Oil Free Air End OGW Series
- Discharge Pressure: 3-40 [bar], 43-580 [psig]
- Free Air Delivery: 0.9-60.0 [m³/min], 32-2119 [cfm]
- Available in Single Stage and Two Stage
- Applicable Compressor Type: Water Lubricated Oil Free Compressor
Gairs’ air ends, designed for water-injected oil-free screw compressors, leverage decades of expertise in single screw technology to deliver exceptional performance. Engineered for durability and efficiency, they cater to a wide range of applications, providing reliable, oil-free compressed air with minimal maintenance and maximum operational lifespan.
- Features
- Technical Specifications
- Schematic Diagram
- Downloads
- Durable and Long-Lasting Performance: Constructed with stainless steel housing, screw rotor, and star wheel pieces made from highly wear-resistant Polyether Ether Ketone (PEEK), ensuring exceptional durability and longevity.
- Low Noise and Vibration: Advanced bilateral symmetry design, featuring a centrally positioned screw rotor with star wheels on both sides, effectively minimizing radial and axial forces, resulting in reduced noise and vibration.
- Unmatched Efficiency: The use of water as a lubricating, sealing, and cooling medium provides superior dynamic lubrication performance at low speeds (3000 RPM), ensuring exceptional energy efficiency.
- 100% Oil-Free Compression: Featuring water-based lubrication in the compression system, this compressor delivers 100% oil-free, water-purified air, certified by TUV for air purity.
- Simple Overhaul: Minimal maintenance required—replace a few internal parts to restore your air end to like-new condition.
- Versatile Applications: Offers tailored solutions for both general industrial use and specialized applications that demand 100% air purity.

Unique Design That Maximizes Efficiency
The advantages of the single screw air compressor are embedded in its unique air end design.
The single screw air end consists of a cylindrical screw rotor and two symmetrically placed star wheels within a housing. The working volume is formed by the screw groove, the inner wall of housing, and the star wheel’s teeth. The motor directly drives the screw rotor, which, in turn, rotates the star wheels. Air enters through the suction port and is discharged after compression. A water injection hole in the air end injects lubricating water for sealing, cooling, and lubrication.
Low Vibration and Low Noise
The symmetrical star wheel placement ensures axial and radial forces are perfectly balanced, minimizing stress on the screw.
A key feature of the single screw compressor is its closed high-pressure axial end, which means the axial compressed air force is internal, preventing the screw from bearing any axial force. The symmetrical placement of the star wheels on both sides of the screw results in opposing radial forces that offset each other, achieving complete force balance and ensuring smooth operation.


Extended Service Life Guaranteed
Balanced friction design contributes to exceptional durability and long lifespan of the air end.
Another key feature of the single screw air end is the friction dynamics between the screw groove and the star wheels. The friction force is parallel to the atmospheric force acting on the star wheels, preventing the atmospheric force from affecting the friction. This unique design is crucial for establishing dynamic lubrication, which is the main factor behind the star wheel’s long service life.
Frequently Asked Questions
The following are frequently asked by our customers about Air end for oil free screw compressor.
The water used for lubrication, sealing, and cooling must be RO (Reverse Osmosis) water to ensure optimal performance and prevent damage to the air end.
The compressed air temperature should not exceed 50°C to maintain the efficiency and longevity of the air end.
No, you do not need to replace the entire air end. Only specific parts such as the star wheels, bearings, and mechanical seals need to be replaced, making it a more economical solution.
Air end at first stage is recommended after 3 years (or longer) or 18,000 running hours. The second stage is after 2 years or 12,000 running hours. Overhauling involves replacing parts like star wheels, bearings, and mechanical seals, rather than replacing the entire air end.
Yes, for clients in remote locations, we recommend purchasing extra air ends. If you’re unable to perform an overhaul on-site, you can use the spare air end and ship the old one to us for servicing. This ensures minimal downtime and maintains the operational efficiency of your compressor.