EPA 608 Core · Refrigeration Fundamentals · Hard
When does a PT chart give the actual temperature of a refrigerant from its pressure?
Answer: D. When liquid and vapor are both present.
- AWhenever the compressor is running.
- BOnly when the vapor is superheated.
- COnly when the liquid is subcooled.
- DWhen liquid and vapor are both present.✓ Correct
Why D is right
Pressure and temperature are locked together only at saturation, where liquid and vapor coexist, as in a recovery cylinder or the middle of an evaporator. Superheated vapor is warmer, and subcooled liquid colder, than the PT chart shows for their pressure.
More Core questions
- What does refrigerant do inside the evaporator?
- Which component raises the pressure and temperature of refrigerant vapor?
- What characterizes a zeotropic refrigerant blend (400-series)?
- Which PT chart value do you use to calculate subcooling for a zeotropic blend?
- What happens when a zeotropic blend leaks from a system?
Go deeper with the study guide EPA 608 Core Exam: Study Guide for 2026, try the free 10-question test or browse all EPA 608 practice questions.
A practice question written for study, checked against 40 CFR Part 82, Subpart F. It is not an official EPA exam question, and this site is not affiliated with the U.S. EPA.