- AA blend that separates easily
- A blend that behaves like a single refrigerant and doesn't fractionate
- CA blend containing oil
- DA blend with multiple boiling points
Correct answer
A blend that behaves like a single refrigerant and doesn't fractionate
Why
Azeotropic blends behave as a single refrigerant - they don't fractionate and have a single boiling point at a given pressure (e.g., R-502, R-507).
The concept behind this question
Substitute refrigerants have to be evaluated as a system with their lubricant, not swapped in isolation. Mineral oil works with CFCs and HCFCs but does not circulate properly with most HFCs, which is why HFC systems generally use polyolester (POE) oil — and POE is strongly hygroscopic, so it absorbs atmospheric moisture fast when left open. Substitutes must also be approved for the specific end use under EPA's SNAP program, and newer A2L refrigerants are mildly flammable, which changes the handling and equipment rules that apply.
More questions on this topic
- Polyolester (POE) oil is used with which type of refrigerants?
- What is the Global Warming Potential (GWP) used to measure?
- What type of refrigerant is R-410A?
- At what pressure does R-410A typically operate on the high side compared to R-22?
- What is a 'blend' refrigerant?
- What is 'fractionation' of a refrigerant blend?
Exam-style practice question. Not an official EPA exam question.