• Design and operation principle for an oil-injected screw compressor


    1) Air filter
    2) Screw air end
    3) Oil separator
    4) Separator insert
    5) Minimum pressure valve
    6) Oil filter
    7) Thermostat valve
    8) Oil cooler
    9) Air cooler
    10) Oil suction line

    Ambient air is sucked through the filter 1 and then it flows through the suction regulator fitted with a control valve that attunes to instantaneous demand for compressed air. The suction regulator operation is controlled by an electrical unit connected to the pressure transmitter.

    Oil previously treated in the filter 6 is injected into the air compressed in the screw air end 2. The oil injection ensures lubrication, sealing and cooling of the screw air end.

    The oil and air mixture is compressed in spaces between the screw impellers and then flows into the oil separator tank 3 where most of the oil is precipitated from the mixture. From the separator tank the air flows through the fine filter 4, minimum pressure valve 5 and to the aftercooler 9, where it is cooled to a temperature 10°C above the ambient temperature. The oil collected in the oil separator is carried away with the pipe to the screw air end.

    The oil flow through the cooler 9 is controlled by the thermostat 7. The suction and oil filters are fitted with pollution sensors.

    Construction of screw air end

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    1. Drive shaft
    2. Impeller with external teeth
    3. Impeller with internal teeth
    4. Bearing cap
    5. Shaft sealing
    6. Bearings