🔍 Key Concepts

• Reciprocating air compressor stages and why multiple stages are used • How a differential piston is shaped (different diameters on one piston rod) • The relationship between piston area, pressure, and force in compressors

💭 Think About

• Which of these choices describes something that could be done with different effective piston areas in the same stroke? • If you wanted to get air from low pressure up to high pressure efficiently, how could a single piston with two different diameters help? • Look at each option and ask: does this require two different cylinder volumes/areas working together, or is it just a control feature?

✅ Before You Answer

• Verify which choice involves sequential pressure increase from a lower to a higher pressure in one piston assembly • Check whether unloading during start‑up is usually handled by valve arrangements or by piston geometry • Confirm which option clearly depends on having more than one effective piston area on the same piston rod