What happens to an R-123 chiller when air builds up in it?
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
What happens to an R-123 chiller when air builds up in it?
- Condensing pressure falls and capacity rises
- Condensing pressure rises and efficiency dropsCorrect answer
- Evaporator pressure rises above atmospheric
- Nothing changes until the air reaches the compressor
Why “Condensing pressure rises and efficiency drops” is correct
Air in the condenser adds its own pressure to the refrigerant's and takes up surface that should be condensing refrigerant. Head pressure rises, the compressor works harder, and efficiency falls.
Source: EPA: Test Topics
Why the other answers are wrong
- Condensing pressure falls and capacity rises — Air raises condensing pressure, it does not lower it.
- Evaporator pressure rises above atmospheric — Air collects in the condenser and does not lift the evaporator above atmosphere.
- Nothing changes until the air reaches the compressor — Noncondensables hurt performance as soon as they collect in the condenser.
Practice more of this
More EPA 608 Type III practice questions, or see every EPA 608 practice test.
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