Which compression ratio is associated with a high-speed reciprocating compressor?

• A. 6:1
• B. 12:1
• C. 8:1
• D. 20:1

Answer: (C)

High-speed reciprocating compressors keep the pressure rise per stage relatively modest to control heat, stress, and lubrication challenges that come with fast piston motion. The typical per-stage compression ratio for these fast machines is about eight to one, which balances achieving the needed pressure with keeping discharge temperatures manageable. That’s why eight to one is the best fit for a high-speed unit.

Ratios like six to one can occur, but they’re not the standard association with high-speed operation. Very high per-stage ratios such as twelve to one or twenty to one would require more stages, intercooling, and heavier design changes, which are not characteristic of the common high-speed reciprocating compressor setup.