50 HP air compressors: 219 to 277 CFM plant air

50 HP is the largest size most plants buy as a single compressor before moving to multiple machines with a sequencer. A fixed speed 50 HP screw delivers 219 to 239 CFM and a variable speed unit up to 277 CFM. That runs a large fleet maintenance facility, a tire plant, a plastics molding floor with 20 or more presses, a textile or paper converting line, or a large shot blast room. Also here is the Chicago Pneumatic CPS 185 KDU, a 50 HP diesel utility mount making 185 CFM for service trucks that need rotary screw air on the road.

What is on this page

Fixed speed rotary screw: Atlas Copco GA30+ to GA37 series (GA37 at 219 CFM at 150 PSI and 239 CFM at 125 PSI), Chicago Pneumatic CPCg 50 gear drive at 219 CFM in 100, 125, 150 and 175 PSI builds with and without the integrated dryer, and Quincy QGS 50 at 125 PSI. Variable speed: Atlas Copco GA37 VSDS at 277 CFM, Atlas Copco GA37 VSD at 247 CFM, Chicago Pneumatic CPVSM 50 at 236 CFM, and Quincy QGSV-50 at 164 CFM and 175 PSI. Diesel: Chicago Pneumatic CPS 185 KDU utility mount, 185 CFM at 100 PSI, Kubota engine. Duplex piston: Champion Duplex R-Series 50 HP (two 25 HP pumps) at 175 PSI. Oil free scroll: Chicago Pneumatic COAIRE CSOF-S 50 multi scroll.

One 50 HP or two 25 HP

Buyers at this size face a real choice between one 50 HP machine and two 25 HP units with a sequencer. One machine costs less to buy and install and takes less floor space. Two machines give redundancy and let the plant run one compressor on weekends or night shift without unloading a large motor. A 50 HP variable speed unit splits the difference: it turns down to about 25 percent of capacity on its own, so a single VSD machine often replaces a two compressor plan. If the plant has a second compressor already, a fixed speed 50 HP as the base load machine is the lowest cost per CFM on this page.

Power, receiver and dryer

Plan on 130 amps at 230 volt three phase or 65 amps at 460 volt; 460 volt is standard at this size and the drives are rated for it. Use a 400 to 660 gallon receiver, a 250 to 300 CFM refrigerated air dryer (or the CPCg integrated dryer package), and plan the compressor room ventilation for 150,000 to 180,000 BTU per hour of heat rejection or duct the cooling air outside.

Related pages

• 40 HP air compressors
• 60 HP air compressors
• 50 HP and up rotary screw air compressors
• 200 CFM air compressors and 250 CFM air compressors
• Variable speed rotary screw air compressors
• Shop by HP, Shop by CFM and Shop by PSI