A method cleans a plurality of filters in parallel, each a filter having an inlet side and an outlet side separated by a filter barrier. The interface circuitry comprises buffer circuitry coupled between the operational circuitry and the data storage circuitry which is arranged to store data access requests received from the operational circuitry and to store data retrieved from the data storage circuitry. A seal gas is introduced between the outer circumferential surfaces of the bearing members and the inner circumferential surfaces of the rotor cylinders of the screw rotors through the bearing members.