Question

Which of the air compressors, is NOT a rotary type compressor?

• A. Screw type compressor
• B. Scroll type compressor
• C. Vane type compressor
• D. Piston type compressor

Hint:

Just look at the names. Screw, Scroll, and Vane all imply something turning or spinning (Rotary). A Piston implies something pumping up and down (Reciprocating).

Answer 1

The Correct Option is D

Air compressors are primarily classified based on their principle of operation: Positive Displacement (Reciprocating or Rotary) and Dynamic (Centrifugal or Axial). 1. Rotary Type Compressors: These compressors use rotating elements (rotors, screws, or vanes) to trap and compress air. They are known for providing a continuous, pulse-free flow of air.

• Screw Type: Uses two intermeshing helical screws.

• Scroll Type: Uses two spiral-shaped elements (one fixed, one orbiting).

• Vane Type: Uses a rotor with sliding vanes inside an eccentric housing.

2. Reciprocating Type Compressors: The

Piston type compressor is the classic example of a reciprocating compressor. It uses a piston driven by a crankshaft to move back and forth inside a cylinder.

• Suction occurs as the piston moves down.

• Compression occurs as the piston moves up.

3. Conclusion: Because the piston type relies on linear "back-and-forth" motion rather than continuous circular motion, it is categorized as a

Reciprocating compressor, and therefore is NOT a rotary type.