Which of the following is the compression ratio for a rotary vane compressor?

Which of the following is the compression ratio for a rotary vane compressor?

• A. 8:1
• B. 20:1
• C. 4:1
• D. 6:1

Answer: (C)

Rotary vane compressors achieve compression through a single‑stage, positive‑displacement action: air is trapped between a rotor vane and the housing, and as the rotor turns the trapped air’s volume is reduced, increasing pressure. The compression ratio is the factor by which the intake volume is reduced to the discharge volume. For this design, that reduction is typically about four to one, which is why four-to-one is the standard compression ratio for a rotary vane unit. Higher ratios would require more aggressive volume reduction or a multi‑stage setup, which isn’t characteristic of a basic rotary vane compressor.

Rotary vane compressors achieve compression through a single‑stage, positive‑displacement action: air is trapped between a rotor vane and the housing, and as the rotor turns the trapped air’s volume is reduced, increasing pressure. The compression ratio is the factor by which the intake volume is reduced to the discharge volume. For this design, that reduction is typically about four to one, which is why four-to-one is the standard compression ratio for a rotary vane unit. Higher ratios would require more aggressive volume reduction or a multi‑stage setup, which isn’t characteristic of a basic rotary vane compressor.