Oil-Free Rotary Screw Air Compressors: 100% Contaminant-Free Air for Critical Applications

Engineered for maximum energy efficiency, reliable uptime, and strict compliance with ISO Class 0 air quality standards

For food, beverage, chemical, and pharmaceutical manufacturing, even a trace amount of oil air contamination can cause costly downtime, batch destruction, and regulatory fines. KAESER’s oil-free rotary screw air compressors eliminate that risk entirely—delivering 100% oil-free, ISO Class 0 certified air across a complete line ranging from 50 to 450 hp with flow capacities from 140 to 1,770 cfm. 

Engineered around KAESER’s core principles of energy efficiency and reliable uptime, our CSG, DSG, and FSG series lower your total cost of ownership. Every unit features precision-machined airends, accessible service points to minimize routine maintenance time, and optional integrated dryers for complete air treatment in a compact footprint. 

Whether your facility requires an air-cooled or water-cooled installation, fixed-speed or variable-frequency drive, KAESER provides tailor-made configurations designed to handle continuous heavy-duty cycles while reducing power consumption by up to 9%. 

Need temporary clean air or an emergency backup? We also offer the diesel-driven MOBILAIR M500-2, a portable powerhouse delivering up to 1,600 cfm of oil-free air wherever your operation needs it most.

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KAESER Oil-Free Rotary Screw Air Compressor Models

Model Rated Power (hp) Flow Range (cfm) (air-cooled, fixed-speed) Pressure Range (psig) (air-cooled, fixed-speed)
Stationary Oil-Free Compressors
CSG 60 50 186-253 60-160
CSG 75 60 240-317 60-160
CSG 95 75 290-374 60-160
CSG 125 100 431-490 60-160
CSG 150 125 488-570 60-160
DSG 140-2 125 512-581 65-145
DSG 180-2 150 576-694 65-145
DSG 220-2 175 689-820 65-145
DSG 260-2 200 816-966 65-145
DSG 290-2 250 961-962 100-145
FSG 300-2 250 795-1144 90-145
FSG 350-2 300 1148-1391 65-145
FSG 420-2 350 1261-1591 65-145
FSG 500-2 450 1586-1769 125-145
FSG 501-2 450 1766 (water-cooled) 145 (water-cooled)
Notes: All models available air-cooled or water-cooled, except: FSG 501-2 which is only available water-cooled. Most models available with either integrated (T) dryer or i.HOC (heat of compression) dryers. Choose from fixed speed or variable speed drive. See literature for details on each model.
The M500-2 compressed air giant for refineries and large industrial companies
Model Rated Power (hp) Flow Range (cfm)  Pressure Range (psig)
Portable Oil-Free Compressors
M500-2 600 (Caterpillar C18 diesel engine) 1340-1600 100-150
 
 

Audit-Ready Compliance with Class 0 Certification

oil-free certifications

Kaeser oil-free screw compressors meet the world's most stringent purity and efficiency certifications: 

  • ISO 8573-1 Class 0: The gold standard for oil-free air purity. 
  • FSMA & SQF: System designs that simplify your safety audits and regulatory compliance. 
  • BCAS: Adhering to best practices for food-grade compressed air.

Where Oil-Free Rotary Screw Air Compressors Are Critical

compressed air for food processing and packaging

Certain industries cannot tolerate even trace oil contamination in their compressed air supply. In food and beverage production, compressed air may contact products at multiple points on the line, from sorting and ejecting to mixing, packing, conveying powdered ingredients, and cleaning bottles and molds before filling. Any oil in that air creates compliance exposure and product liability risk. 

Pharmaceutical and life sciences facilities face equally strict requirements. Drug manufacturing and medical device production demand purity that meets ISO 8573-1 Class 0 or Class 1 for oil, specifications that only a true oil-free compressor can achieve without depending entirely on downstream filtration. 

Chemical processors need oil-free air to maintain product purity and prevent catalyst and process equipment fouling. Semiconductor manufacturing requires extremely high-purity air where even microscopic particles can cause defects, while automotive and aerospace paint finishing and precision assembly operations rely on contamination-free air to prevent surface defects on high-value components.

Built for Reliability, Serviceability, and Efficiency

Purchasing an oil-free air compressor is a long-term decision. The sticker price accounts for a fraction of total lifecycle cost. Energy consumption dominates over time, which is why Kaeser engineers every detail of the CSG, DSG, and FSG series with efficiency in mind.
 

Reliability

count on Kaeser oil free rotary screw compressors for maximum reliability

The rotors carry a special abrasion-proof coating rated to 575°F that will not wear over time, keeping compressed air delivery and energy consumption consistent across years of operation. Stainless steel rotors in the second compression stage ensure air quality and significantly extend service life. SIGMA CONTROL monitors more than 20 critical operating parameters, stores the last 200 operational events, and offers multiple control profiles to match compressor behavior precisely to process demand.

