USCG Exam PracticeRefrigeration principles and systems
The sight glass in the liquid line of a refrigeration system is showing a steady stream of bubbles. Which condition does this MOST likely indicate?
- A. The system is overcharged and head pressure is elevated
- ✓ The system is undercharged or there is a restriction upstream of the sight glassCorrect
- C. Non-condensable gas has collected in the evaporator
- D. The compressor is operating with unloaded cylinders
Why B is correct
NAVEDTRA 14075 §6-3 states that a sight glass showing bubbles indicates the system is undercharged or restricted. A fully charged system shows solid liquid. An overcharge raises head pressure but does not cause bubbles in the liquid line.
Cited:NAVEDTRA 14075 §6-3