🔍 Key Concepts

• Role of a sight glass in refrigeration systems (what phase of refrigerant you want to observe) • Typical flow order in a multi-box marine refrigeration system: compressor → condenser → receiver → liquid line → expansion devices → evaporators → suction line → compressor • Difference between high-pressure liquid line and low-pressure suction line

💭 Think About

• Ask yourself: At what point in the system do you most need to visually confirm that you have a solid column of liquid refrigerant and no bubbles? • Think about whether a sight glass would be more useful where refrigerant is mostly vapor, mostly liquid, or a mixture of both. • Which part of the system feeds the expansion valves for multiple boxes, and where would a single sight glass best serve a multi-box setup?

✅ Before You Answer

• Identify which of the answer choices are in lines that normally carry liquid refrigerant versus vapor refrigerant during normal operation. • Confirm where in the cycle you want to detect bubbles indicating a shortage of liquid refrigerant. • Check which location is typically on the high-pressure liquid line supplying all the evaporators in a multi-box system.