Refrigeration Operating Engineer License Practice Exam 2025 - Free Practice Questions and Study Guide

HFC-123a is a suitable permanent replacement for CFC-11 in reciprocating compressors due to its chemical properties and performance characteristics. CFC-11, which was widely used in refrigeration and air conditioning systems, is an ozone-depleting substance. As regulations have tightened to protect the ozone layer, alternatives needed to be found that do not carry the same environmental impact.

HFC-123a does not contain chlorine, which means it does not harm the ozone layer like CFCs and HCFCs. It has been designed to provide a balance of efficiency, effectiveness, and lower environmental impact. Additionally, in terms of thermodynamic properties, HFC-123a operates effectively in systems designed for CFC-11, making it a more seamless substitute in existing applications.

In comparison, while HCFC-22 and R-404A also present alternative options, they do not serve as permanent replacements for CFC-11 in the same way. HCFC-22 still contains chlorine, posing a risk to the ozone layer, and R-404A is a blend that is being phased down for its high global warming potential. Therefore, HFC-123a stands as the most aligned with modern refrigerant standards aimed at protecting the environment