Serviceability

easy service for oil free screw compressors

In the CSG series, service intervals for compressor stages and gear fluid are 50% longer than in previous designs, condensate drain maintenance intervals are three times longer, and the pulsation dampeners are maintenance-free. On larger models, both stages of the aluminum-block heat exchanger swivel out for cleaning, and the temperature-controlled standstill fan removes residual heat during standby, allowing the main fan to be switched off for quicker service access.

Energy Efficiency

kaeser oil free screw compressors are energy efficient

Kaeser's oil-free rotary screw compressor models are up to 9% more efficient than competing designs. SIGMA FREQUENCY CONTROL (SFC) models use synchronous reluctance IE5 motors, and a speed-controlled radial fan on fixed and variable speed units maintains proper cooling airflow while minimizing power draw. For operations needing sub-freezing pressure dew points, our patented i.HOC (Integrated Heat of Compression) dryer achieves dew points as low as -22°F. The i.HOC uses 100% of the heat generated during the second compression stage for drying, making it effectively available at no additional energy cost. For facilities focused on sustainability, up to 96% of electrical energy input can be recovered as hot air or heated process water, with payback periods of less than a year.

Air-Cooled or Water-Cooled: Choosing the Right Configuration

Kaeser oil-free rotary screw air compressors are available in both configurations. Air-cooled models work where cooling water infrastructure is absent or impractical, are available up to 450 hp, and feature heated exhaust air that can be ducted directly to an adjacent space for heating without auxiliary fans. 

Water-cooled models are the better fit for space-constrained installations: their compact footprint and small exhaust air duct allow placement in smaller, low-ceilinged compressor rooms. For those organizations who require heat recovery for their process, there is no better option than a water-cooled, oil-free screw compressor. Furthermore, the efficiency of the oil-free screw compressor will increase with the water-cooled option. In general, air-cooled versus water-cooled compressors can be summed up in this Kaeser blog post.

Both configurations are available with integrated dryers and SFC variable-speed drive variants. Browse our 50–125 hp and 125–450 hp series pages for full specifications, or shop by horsepower to find your fit. For temporary or mobile needs, the diesel-driven M500-2 MOBILAIR (only available air-cooled) delivers up to 1,600 cfm without fixed infrastructure. For application-specific guidance, visit our compressed air applications page.

 
 

Frequently Asked Questions

What is the difference between an oil-free compressor and an oil-flooded compressor with downstream filtration?

An oil-flooded rotary screw compressor lubricates the compression chamber with oil, which then requires separation and filtration before the air reaches the point of use. Even with high-quality filtration, a small residual oil content remains, typically in the range of 0.01 mg/m³ at Class 1, and filtration efficiency degrades over time as elements age or become saturated. A true oil-free rotary screw air compressor, like Kaeser's CSG, DSG, and FSG series, uses no oil in the compression stage at all. The airend's rotor coating and stainless steel second-stage components maintain a tight sealing clearance without lubrication, so the air leaving the compressor contains no process oil, regardless of filtration condition. In regulated industries, this distinction matters significantly: An oil-free compressor eliminates the risk of a filtration failure that could cause contamination.

How much horsepower do I need for an oil-free rotary screw air compressor?

The right horsepower depends on your required flow rate (measured in cfm), operating pressure (measured in psi or psig), and application duty cycle. Kaeser's oil-free screw compressor line spans 50 hp through 450 hp, covering capacities from 184 to 1,774 cfm at pressures from 60 to 160 psi. For highly variable demand profiles, our SIGMA FREQUENCY CONTROL (SFC) variable speed drive models adjust motor speed to match actual demand, preventing the energy waste that fixed-speed units incur during partial-load operation. A Kaeser system design consultation will identify the right horsepower range and control strategy for your specific load profile.

Can I use an oil-free compressor for food and beverage direct-contact applications?

Yes, this is one of the primary use cases for Kaeser oil-free rotary screw air compressors. In food and beverage operations, compressed air is routinely used for sorting, ejecting, mixing, and packing products, as well as for transporting powdered ingredients and cleaning packaging and molds prior to filling. Kaeser's CSG series features a nanoceramic and PEEK (polyetheretherketone) rotor coating that is food-safe and free of PTFE and silicone, materials that can pose contamination risks in food-contact environments.

Get the Right Oil-Free Compressor for Your Operation

From 50 hp to 450 hp, we engineer Kaeser oil-free rotary screw air compressors to keep your most critical processes running cleanly and efficiently, backed by factory-trained service technicians and a 24-hour emergency parts guarantee. Tell us about your application, your required flow rates, and pressures, and our compressed air system experts will identify the configuration that fits your exact requirements. Request a quote today and put Kaeser's decades of compressed air engineering experience to work for your operation.

Contact KAESER For Your Compressed Air Questions

kaeser compressors representatives help to answer any compressed air questions

Whether you have simple questions regarding your compressed air requirements or require custom solutions, our team is always available to answer your questions.

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