There are a number of factors to consider when selecting an air compressor that will best suit your needs. One of these is whether a fixed-speed or variable-speed air compressor will be the best solution for your application. So, what exactly is the difference?

Variable-Speed Rotary Screw Compressors

Variable-speed compressors maintain a constant air pressure and the motor speed will be adjusted to meet the air demand of your production. Variable-speed compressor units can run on 100% flow or can fluctuate to less flow to conserve energy and align with the current air demand.

The benefits of a variable-speed air compressor are:

  • Reduced energy consumption (in the proper application)
  • Quieter than a fixed-speed compressor when running at a lower RPM
  • Consistent plant pressure
  • Increased component lifetime
  • Low inrush current during motor starts
  • May qualify for energy incentives

Fixed Speed Rotary Screw Compressor

Fixed-speed compressors run either full throttle or are switched off. These are ideal in applications where there is a constant compressed air demand 24/7. The machine will run at a constant RPM unless turned off. The inlet valve will flutter based on when air is needed or not needed instead of ramping the engine up and down.

The benefits of a variable-speed air compressor are:

  • Lower capital cost
  • Increased parts availability
  • Lower maintenance and repair costs
  • More efficient in applications with a consistent demand

Source: Chicago Pneumatic Australia (link to