About the Kobelco KNW Series

The Kobelco KNW Series assembly is designed and constructed to exacting quality standards. These standards result in assemblies with long operating life, minimum maintenance, and low operating costs.

High Quality, Quiet and Attractive

The Kobelco KNW Series oil-free rotary screw air compressor is designed, manufactured, assembled, and tested in the United States and is delivered ready for operation. The two-stage rotary screw compressor provides completely oil-free air because no oil is allowed in the compression chambers.

Both compression stages employ a new-patented Super Rotor design, which is acknowledged to be the most efficient, two-stage, oil-free rotary screw air compressor on the market. This new asymmetric rotor profile provides the lowest power consumption per cubic foot of compressed air.

The efficiency is further enhanced by a unique load/unload control system that is simple and trouble free.

The compressor air-end is a heavy-duty, two-stage design with each stage driven by a common gear. These components are arranged in a single modular design to form a compact unit which is mounted on vibration isolators to a structural steel base. No special foundation considerations are required.

 

Simple and Efficient with High Reliability

Precision machined timing gears are mounted on each rotor shaft to maintain accurate clearances between the rotors. The bearings are anti-friction type for long life and smooth operation. The electric motor is directly coupled to the input drive shaft through a flexible coupling.

Axial thrust is reduced by incorporating an air pressure operated thrust balance piston on each stage. This arrangement minimizes thrust loading thus increasing bearing life.

The state-of-the-art programmable microprocessor controller maximizes operating efficiency and versatility.  Kobelco’s sound attenuated enclosure assures quiet operation. Doors are hinged and pinned allowing easy removal for inspection and maintenance.

Design Features

High Efficiency Rotors

The new patented Super Rotor profile is the most efficient in the industry. The machined forged steel rotor sets have the most precise tolerances in the industry. FDA approved rotor coating further increases volumetric efficiency. In addition, the new profile provides 20% more displacement per revolution thus lowering rotor speeds and increasing bearing life.

Dual Vent Seals with Stainless Steel Rings

Each shaft seal consists of floating stainless steel rings and an oil labyrinth inserted between the rotor chamber and the bearings. Each seal is buffered by gas from the compression chamber which is purged to atmosphere ensuring that no lubricating oil or its vapor can enter the compression chamber.

Lubrication of Gears and Bearings

Lubrication prior to start-up, during operation and after shutdown is supplied by an independent motor driving gear pump. Compressor operation is not allowed until oil pressure is established. During the coast down period the oil pump continues to provide full lubrication until the compressor stops. This design increases gear and bearing life and is not standard on competitive units.

Capacity Control Valve

The efficient and simple capacity control system is a load/unload type with a direct operating disc valve and no discharge air recalculation. During unloading the bleed-off air is released to atmosphere through a muffler. This eliminates the need for a bleed-off cooler and the associated problem of condensed moisture entering the inlet of the compressor. The control is an electro-pneumatic device. No oil, hydraulic cylinders, or rolling diaphragms are used in the operation of this valve.

Load and Unload Control

This control provides energy efficient operation while eliminating adjustments and minimizing maintenance. When the compressor unloads the brake horsepower drops to approximately 18% of full load, significantly reducing overall energy cost. The compressor will shut down after operating unloaded for a period of time and will automatically restart on pressure demand.

Operator Interface / PLC

 

 

Operator Interface and PLC

 

The Kobelco KNW Series Oil-Free Rotary Screw Air Compressor uses an Allen-Bradley Programmable Logic Controller (PLC) to control and monitor compressor operations.

 

Graphics touch screen display

Sunlight readable grayscale or color

Event alarm log

Pre-alarm warnings

Panel adjustable set points - temperature and pressure

Password security

Real time clock

Alternate temperature units - degree F. or degree C.

Continuous temperature displays

Maintenance reminders

Configurable graphs for trending

Ethernet option

Connection to DCS, FMS or Scada by network or modem

Installation and Start-Up Supervision

A factory trained field representative will supervise installation and start-up. This same representative will also train your maintenance personnel in the operation and maintenance of the assembly. Our commitment is to provide a trouble free, reliable installation of which we can both be proud.

Factory Monitored Maintenance Program

Compressor performance parameters are recorded by the customer on factory-supplied forms and then examined monthly by factory experts at no charge.

Controls and Instrumentation

Service Indicators

Air inlet filter condition indicator

Oil filter condition indicator

Oil level gauge

Routine maintenance

Pressure Indicators

First stage air discharge pressure gauge

Second stage air discharge pressure gauge

Oil pressure gauge

Temperature Indicators

First stage air discharge

Second stage air inlet

Second stage air discharge

Lube oil

Additional Indicators

Stand-by mode light

Oil pump run light

Fan run light

Compressor run light

Compressor load light

Alarm light

Hour meter - running time

Hour meter - load time

Manual unload light and switch

Safety Devices

All safety shutdowns are indicated by message on display and alarm light.

Compressor motor overload shutdown and light

Oil pump motor overload shutdown and light

Fan motor overload shutdown and light

High first stage air discharge temperature shutdown and light

High second stage suction temperature shutdown and light

High second stage air discharge temperature shutdown and light

High oil temperature shutdown and light

Low oil pressure shutdown and light

High cabinet temperature shutdown and light

Starter failure light

Temperature pre-shutdown alarm

Additional Devices

Start/stop push buttons

Lamp test

Audible alarm

Acknowledge switch

Reset Switch

Common alarm contracts for remote indication

RS485 network connection for DCS/FMS systems

Additional Features

Packaged Assembly

Air-cooled or water-cooled

Integral air-cooled or water-cooled aftercooler with moisture separator and automatic drain

Cabinet ventilating fan

Easy access for maintenance

Removable hinged doors

Low installation cost

Few connections required for installation - compressed air, condensate drains, electrical and water (when required)

Control settings easily accessible

Full voltage motor starter (460 volt standard)

CSA certified panel

Advanced Design

Super Rotor delivers more cfm per horsepower

Efficient Control

Load/Unload electro-pneumatic

Vibration Free

No vibration generated in smooth rotary design

No special foundation required

Low Water Usage (water-cooled units)

Cooler selection is optimized to reduce cooling water requirements

Automatic intercooler water regulating valve standard equipment

Options

Single-stage design

Duty sequencers for multiple compressor installations

All types of reduced voltage starters

Extended warranty programs

Outdoor weather protection

Freeze protection

Non-standard motors

Variable Speed Drive