Final answer:
Synthetic oils commonly used in HFC systems and for retrofitting HCFC equipment to HFC refrigerants include POE and PAG oils, needed for system compatibility and efficiency. CFCs and HCFCs are being phased out due to environmental concerns, making way for HFCs, despite their own environmental impact.
Step-by-step explanation:
The type of synthetic oils that are commonly used in new hydrofluorocarbon (HFC) systems and for retrofitting hydrochlorofluorocarbon (HCFC) equipment to HFC refrigerants are Polyol Ester (POE) oils and Polyalkylene Glycol (PAG) oils. These oils are compatible with HFC refrigerants, like HFC-134a, and are often used when transitioning away from HCFC refrigerants, such as HCFC-22, HCFC-123, and HCFC-124. It's important to use the correct oil to maintain system compatibility and efficiency during and after retrofitting.
Additionally, older CFCs like carbon tetrachloride and refrigerants such as dichlorodifluoromethane (R-12 or Freon-12) have been phased out due to their environmental impact, specifically their contribution to ozone depletion. HCFCs like HCFC-141b have also been used as retrofit solutions but are in the process of being phased out as well. As we move away from CFCs and HCFCs, HFCs have been developed as replacements, although they also present environmental concerns, particularly their greenhouse gas potential.