EPA Section 608 Universal Certification ExamCoreMedium
A technician is installing a new commercial refrigeration system that will operate with R-404A. Which of the following statements about the oils used with R-404A is correct?
- AR-404A is compatible with any synthetic oil.
- BR-404A requires the use of polyolester (POE) oil.
- CR-404A is compatible with mineral oil.
- DR-404A requires the use of alkylbenzene oil.
Show answer & explanationAnswer & explanation
Correct answer: B. R-404A requires the use of polyolester (POE) oil.
R-404A is an HFC refrigerant blend. HFCs are not miscible with traditional mineral or alkylbenzene oils and require the use of synthetic polyolester (POE) oils for proper lubrication and refrigerant return.
Why the other options are wrong
- A. Not all synthetic oils are compatible; specifically, POE oil is required for HFCs, not just 'any' synthetic oil.
- C. Mineral oil is used with CFCs and HCFCs, not HFCs like R-404A.
- D. Alkylbenzene oil is primarily used with HCFCs, not HFCs like R-404A.
HFC Refrigerant Oils
HFC refrigerants, being non-chlorinated, require synthetic polyolester (POE) oils for proper lubrication and miscibility within the refrigeration system.
- HFCs require POE oil.
- POE oil is highly hygroscopic.
- Mineral oil and alkylbenzene oil are not compatible with HFCs.
- Proper oil selection is critical for system longevity.
Memory trick: HFCs need POE, like a 'POE'm needs to be 'heard' (H-rd).