Oil-free Compressors

High-quality products require advanced manufacturing technologies, in which high-quality compressed air plays a critical role in the production process. Oil contamination in compressed air can directly affect product quality. Oil-free screw air compressors deliver clean, high-purity compressed air, meeting the stringent requirements of industries such as food, medical, and electronics.

The Kobelco Emeraude series oil-free screw air compressors inherit over 100 years of KOBELCO’s research and development expertise, delivering 100% oil-free compressed air in full compliance with ISO Class 0 standards.

  • 100% Oil-Free Compressed Air 

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Kobelco employs proprietary compressor design and manufacturing technologies to produce 100% oil-free compressed air.
The stainless steel sealing rings completely eliminate the generation of carbon particles.

  • Dual Venting Technology (Patented by KOBELCO)

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The dual venting technology patented by KOBELCO completely prevents oil from entering the compression chamber through the sealing rings, even when the compressor operates under no-load conditions for extended periods.

  • Japanese Screw Manufacturing Technology

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The Emeraude oil-free screw air compressor series incorporates KOBELCO’s latest screw rotor manufacturing technology, produced in Japan, ensuring the highest levels of quality and durability.

  • High-Efficiency Two-Stage Compression Chamber

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Two-stage compression technology reduces power consumption, improves cooling performance, and minimizes pressure drop. Overall operating efficiency is improved by 5–10%.

Operating Principle of Oil-Free Screw Air Compressors

An oil-free air compressor is defined as a compressor in which no oil is present in the compressed air. In other words, oil does not participate in the compression process and does not enter the compression chamber.

In oil-free screw air compressors, the clearance between the screw rotors is manufactured with extremely high precision, keeping reverse air leakage within the compression chamber to a minimum. As a result, no oil is required to seal the rotor clearances, unlike oil-flooded (oil-injected) screw compressors.

However, the compression pressure ratio is limited due to the temperature difference between the inlet and outlet air within the compression chamber. Therefore, oil-free compressors are typically designed with multiple compression stages, most commonly two compression chambers, with intercoolers installed between the stages.

The drive gears are powered and lubricated in a separate compartment, with effective measures in place to prevent oil from entering the compression chamber. Consequently, the compressed air produced is completely oil-free.

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Basic Air Flow Process in an Oil-Free Air Compressor

  1. Ambient air is drawn in through the suction filter.
  2. The air then passes through the capacity control valve.
  3. It enters the first-stage compression chamber (1st stage), where the air pressure is increased to an intermediate level (not yet reaching the final required pressure).
  4. After first-stage compression, the air temperature rises significantly and is then cooled by passing through the intercooler, where the compressed air is cooled and a portion of moisture is removed.
  5. The cooled air subsequently enters the second-stage compression chamber (2nd stage), where it is compressed from the intermediate pressure to the desired final pressure.
  6. The compressed air then passes through a silencer and enters the aftercooler for final cooling.
  7. Finally, the cooled compressed air exits the compressor and is supplied to downstream equipment within the system.

Applications of Oil-Free Screw Air Compressors

Oil-free screw air compressors are widely used in industries where products are highly sensitive to oil contamination, such as semiconductors, pharmaceuticals, food processing, and paper manufacturing. Even a very small amount of oil can significantly affect product quality or indirectly impact end users.

In addition, oil-free air compressors help ensure consistently high product quality. Below are some typical applications of oil-free air compressors:

  1. Automotive Industry: High-quality painting results, smooth production processes, and improved workplace safety for operators.
  2. Food & Beverage Industry: Health-safe operation, consistent product quality, and better taste preservation.
  3. Chemical Industry: Increased product purity, improved process control, reduced waste, and enhanced operational safety.
  4. Electronics Industry: Uninterrupted control systems and maintenance of ultra-clean environments for high-quality products.
  5. Textile Industry: More efficient production, reduced repair and maintenance costs, improved fabric quality, and minimized waste.
  6. Pharmaceutical Industry: High-purity products, reduced contamination risks, more efficient processes, and lower waste generation.