USCG Exam PracticeAir conditioning, ventilation, and compressed air
What is the primary reason high-pressure starting air for large diesel engines is compressed in two or more stages rather than a single stage?
- A. A single-stage compressor cannot produce sufficient volume of air.
- ✓ Compressing to high pressure in a single stage generates excessive heat.Correct
- C. Single-stage compression introduces too much oil mist into the receiver.
- D. Multi-stage compression eliminates the need for relief valves on each stage.
Why B is correct
NAVEDTRA 14075 §7-1 and NAVEDTRA 14104 §10-3 both state that high-pressure air is compressed in two or more stages because compressing to high pressure in one step generates excessive heat. Intercoolers between stages remove that heat of compression and also condense out moisture.