Heavy Duty Air End Design

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Two Stage Oil-Free
Compression Module

The heavy-duty air end design has proven itself consistently since 1955 around the world in demanding applications. This design includes a patented, high-efficiency super rotor profile and cooling jackets. Rotors, shafts and compression housing have a PTFE coating for corrosion and wear resistance.

Precision Machined Castings

Thrust balance pistons on each stage provide maximum air end life. The stainless steel, non wearing air and oil seals with dual vents to atmosphere, assure oil-free air. These features are not found on competitive models. Competitors use carbon rings with single vents and no thrust balance.

Vacuum Degassed Bearings

Compressor Control and Monitoring

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.

Allen Bradley CompactLogix Series PLC

Universal Module for communication with facility management system. Typical protocols include Modbus and BACNet.

HMI Terminal Pressure Page

HMI Terminal
Temperature Page

IO link smart pressure sensors

Pressure & Temperature Smart Sensors

IO link wires

State of the art IO-Link Communication

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.

Oil Circuit

Independent Motor-Driven Oil Pump

Leak-Free Fittings on Oil Circuit Leak-Free Fittings on Oil Circuit

Oil Filter with Differential Indicator

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.

Two Stage Oil-Free Rotary Screw Air Compressors

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.

VFD Control

VFD control provides a narrow system pressure band, reduces inrush at start-up, and allows more frequent stops and starts. VFD control becomes less energy efficient compared to fixed speed when operated at the upper end of speed range.

Load vs. Unloaded Power Consumption

Fixed Speed vs. VFD Power Consumption

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.

Copper tubes with internal turbulators

Removable Tube Bundle

Standard air cooled heat exchangers

Heavy Duty Inlet Air Filter with Pre-Filter

The inlet air filter is easily accessible and includes a cleanable prefilter which extends element life. The air filter is rated at 5 microns and is 99% efficient. A filter change notice is indicated on the HMI.

Air Filter Element with pre-filter

Air, Oil and Water Flow Circuits

Heavy-Duty, Corrosion-Resistant Finish

All Kobelco KNW Series compressors are protected by a unique powder coating system. The powder coating is applied to the base, frame and enclosure. This finish is chip and corrosion resistant and keeps the compressor looking new throughout its lifetime. Other finishes are available for extreme environments.