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Oil-free Screw Air Compressor 3-4 Bar

The OGWBD water-injected screw compressors are designed to provide oil-free air, making them ideal for applications that require both reliability and purity. This low pressure air compressor was specifically developed to meet the demands of users in industries such as glass bottling, fermentation and textiles.

Single Stage Variable Speed Water Injected Oil-Free Screw Compressor Model: OGWBD

  • Discharge Pressure: 3-4 [bar], 43-58 [psig]
  • Free Air Delivery: 3.0-60.0 [m³/min], 106-2119[cfm]
  • Rated Motor Power: 11-200 [kW], 15-268 [hp]

100% Oil-Free Operation
The compressor uses water for lubrication instead of oil, ensuring 100% clean and pure compressed air that meets ISO 8573-1 (2010) and TÜV CLASS ZERO standards.

High Efficiency

  • Single-Screw Technology: Eliminates clearance volume, improving performance.
  • Water Lubrication: Seals gaps in the compression chamber, allowing for high efficiency even at temperatures close to 50°C.
  • Near Isothermal Compression: Uses water as a cooling medium to maintain constant air temperature throughout compression, reducing energy consumption.

Low Noise

  • Quiet Design: Single screw airend utilizes a stainless steel screw rotor and polymer-made star wheels for meshing components.
  • Direct Coupling: Features a direct coupling between the motor and the screw, minimizing vibration and noise.
  • Sound Insulation: The enclosure is lined with sound-absorbing material to effectively reduce noise levels.

Energy Saving

  • VSD+PM Motor: Variable speed drive combined with a permanent magnet motor for exceptional energy efficiency and savings.

Stable Air Delivery

  • Dynamic Pressure Control: The controller continuously monitors discharge pressure using the compressor’s pressure sensor and adjusts the inverter’s output frequency to regulate motor speed and ensure stable free air delivery.

Robust Components

  • Stainless Steel 304: All piping and key components, including the airend (rotor and housing) that come into contact with air and water, are constructed from durable Stainless Steel 304. This ensures long-lasting performance and resistance to corrosion.

OGWBD Model Configuration

Gairs Airend

  • Stainless steel 304 rotor & housing
  • Star wheel pieces material: PEEK (polyether ether ketone)
  • Speed of Revolution: 3000 rpm

Permanent Magnet Motor

  • Motor Enclosure Protection: IP55
  • Energy Efficiency Class: IE5
  • Direct coupling

Inverter & PLC controller

  • Brand: Inovance
  • Language: Chinese, English, Korean, Russian

Centrifugal Fan (air-cooled unit)

  • Enhanced cooling efficiency
  • Reduced noise levels

Electrics

  • AC Contactor brand: Schneider

Parts & Valves

  • Water softener brand: Pentair
  • Normally open/closed solenoid valves: SMC

In-House Airend Production

Since 1988, Gairs has specialized in single screw technology. In a single screw airend, the screw rotor is made from stainless steel to maximize wear and corrosion resistance, while the star wheel pieces use polyether ether ketone (PEEK), a high-performance polymer known for outstanding mechanical and chemical durability, even under high temperatures.

Low Maintenance Cost

The key advantage of purchasing a Gairs compressor is the exceptionally low maintenance cost. For routine upkeep (excluding airend overhaul), you simply need to replace the air filter element, water filter element, and water softener element—a process that takes only about 30 minutes.

low maintenance cost 570x360

Example Comparison

OGWBD Low Pressure Screw Compressor Other Similar Low Pressure
Compressor
Motor power 132kW
Free Air Delivery Volume/Pressure 45m3/min/0.3MPa 40m3/min/0.3MPa
1 Year Energy Saving 15kW/hour*24hours*365days*$0.15=±$19,700

Frequently Asked Questions

The following are frequently asked by our customers about OGW series water lubricated oil-free air compressors.

What's the requirement for the lubricating water used in the Gairs compressor?

Reverse osmosis (RO) water must be used as the lubricating water source.
In our Gairs OGW series of water-lubricated compressors, lubricating water is injected into the airend to facilitate cooling. Inside the airend, the water acts as a seal between the star wheel and the screw rotor, enhancing the compressor’s volumetric efficiency. Since the lubricating water continuously circulates within the system, its quality directly impacts the airend’s lifespan.

What's the advantages of water-injected oil free air compressors?

1. Reduced Maintenance: Water-injected oil free compressors generally have fewer moving parts and less wear, leading to lower maintenance needs.
2. Lower Operating Temperature: They operate at cooler temperatures, reducing the risk of overheating and extending equipment life.
3. Better Efficiency: Water injection helps with cooling and sealing, improving efficiency and energy consumption.
4. Cleaner Air Supply: They produce 100% oil-free compressed air, reducing contamination risks.
5. Quieter Operation: Typically quieter than dry twin screw compressors due to the single screw airend structure.

How often should I replace the filter element?

We suggest replacing the air filter element every 2000 hours of operation, the water filter element every 1000 hours, and the water softener element twice a year.

How often should I maintain the airend?

Maintenance of the airend depends on the compressor’s usage frequency and the working conditions of the compressor room. For single-stage models like OGWY(B) and OGWBD, it is recommended to perform maintenance every 3 to 5 years. For specific inquiries, please contact us directly.

What's the lead time?

Typically, the lead time for a single-stage model is approximately 25-30 working days, while the lead time for a two-stage model is around 40-45 working days.

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