From which part of a low-pressure chiller does the purge unit normally draw its sample?

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

From which part of a low-pressure chiller does the purge unit normally draw its sample?

• AThe top of the condenserCorrect answer
• BThe bottom of the evaporator
• CThe compressor oil sump
• DThe chilled-water return line

Why “The top of the condenser” is correct

Noncondensables travel with the refrigerant vapor to the condenser, where the refrigerant condenses and the air does not. The air gathers at the top of the condenser, so that is where the purge draws from.

Source: EPA: Test Topics

Why the other answers are wrong

• The bottom of the evaporator — Noncondensables do not collect at the bottom of the evaporator.
• The compressor oil sump — The oil sump is not where noncondensables gather.
• The chilled-water return line — The water circuit is separate from the refrigerant circuit.

Practice more of this

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