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Kobelco KNW Series
Oil-Free Rotary Screw Air Compressors
Heavy Duty, Two-Stage Air End Design
40-500 Horsepower / 172 - 2400 ACFM
Heavy duty oil-free compression module, the heart of the compressor’s reliability and performance
Proven Technology
Over 65 years of field experience in all industries has proven that KOBELCO KNW Series rotary screw design is the preferred choice for reliability, energy efficiency and serviceability
Two-Stage Design
Heavy duty, two-stage compression module with thrust balancing for long bearing life in each stage. Designed, tested and manufactured in the USA. No other oil-free compressor manufacturer has made that commitment to the North American market. Also available as single stage design for low pressure applications
Coated Rotors
ASTM 1144 steel rotors with exclusive PTFE coating on rotors and shafts for maximum efficiency and corrosion protection. Gears and bearings are lubricated by a unique motor driven oil pump that provides positive lubrication prior to start-up, through operation and after shutdown. This is an especially important feature for VFD models and not available on competitive offerings.
Unique Design Features
Key design features ensure long air end life. All features may not be available on competitive models.
Features Include:
Non contact maintenance free air and oil seals
Thrust balance compensation
Cooling jackets
Dual vents to atmosphere ensure oil-free air
Vacuum degassed thrust and radial bearings
Premium AGMA rated gears
All models meet the requirements of NFPA 99 for use as a medical air compressor
Superior Monitoring Systems
The most advanced control and monitoring systems available
The Kobelco KNW Series oil-free rotary screw air compressor uses an Allen Bradley programmable controller to control and monitor compressor operation. Operations include controlled sequential starting and stopping, pressure control, and protection from conditions that could damage the compressor. Pilot lights, viewable from a distance, are provided for indication of operating conditions. An audible alarm is provided for alarm annunciation. Push buttons are provided for specific control functions, allowing continued compressor operation in the event that the terminal is off-line.
The HMI terminal is an LCD graphic display with touch screen. The HMI terminal shows operating conditions, pressures and temperatures. Messages are sent to direct the operator for service, pre-alarms, and alarms, and will be shown when necessary. Required settings for pressure control, temperature alarms, and control time delays are viewable and may be modified using the touch screen. The HMI terminal will automatically “dim” to a sleep condition if inactive, and awakens on any touch contact. A universal communication module is also available to handle virtually any Ethernet or Serial driver. They can be designed according to customer preference. The VFD data, if applicable, including KW, amps, hertz and rpm.
The USB through door port is provided below the HMI. Also included is an SD memory card. Both provide the ability to download data loggers, alarm history, compressor status report, and the daily report from the HMI. These files can then be opened using Microsoft Excel. External memory (USB, SD) provides the ability to update or modify the existing HMI project.
Compressor pressure and temperatures are monitored using smart sensor technology and I/O link communication. Real time pressure and temperature values are displayed on the HMI. Pressure and temperature trends are also on the HMI. All values are also available for remote monitoring. I/O link is specifically designed for communication with smart sensors and allows detailed diagnostics of sensor health.
Pre and Post Lubrication of Gears & Bearings
Unique to Kobelco KNW Series: Lubrication prior to start up, during operation and shutdown is supplied by an independent motor-driven gear pump. The compressor will not operate until oil pressure is established. The design increases gear and bearing life and is not offered on competitive models. All oil-side piping is stainless steel and has SAE leak-free fittings.
Heavy Duty Input Bull Gear Design
The input bull gear is supported on each side. Competitors use an overhung design. The labyrinth type seal used on the drive end ensures leak-free operation. Competitors use a lip seal design, which is prone to wear and leakage. These features found on the Kobelco KNW Series ensure a long operating life and eliminate oil leaks.
Capacity Control: Fixed Speed or VFD
Fixed speed, also known as load-unload, provides energy-efficient operation during loaded and unloaded operation. During unloaded operation, brake horsepower is reduced to approximately 18% of full load. This reduces the overall energy cost significantly. The valve is a positive-closing disc type with orifices, using spring and air pressure to activate. Unloaded horsepower is guaranteed and repeatable. The valve is designed for 1,000,000 load-unload cycles and is easily serviced.
Highly Efficient Cooling System
Kobelco KNW Series water-cooled models feature highly efficient, removable, copper tube bundles. Internal turbulators provide optimum heat transfer with minimal pressure drop. Shells are made of carbon or optional stainless steel with an ASME stamp. Water-cooled models include a thermostatic valve on the intercooler and an automatic shut-off valve on the cooling water inlet. Air is inside of the tubes and water is in the shell.
Air-cooled heat exchangers are made of heavy-duty aluminum with a special coating and are designed for all published operating conditions. Kobelco KNW Series air-cooled models include a thermostatic mixing valve to insure proper oil temperature in changing ambient temperatures.
All water and air-cooled models have oversized moisture separators with automatic drains for maximum efficiency.