Sliding Vane Compressors: How they Work

When it comes to air compressors there are many different types to choose from. Each compressor performs differently and have their own benefits and downfalls. In this case we will be taking a look a Sliding Vane Compressor which is a positive-displacement compressor. Positive-displacement type compressors have a given amount of air or gas that gets trapped in a compression chamber. From there the volume of that air is mechanically reduced causing an increase in the pressure. Sliding vane compressors use a circular stator that is housed in a cylindrical rotor; the rotor contains radially positioned slots where the vanes reside. These vanes are what create the compression in the “cells”.

Diagram of a sliding vane compressor

The inlet port on the system is positioned in a way that allows the air flow into each cell, optimizing the amount of air that each cell can hold. Once the air enters the system the cell size is reduced down farther and farther as rotation continues and each vane is pushed back into its original slot in the rotor. Compression will continue until each cell reaches the discharge port. One of the more common forms of a sliding vane compressor is the lubricant injected variety. These compressors inject a lubricant into the chamber to lubricate the walls and the vanes; this removes the heat of compression, as well as provide a seal on the cell. These air compressors are generally sold in a 10 – 200 HP range with capacities running between 40 – 800 acfm.

Advantages of a lubricant injected sliding-vane compressor include:

  • Compact size
  • Relatively low purchase cost
  • Vibration-free operation does not require special foundations
  • Routine maintenance includes lubricant and filter changes

Some of the disadvantages that come with this type of compressor:

  • Less efficient than the rotary screw type
  • Lubricant carryover into the delivered air will require proper maintenance of an oil-removal filtration system
  • Will require periodic lubricant changes

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Photo Credit to Compressed Air Challenge Handbook

About Sliding Vane Air Compressors

In positive-displacement type compressors, a given quantity of air or gas is trapped in a compression chamber. The volume of this air is then mechanically reduced, causing an increase in pressure. A sliding-vane compressor will consist of a circular stator that is housed in a cylindrical rotor. The rotor then has radially positioned slots where the vanes reside. While the rotor turns on its axis, the vanes will slide out and contact the bore of the stator wall. This creates compression in these “cells”.

An inlet port is positioned to allow the air flow into each cell, allowing the cells to reach their maximum volume before reaching the discharge port. After passing by the inlet port, the size of the cell is reduced as rotation continues and each vane is then pushed back into its original slot in the rotor.  Compression will continue until the cell reaches the discharge port. The most common form of sliding-vane compressor is the lubricant injected variety. In these compressors, a lubricant is injected into the compression chamber to act as a lubricant between the vanes and the stator wall, remove the heat of compression, as well as to provide a seal. Lubricant injected sliding-vane compressors are generally sold in the range of 10-200 HP, with capacities ranging from 40-800 acfm.

 

Sliding Vane
Air enters from the right, and as the compression chamber volume reduces due to counterclockwise rotation, the pressure increases until the air discharges to the left

Advantages of a lubricant injected sliding-vane compressor include:

  • Compact size
  • Relatively low purchase cost
  • Vibration-free operation does not require special foundations
  • Routine maintenance includes lubricant and filter changes

Some of the disadvantages that come with this type of compressor:

  • Less efficient than the rotary screw type
  • Lubricant carryover into the delivered air will require proper maintenance of an oil-removal filtration system
  • Will require periodic lubricant changes

With the host of different options in compressor types available on the market, EXAIR recommends talking to a reputable air compressor dealer in your area to help determine the most suitable setup based on your requirements. Once your system is up and running, be sure to contact an EXAIR Application Engineer to make sure you’re using that compressed air efficiently and intelligently!

Jordan Shouse
Application Engineer
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Photo Credit to Compressed Air Challenge Handbook