A device for cleaning of crankcase gas including a centrifugal separator having a housing and a separation chamber in which a rotor is arranged. The separator is connected to a gas inlet for conducting crankcase gas from the crankcase to the centrifugal separator and a gas outlet for conducting the cleaned gas from the separator. A motor is arranged to rotate the centrifugal rotor. A sensor is provided for detection of a parameter and is arranged to communicate with the control equipment. The control equipment is operatively connected to a valve for adjusting the flow of gas through the centrifugal separator. The control equipment is arranged to change the position of the valve in response to a detected change of the parameter such that the gas pressure in the crankcase is maintained at a predetermined value.