The Difference Between Piston and Screw Compressors

Ever wonder about the differences between piston compressors and rotary screw compressors? You aren't alone! There are things that mark these technologies as unique - even as they're the two most popular compressor technologies on the market. 

Piston (or reciprocating) compressors are used in many small machine shops, body shops, tire shops, service centers, and small manufacturing facilities; they’re also extremely popular for the DIY-er! Simple and robust, piston compressors are relatively inexpensive and easy to maintain, both of which are advantages. They have many moving parts (such as piston rings, pistons, connecting rods, and valves) and are ideal for applications and businesses where a lower initial price point is needed.

However, their design does come with some limitations. For example:

• Piston compressors are meant for intermittent use. They can work for 50-60% of their duty cycle (about 30 to 35 minutes per hour).
• Piston compressors require proper cooling time between duty cycles, or they will overheat and perhaps fail.
• Piston compressors produce significant oil in the compressed airstream. This must be treated properly to prevent damage to pneumatic piping and equipment.
• Piston compressors are loud in operation, which may be difficult on employees or customers. If these disadvantages don’t impact your operation, a piston compressor may be an economical choice.

Rotary screw air compressors are sophisticated machines designed for operations that require a constant supply of compressed air; in fact, they're engineered to run 24/7! Rotary screw compressors are often equipped with an integrated dryer to provide clean, dry air. They come sizes ranging from a few to a few hundred horsepower. Some units are mounted on an air tank to provide additional storage capacity. Integrated systems combine the compressor, dryer and tank in one unit, enabling plug and play installation of a complete system with a small footprint.

Air demand may fluctuate as work progresses. A Variable Speed Drive (VSD) compressor senses demand changes and speeds up or slows down automatically to match production of compressed air to demand. That’s important because energy accounts for over 70% of the total cost of ownership of a commercial air compressor. A VSD compressor can reduce energy costs by 35-50%. VSD air compressors are becoming the norm rather than the exception, with many users reinvesting annual energy savings into their business.