Rotary Air Compressors: The Advantages of Rotary Vane Compressors

Picture of a rotary vane air compressorThere are basically two types of rotary air compressors readily available on the market today: rotary screw compressors and rotary vane compressors. Rotary vane technology has been available for about fifty years and represents a proven technology that offers a number of advantages over alternative types of air compressors, including the more common rotary screw compressors.

One of the key benefits of rotary vane air compression is that the engine (typically electric, though there are models available that can run on gasoline, diesel, or propane) is directly connected to the compression vanes through a machined bell housing. This means that there is no gear box or v-belt involved, which are frequently some of the most high maintenance elements of other types of compressors. Quite simply, the engine is directly coupled to the compression mechanism without any additional mechanical elements in between the two, eliminating most power transference problems.

Another key advantage of the rotary vane compressor is the fact that it operates on a frictionless basis, without any of the axial thrust that leads to much shorter life spans for bearing in rotary screw compressors. The lack of axial force on the bearings in a rotary vane compressor means that these types of compressors have almost double the running time before a rebuild is necessary, usually in the range of 100,000 to 150,000 hours of actual running time. Related to this is the fact that when bearing failure does occur, it does not result in the same catastrophic damage that frequently accompanies bearing failure in rotary screw compressors. Typically when the bearings fail in a rotary screw compressor, the rotaries come into contact with one another resulting in major damage to the rotors and shafts (as well as the housing in many cases); but none of this is applicable to a rotary vane compressor.

Rotary vane compressors also tend to be much more energy efficient than other types of air compressors. The normal rotational speed of a rotary vane compressor is usually considerably lower (usually around 1,750 RPM) than that of the rotary screw compressors (frequently between 2,500 and 8,000 RPM). The lower speeds mean not only that there is less wear and tear on the machinery, but also that the unit can run longer on less externally supplied energy. Further, by there very design, vanes are more or less self-correcting, meaning that the unit runs at 100 percent efficiency even over time, without the usual loss of efficiency that creeps in over time with other compressors. The self-adjusting nature of vanes also means that there is less fluctuation in the regular output of rotary vane compressors as opposed to others.

Finally, the basic design and functioning of rotary vane technology is simpler than that of many other types of compressors, meaning that maintenance is both easier and less expensive. Most rotary vane compressors only have two bearings, as opposed to the six to eight that are common in similarly sized rotary screw compressors. Similarly, most rotary vane compressors have only two oil line connections and one air line connection, as opposed to the fourteen or more lubrication and control connections found in many rotary screw compressors. Not only does this smaller number of connections mean that rotary vane compressors have a lot less that can go wrong, but it also means that routine overhauls, maintenance and repairs are much easier and less expensive to deal with.

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