USCG Exam PracticeAir conditioning, ventilation, and compressed air
Why must high-pressure air for diesel starting be compressed in two or more stages rather than a single stage?
- A. A single stage cannot produce sufficient volume for the air receiver
- ✓ Compressing to high pressure in a single stage generates excessive heatCorrect
- C. Single-stage compressors cannot be fitted with suction reed valves
- D. Moisture separators are only effective between compression stages
Why B is correct
Both NAVEDTRA 14075 §7-1 and NAVEDTRA 14104 §10-3 state that high-pressure air is compressed in two or more stages because compressing to high pressure in one step generates excessive heat. An intercooler between stages removes that heat and also condenses out moisture.