Screw type liquid ring pump including a pump housing (9) with an inlet part (3) and an outlet part (11) and rotating helical screw rotor (8) inside the housing. The rotor is connected with a shaft (7) as well as a driving unit in the form of motor, preferably an electric motor (2), whereby the pump (20) with the pump housing (9) represents an elongation of the motor (2) with the motor housing thus representing an integrated or one piece unit. The shaft seal (22, 23) is provided wholly or partially in an annular space (24) provided within the rotor (8), whereby one end of the seal rests against an annular part (25) of the screw rotor provided in the annular space (24) between the rotor and the shaft, and its other end is tightly engaged against an inwardly protruding part (21) at the outlet end of the pump.