EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Hard
During a routine inspection of a low-pressure chiller, a technician observes oil in the purge unit's sight glass. What does this observation most likely indicate?
- AAir and other non-condensables are entering the system, carrying oil with them.
- BThe chiller's compressor is overcharged with lubricant.
- CThere is excessive moisture in the system, causing oil to separate.
- DThe purge unit is operating correctly and efficiently removing contaminants.
Show answer & explanationAnswer & explanation
Correct answer: A. Air and other non-condensables are entering the system, carrying oil with them.
Oil in the purge unit sight glass typically indicates that air and other non-condensables are continuously entering the system. As non-condensables are drawn into the purge unit, they can carry oil vapor or mist from the chiller's refrigerant circuit, which then collects in the purge unit.
Why the other options are wrong
- B. While overcharging with lubricant could contribute to oil circulation, the direct observation of oil in the purge unit strongly points to air ingress as the primary mechanism for oil to be carried to the purge unit.
- C. Excessive moisture might cause other issues but wouldn't directly lead to oil in the purge unit's sight glass; air ingress is the more direct cause.
- D. Oil in the sight glass indicates a problem, not correct operation. A correctly operating purge unit should primarily be removing non-condensables and some moisture, not significant amounts of oil.
Purge Unit Oil Indication
The presence of oil in a low-pressure chiller's purge unit sight glass is a strong indicator of a persistent leak allowing air and other non-condensables into the system.
- Purge unit removes non-condensables.
- Air ingress carries oil mist.
- Indicates a system leak.
Memory trick: Oil in the purge? Air's on the surge!