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EPA 608 Core Exam·Substitute Refrigerants & Oils

What type of oil is typically used with CFC and HCFC refrigerants?

  1. APolyolester (POE)
  2. BPolyalkylene glycol (PAG)
  3. Mineral oil
  4. DVegetable oil

Correct answer

Mineral oil

Why

Mineral oil is typically used with CFC and HCFC refrigerants like R-12 and R-22 because of its miscibility with these refrigerants.

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.

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Exam-style practice question. Not an official EPA exam question.