This page lists compressors rated roughly 65 to 74 CFM. Piston options are 20 HP two stage duplex sets: the Chicago Pneumatic RCP-C Iron duplex and the Atlas Copco CR duplex both deliver 70 to 73 CFM at 175 PSI from two 10 HP cast iron pumps. Rotary screw options are the Atlas Copco GA15 at 71 CFM and the Quincy QGSV 20 HP variable speed screw at 72 CFM. The Quincy QOF and Chicago Pneumatic SpiralAir multi scroll packages reach 65 CFM oil free.

What 70 CFM supports

A plant with 15 to 20 stations of steady pneumatic tooling, a large body shop with three or four booths, a foundry or forge shop, a precast or block plant, or a fleet maintenance facility with tire machines, lifts and impact tools on the line at once. At this size the compressor is a piece of plant equipment and usually gets its own room with ducted cooling air.

Duplex piston vs 20 HP rotary screw

The duplex piston sets are chosen for redundancy and simple service; each pump can carry about half the plant on its own. A 20 HP rotary screw such as the GA15 or QGSV 20 runs cooler and quieter, delivers steady pressure, and with variable speed drive can cut energy use 20 to 30 percent on a shop with swinging demand. Screws need a service kit every 2,000 to 4,000 hours and a clean, cool room to reach their rated life.

Power and dryer sizing

Plan on three phase 460 volt where available; a 20 HP motor draws about 27 amps at 460 volt or 54 amps at 230 volt. Pair the compressor with an 85 to 100 CFM refrigerated dryer, or a desiccant dryer where the plant needs a dew point below freezing.

Related pages

• 60 CFM air compressors
• 80 CFM air compressors
• 20 to 50 HP rotary screw air compressors
• Shop all sizes by CFM