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This page groups compressors rated roughly 48 to 54 CFM. That is the full output of a 15 HP two stage piston compressor from Champion or Atlas Copco, a 15 HP fixed speed rotary screw such as the Chicago Pneumatic QRS 15 or Atlas Copco G7L 15, a 10 HP high output screw such as the Atlas Copco GA7 VSDS, or a 20 HP Quincy QGSV variable speed screw at its top rating. Champion R series duplex sets and the SpiralAir multi scroll packages fill in the rest.
Who buys 50 CFM
A twelve to fifteen bay dealership, a truck fleet shop, a machine shop running several CNC machines with air blast, a plastics shop with pneumatic presses, or a mid size body shop. At this size most shops are on their second or third compressor and know whether the machine will run intermittently or all day. If it runs all day, buy the rotary screw; if it runs in bursts and price matters, the 15 HP two stage piston on a 120 gallon tank is still hard to beat.
Power and installation
Three phase only. A 15 HP piston motor at 230 volt draws about 42 full load amps and needs a 60 amp circuit; a 15 HP screw is similar. Piston units at this size should sit on a concrete pad with isolation pads and have 24 to 36 inches of clearance for the flywheel and cooling air. Rotary screws need clearance on the fan side and a receiver tank of 120 to 240 gallons.
Dryer sizing
Pair a 50 CFM compressor with a 60 to 75 CFM refrigerated dryer. For paint, powder coating or instrument air add a coalescing filter, and consider a desiccant dryer where lines run outdoors or through unheated space.
