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1) Air filter
2) drive motor
3) 1stcompression stage
4) 2ndcompression stage
5) Oil tank
6) Oil pump
7) Oil pressure regulator
8) Thermostatic valve
9) Oil filter
10) Oil divider
11) Oil cooler
12) Aftercooler
13) Intercooler
14) Suction regulator
15) Second degree relief valve
16) Silencer
17) Venturi tube
18) Water separator
19) Fan

Design and operation principle for an oil-free screw compressor

After being drawn in by the dry suction filter 1, ambient air passes through the resonance silencer and suction regulator 14 fitted with an infinitely variable control valve that operates according to instantaneous demand for compressed air. The air regulator is controlled via an electrical system integrated with the controller.

Pre-compressed within the first compression stage 3, air passes through the Venturi tube 17.The tube’s role is to reduce the noise and pressure fluctuations. Next, air enters into the intercooler 13 where it is cooled. After leaving the intercooler, it passes through the water (cyclone) separator 18 which removes water from the air. Then, air is pressurised up to the set point required by the second compression stage 4. Compressed air passes through the Venturi tube to the aftercooler 12 and then through the water separator and non-return valve to the compressed air network.
The two compression stages are protected against excessive pressure with safety valves.

Oil, drawn in by the oil pump 6 from the oil tank 5 integrated with the screw air end, flows into the oil pressure regulator 7 where it reaches the required pressure. It then flows through the thermostatic valve 8 and oil cooler 11 into the oil filter 9. The oil divider 10 controls the volume delivered to bearings, toothed gears, cooling jacket (in selected models) and screw stage suction regulator. Finally, oil flows back into the oil tank.

Oil circulates in a closed circuit that is ultimately safe and independent of the compressed air circulation.