability. A number one indicates no flammability has been identified. A number two indicates low flammability. Number three indicates a high flammability.

The following is information showing the refrigerant number, level of toxicity, and level of flammability.
R-11 A1
R-12 A1
R-22 A1
R-123 B1
R-124 A1
R-125 A1
R-134a A1
R-401A A1
R-406A A2
R-500 A1
R-502 A1
R-507A A1
R-717 B2
R-744 A1

Environmental Concerns

In addition to the potential harm that could be done to humans directly, safety organizations concern themselves with the intensity, duration, and frequency of harm that can come from refrigerant classifications to the environment.

The average American has become familiar with words and phrases like ”ozone depletion,” ”environmental sustainability,” and ”ecosystems.” These words point to the fact that our world has become more environmentally sensitive over the last few decades. Legislation, economic policy, and the creation of new technologies are all governed by an over arching concern with the environment.

Because of this concern, refrigerants must be stored, administered, introduced to air conditioning systems, and disposed of according to certain, legal guidelines that insure the safety of people and the protection of the environment.