During normal operation, which part of an R-123 chiller is most likely to be above atmospheric pressure?

Refrigeration · EPA 608 Type III. The correct answer, and the reasoning behind it.

Purge units and pressure-temperature behaviour of low-pressure refrigerants.

The question

During normal operation, which part of an R-123 chiller is most likely to be above atmospheric pressure?

• AThe evaporator
• BThe compressor suction
• CThe condenserCorrect answer
• DThe cooler liquid line

Why “The condenser” is correct

R-123 condenses at temperatures above its 82 °F boiling point, so the condenser can sit slightly above atmospheric pressure. The evaporator, working at chilled-water temperatures, stays in a vacuum.

Source: EPA: Test Topics; Hudson Technologies R-123 and R-11 P-T charts

Why the other answers are wrong

• The evaporator — The evaporator of a low-pressure chiller runs in a vacuum.
• The compressor suction — The suction side is at evaporator pressure, below atmosphere.
• The cooler liquid line — Liquid feeding the evaporator is near evaporator pressure, not condenser pressure.

Practice more of this

More EPA 608 Type III practice questions, or see every EPA 608 practice test.