Oil Free Air Compressors: Best Choice for Pure Air
Two Stage Oil-Free Rotary Screw Compressors
Fixed and regulated speed rotary screw air compressors
The launch of this brand-new range of oil-free screw compressors offers the lowest total cost of ownership on the market, with up to 8% higher flow rates, up to 7% energy reduction and guaranteed air purity. These high output oil-free machines now cover a wide flow range from 14.6 to 28.3 m³/min. The DX90 to DX160 models are fixed speed and the DX90RS to DX160RS models are regulated speed.
Pressure range: 4 to 10.7 bar
Volume flow: Capacity of 6.7 to 28.3 m³/min
Motor power: 90 to 160 kW
CompAir has extended its proven range of DX, oil-free rotary screw air compressors with the launch of the new DX90-160 (RS) series, offering up to 14 per cent improvement in energy efficiency and up to eight per cent higher flow compared to industry standards. The range has been designed to offer best-in-class energy performance, excellent reliability and reduced lifecycle costs - in an oil-free compressor which is Class Zero certified according to ISO 8573-1:2010. This means there is virtually no risk of contamination in the production process, making it ideal for applications where high levels of air purity are essential. The new range includes fixed and variable-speed models from 90 to 160 kW.
David Bruchof, Oil-Free Product Manager, said: “Capable of delivering pressure ranges from 4 to 10.7 bar and volume flow between 6.7 to 28.3 m³/min, our new series is the latest enhancement to our proven range of two-stage, oil-free rotary compressors and has been designed to prioritise efficiency at every stage. From the completely redesigned air end to the unparalleled energy efficiency improvements of the whole compressor package, this new series will deliver substantial energy savings, with the lowest cost of ownership for rapid return on investment.”
Oil-free air compressors are designed to deliver 100% clean, contamination-free compressed air—making them the preferred choice for industries where air purity is critical.
No oil in the compression chamber → eliminates risk of oil contamination
Achieves ISO 8573-1 Class 0 air quality (highest purity level)
Ideal for:
Food & beverage processing
Pharmaceuticals & medical use
Electronics & semiconductor manufacturing
👉 Unlike oil-injected systems, which can still allow trace oil carryover, oil-free compressors ensure zero contamination risk
🔹 Key Benefits
✅ Pure air output (no oil mixing)
✅ Lower maintenance (no oil changes)
✅ Product safety and compliance
✅ Reduced risk of equipment damage
Two-Stage Oil-Free Rotary Screw Compressors
These are among the most advanced and efficient oil-free compressor designs.
🔧 How They Work
A rotary screw compressor uses two interlocking rotors to compress air. In oil-free designs:
Rotors don’t touch and require high precision engineering
No oil is used for sealing or cooling inside the compression chamber
⚙️ Two-Stage Compression Explained
Instead of compressing air in one step, the process happens in two stages:
Stage 1: Air is compressed partially
Intercooler: Air is cooled to reduce heat and improve efficiency
Stage 2: Air is compressed to final pressure
This staged process:
Improves efficiency
Controls temperature
Enables higher pressure without oil lubrication
🚀 Advantages of Two-Stage Oil-Free Rotary Screw Compressors
1. Superior Air Purity
Delivers oil-free air with zero contamination risk
Meets strict industrial standards (Class 0)
2. Higher Efficiency
Interstage cooling reduces energy consumption
Work is split across two stages → better performance
3. Reliability & Consistency
Continuous-duty operation
Stable airflow and pressure
4. Lower Operating Costs (Long-Term)
No oil replacement or filtration costs
Reduced maintenance downtime
⚠️ Things to Consider
Higher initial investment compared to oil-injected compressors
Slightly lower pressure per stage, requiring multi-stage design
Advanced engineering → higher precision components
🏭 Where They Are Used
Two-stage oil-free rotary screw compressors are widely used in:
Pharmaceuticals & hospitals
Food and beverage plants
Electronics manufacturing
Textile and clean-room environments
✅ Conclusion
If your application demands clean, reliable, and contamination-free compressed air, oil-free compressors—especially two-stage oil-free rotary screw compressors—are the best choice.
They combine:
Maximum air purity
Energy-efficient operation
Industrial-grade reliability
