Compressed Air Systems

Compressor Selection

Compressor Selection

How to Choose The Right Compressor


Reciprocating or Rotary Screw

This is a common question asked by most people looking for a new air compressor. Either compressor depends in your application.

If the application requires air all day or has multiple shifts that use air on a consistent basis, then a rotary screw is probably a better fit for the application due to its ability to run all day every day. Rotary Screw compressors are thermally controlled through an air cooled oil cooler. Some rotary screw compressor packages have built in timers that will turn the compressor off if it runs unloaded for an extended period of time. (Everyone goes to lunch, or it does not get turned off at the end of the day.)

Reciprocating compressors are best suited for applications that require air for shorter durations of time and might have 15-30-45 minutes before they need air again. Because a Reciprocating compressor is air cooled, they need to enter an application with a duty cycle of 70% or less. Either package depends on making sure you purchase a properly sized compressor for your application. If you have any questions, you can always contact CAS or one of our local distributors to make sure you have the right unit for your application.

Noise Considerations

The noise of an air compressor package depends on how it is constructed.. Most rotary screw compressors sold in the world today are built in sound dampening enclosures. This does not add to the performance of the compressor package, all they do is lower the DBA of the compressor package. Most reciprocating compressors are built open on a tank with no sound proof enclosure, which is why they sound louder than a rotary screw in a sound dampening enclosure. If you take a reciprocating compressor and build it in the same enclosure as a rotary screw compressor you will get a similar DBA reading. At CAS we manufacture a reciprocating compressor muffler that can lower the DBA of the compressor by up to 10DBA depending on the acoustics or the compressors environment. This would put the DBA of a CAS reciprocating compressor in the range of 74-82DBA. At CAS we are one of the few compressor companies to build an open tank mounted rotary screw compressor while the DBA range is 70-84 depending on the size of the compressor, an enclosed rotary screw compressor package is between 64-78DBA depending on the size. The enclosure for a rotary screw compressor is an added expense up front and to the yearly maintenance cost. It takes longer to service and enclosed rotary screw compressor than an open tank mount version.

Compressor Size

Bigger is not always better. Too large and you pay for more than you need and spend more in operating costs. Too small and you'll find yourself waiting for air and shortening the life of your equipment. Use our sizing guides to help you pick the right compressor. Or give us a call and we'll put you in touch with a local distributor who can size a compressor for your application.