Besides air itself, what harmful contaminant comes into a low-pressure chiller when room air leaks in…
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
Besides air itself, what harmful contaminant comes into a low-pressure chiller when room air leaks in through a joint on its vacuum side?
- Moisture from the surrounding airCorrect answer
- Compressor oil from other machines
- Carbon dioxide that freezes in the tubes
- Higher-pressure refrigerant such as R-22
Why “Moisture from the surrounding air” is correct
Outside air carries water vapor. When a vacuum-side leak draws air in, moisture comes too, and moisture in a chiller can form acids and damage the machine. The purge unit helps remove it.
Source: EPA: Test Topics
Why the other answers are wrong
- Compressor oil from other machines — Oil does not come in from outside through a leak.
- Carbon dioxide that freezes in the tubes — Air holds only a trace of carbon dioxide, and it does not freeze at chiller temperatures.
- Higher-pressure refrigerant such as R-22 — Other refrigerants are not drawn in from room air in any meaningful amount.
Practice more of this
More EPA 608 Type III practice questions, or see every EPA 608 practice test.
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.