What is a common characteristic of HFC refrigerants?

HFC refrigerants, or hydrofluorocarbons, are commonly recognized for their non-flammable properties. This characteristic makes them safer to use in many applications when compared to other refrigerants that pose flammability risks. Non-flammability contributes to the widespread adoption of HFCs in the refrigeration and air conditioning industries, as it enhances safety in both usage and storage.

The other options do not accurately reflect the properties of HFCs. While they are indeed less harmful to the ozone layer compared to some older refrigerants (like CFCs), they are not without environmental impact, particularly regarding global warming potential. HFCs can have a significant greenhouse gas effect, which contradicts the assertion of zero environmental impact. Additionally, HFCs are generally efficient in their functioning and performance, so they are not characterized by low efficiency.