Rotary Screw Basics

June 26, 2014

There are many types of air compressors.  You need to evaluate your purpose before you decide if a rotary screw air compressor is what you need.  Air compressors are used to power small tools like automotive ratchets and construction nail guns.  Large Air compressors like rotary screw or centrifugal air compressors are used for industrial applications and can power a whole factory.

If you need a steady flow of air to power your equipment without interruption rotary screw is for you.  Rotary compressors can provide a source of power to drive punching and stamping machines.  Compressed air can also power robotic equipment.

Sandblasters and paint sprayers use the air directly.  A steady flow of air pressure is critical in a paint spraying application.
Gas powered rotary air compressors do not have pistons.  They have two twin screws next to each other that push the air to higher levels.  Most rotary screw compressors are oil-cooled.  The air is pushed into an oil filled chamber and creates a hydraulic seal.  The hot oil is then separated, cooled and recycled.  Oil cooled rotary air compressors are smoother running than reciprocating air compressors and do not require spring suspension.

Maintenance is very important to insure the productivity of your rotary screw air compressor.
The gas-oil separator must be drained periodically.  Be sure to follow the manufacturer’s maintenance schedule.  A positive feature of screw air compressors is that there are less moving parts which keep maintenance costs down.

Oil-less models are available for industries where oil carryover is not acceptable, such as pharmaceutical companies, hospitals and electronic manufacturers to name a few.  They usually have a lower discharge capability than the oil flooded models.  Prices on oil less models are substantially more.

Rotary screw air compressors cost a bit more than a piston type air compressor but you must consider the fact that they last longer and the power they produce to get your job done more efficiently.  When making a large purchase like this be sure to consider future needs.  Rotary screw air compressors can last over 50,000 hours and average 20 years.  What do you think your needs will be in two to three years?  Will you have more employees running more tools at the same time?  Investing a little more today could save you much more in a few years.

Whether you are purchasing a new or used rotary air compressor consider these points when making your final choice.

  • How long has the air compressor manufacturer been in business?
A company that has been making air compressors for over 15 years is a good choice; they are likely to be around to support you for years to come.
  • Do they specialize in air compressors?
There are companies that mainly sell tools and only provide customers with air compressors as a convenience.
  • Support and Staff
Does the company have knowledgeable employees to help you in your time of need?
Is there local help should an emergency arise?
  • Purchase New or Used?
Do not rule out the possibility of purchasing a used air compressor.  Many companies are relocating or closing due to today’s economy.  This could be a great opportunity for you.
Many reputable distributors have quality used air compressors for sale.  There are many used units available at for your comparison.

Are you specifically looking to buy a used rotary screw compressor? Then read our latest blog post about buying a used air compressor the smart way.