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Hitachi DSP Oilfree Rotary Screw Air Compressors

The DSP Series from Hitachi comes in fixed speed and variable speed versions and covers a 20 to 125 HP range. Hitachi manufactured the first ever oilfree rotary screw compressor in 1968 and continue to pave the way today with the DSP Series.

Air End Design
Hitachi oilfree DSP Design Advantages
Maintenance Friendly
DSP Model Versions Available by HP

Hitachi DSP oilfree air compressors cannot be purchased online at eCompressedair. But, our sales engineers can quickly send you a budgetary quote for any model. And are qualified to work with you to select the correct DSP for your particular need. Delivery is fast. Some models are in stock. Request a quote here.

oilfree Rotary Screw Air Comprssor. Hitachi 100 HP DSP Series Pictured.

Air End Design

Rotors manufactured from SUS403 stainless steel
First and Second stage rotors are stainless steel
Dual lead tooth profile on the male and female rotors
Tapered rotor design compensates for thermal expansion at operating conditions (Hitachi Patent USP 04952125)
No PTFE
A patented (Japan P3740178) HX-18 coating is applied to the rotors at a uniform thickness
HX-18 coating handles high operating temperatures
Superior solid film lubricating performance

Hitachi oilfree Screw Design Advantages

Hitachi DSP oilfree air compressors cannot be purchased online at eCompressedair. But, our sales engineers can quickly send you a budgetary quote for any model and are qualified to work with you to select the correct DSP for your particular need. Delivery is fast. Some models are in stock. Request a quote here.

Hitachi's DSP Series has several design advantages compared to its competitor's oilfree rotary screws. Hitachi's advantages:

Hi-Precooler

Hitachi's patented Hi-Precooler is a stainless steel heat exchanger that removes heat of compression reducing the load on the aftercooler (Patent USP 04929161). Located between the airend and the checkvalve before the aftercooler the Hi-Precooler...

Cools the compressed air that is purged to atmoshere during unload operation
Protects the check valve from high temperature compressed air discharged from the airend
Cools hot compressed air prior to the aftercooler

Oil Mist Remover

Hitachi's patented Oil Mist Remover (OMR) 99.99% efficient oil remover stops oil vapor from venting to atmoshere (Patent USP 05011388). Putting the vent oil back in the gear case keeps the compressor room clean. Plus, the frequency oil has to be added is reduced. This reduction saves labor hours and maintenance dollars spent on replacement oil.

How does Hitachi's OMR work? The OMR has an ejector that uses compressed air to generate vacuum pressure against the OMR system and gear case. This prevents the gear case's internal pressure from rising from resistance from the oil remover element.

Quiet Operation and Small Footprint

Hitachi strives to make DSP compressors the quietest oilfree screws available. To make them quiet Hitachi provides:

Full enclosure as standard
Mechanical and electrical vibration isolation
Design to minimize leak paths
Unit is compact in overall dimensions
Panel access helps space conservation

Microprocessor Controller

Hitachi's standard controller saves energy compared to conventional controllers by keeping system pressure stable in a narrow pressure band.

Narrow pressure band operation
Variable speed design units quickly adapt to variation in demand
Lead/Lag (2 units) is standard
Instantaneous Power Interruption (IPI) restart is standard

Controller's LCD Panel Indication:

Current
Active capacity control type
Discharge air pressure
Oil/Coolant pressure
Accumulated operating hours
Temperatures of Oil/Coolant etc
Date and remaining operating hours until next maintenance
Actual demand percentage compared to full load capacity

Compressor functions available on the standard controller:

Instantaneous Power Interruption restart
Automatic motor on-off
Remote operation dry contacts
Lead-Lag operation
Dryer pre-start dry contact

Matched Motor & Drive

Inverter drive (VSD Models)
EPAct motors
UL listing
TEFC construction

DSP-Vplus and Vtype No Inlet Valve Design

Advantages of Hitachi's patented no inlet valve design... Hitachi No Inlet Valve Design Drawing

No vacuum is generated at airend inlet and succeeded to obtain stable sealing performance even at slow running speed
No parts replacement is necessary in inlet valve
No temperature rise at capacity control as no vacuum exist at the inlet

The No-inlet valve design is patented by Hitachi. No-inlet valve design patent number is US6461112 B1 and the no-inlet valve design with interstage purging patent number is US6739841 B2.

Maintenance Friendly

The DSP compressor allows easy access to regular maintenance items like filters and for easy visual inspection of the compressor.
Hitachi Easy to Maintain DSP Compressor

DSP Series Oilfree Rotary Screw Air Compressor Versions Available by Horse Power

Discharge Pressure 100 psig for Single stage models.

Discharge pressure 100 or 125 psig available for Two stage models.

Better Business Bureau Reliability Program Seal