The Refrigerant Compliance Glossary

A blend whose components evaporate and condense across a range of temperatures rather than at one point. Identified by 400-series numbers, including R-410A, R-407C, and R-448A.

A blend that evaporates and condenses at essentially a single temperature, behaving like a pure refrigerant. Identified by 500-series numbers such as R-500 and R-507A.

A mixture of two or more refrigerants formulated to hit target properties — capacity, GWP, flammability, oil compatibility. Most modern commercial refrigerants are blends, identified by 400- or 500-series numbers.

The letter half of an ASHRAE 34 designation: A for refrigerants with lower chronic toxicity, B for higher. Ammonia is class B; nearly all fluorinated refrigerants are class A.

The numeric half of an ASHRAE 34 safety designation: 1 for no flame propagation, 2L for mild flammability with low burning velocity, 2 for flammable, 3 for higher flammability such as hydrocarbons.

The standard that assigns each refrigerant a designation number and a safety class combining toxicity (A = lower, B = higher) and flammability (1 = none, 2L = mild, 2 = flammable, 3 = higher flammability). R-410A is A1; R-454B is A2L; ammonia is B2L.

A refrigerant classified as lower toxicity and mildly flammable under ASHRAE Standard 34. R-32 and R-454B are the common commercial examples, both replacing R-410A in new equipment.

Unsaturated fluorinated refrigerants with very low global warming potential, such as R-1234yf and R-1234ze. Often blended with HFCs to hit a target GWP while managing flammability and capacity.

Fluorinated refrigerants with no ozone impact but often high global warming potential — R-410A, R-134a, R-404A, R-407C. They are the target of the AIM Act phasedown.

Transitional refrigerants with lower ozone impact than CFCs, R-22 being the dominant example. Production and import ended January 1, 2020.