What is the main job of the purge unit on a low-pressure chiller?
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 is the main job of the purge unit on a low-pressure chiller?
- Remove oil from the refrigerant
- Add refrigerant when the charge is low
- Pump down the evaporator for service
- Remove air and other noncondensablesCorrect answer
Why “Remove air and other noncondensables” is correct
Low-pressure chillers run partly below atmospheric pressure, so air and moisture can leak in. The purge unit removes these noncondensables and returns the refrigerant it separates from them to the chiller.
Source: EPA: Test Topics
Why the other answers are wrong
- Remove oil from the refrigerant — Oil separation is not the purge unit's job.
- Add refrigerant when the charge is low — The purge unit does not charge refrigerant.
- Pump down the evaporator for service — Pump-down is done with recovery equipment or a pump-out unit, not the purge.
Practice more of this
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