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EPA 608 Core Exam·Substitute Refrigerants & Oils

At what pressure does R-410A typically operate on the high side compared to R-22?

  1. AAbout the same pressure
  2. BAbout 50% higher pressure
  3. About 60% higher pressure
  4. DAbout twice the pressure

Correct answer

About 60% higher pressure

Why

R-410A operates at approximately 60% higher pressures than R-22, requiring equipment rated for higher pressures.

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

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