Rotors are key driving mechanisms in rotary air compressors, an innovative and popular air compressor design. These types of air compressors are classified as displacement compressors, in which air is mechanically compressed to a set pressure. While other types are dynamic compressors, in which air is drawn in, accelerated to high speed and passed through a diffuser to create pressurized air.



In order to fully understand how rotary air compressors work, it is helpful to precisely answer the question, “What is a rotor?” In a rotary screw air compressor, a rotor is a cylindrical piece of equipment with several lobes (or protrusions) that fit together with other lobes to create small channels by which to pressurize and compress air. So, what do rotors do? They rotate at a high velocity, spinning the flowing medium and reducing the volume of air as it flows between the lobes of the rotor.



What to Consider in a Compressor Rotor

There are several factors that one most consider when selecting a compressor rotor and, in the bigger picture, selecting an air compressor product. These factors may include:

  • The application at hand: For what is the compressor being used? Will it be powering the compressed air needs of an entire facility; will it be dedicated to a specific department; or will it be used for one specific machine? Understanding the compressor’s intended usage should help you select the right equipment.
  • The capacity required: How much compressed air should the compressor be capable of providing per minute?
  • Will you require air storage? Some compressors come equipped with air storage tanks, while facilities may also choose to purchase aftermarket tanks. Tanks help build up a supply of compressed air to ensure uninterrupted supply, even during peak usage.
  • The portability of the unit: Some compressors are designed to be mobile and can be used in remote settings, while others are designed to be installed permanently in a facility.


There are also a couple qualities of the rotor itself that you must consider, in addition to how it will be used. These include:

  • RPM: Rotor speed is rated in RPM, or revolutions per minute. RPM is the number of times per minute that a rotor makes one complete turn around the shaft. Rotor design dictates specific maximum and recommended RPM for different types of rotors, depending on material, quality and design.
  • Torque: Torque is the turning force that the motor driving the rotor can provide. As more air enters the chamber and becomes more compressed, more force is required to achieve the required level of pressure. As a motor approaches its maximum rated torque, it becomes less efficient, which may drive up power costs and increase wear and tear on components.

With this information, you now understand the basics of rotors as they are used in air compressors, how they work, and what to consider in choosing the right rotor and compressor. This should ultimately help you improve equipment performance and boost efficiency.

Kaishan Compressor USA Is Ready to Help!

At Kaishan Compressor USA, we specialize in rotary screw compressors, with a broad range of configurations, designs and capacities available, so you can choose exactly the right piece of equipment for your facility and application. We offer exceptional quality backed by an industry-leading warranty program designed to help us build long-lasting, ongoing relationships with our customers. We also offer air compressor components, including filters, and feature several options: single stage or two stage, belt-drive or direct-drive, and more.


Questions?Contact Us Today.