A rotary screw vacuum pump system includes a vacuum bypass system, which communicates with a first closed cell formed by the rotor system. An air bypass valve within an air communication conduit is controlled by a solenoid valve that operates in response to a pressure switch. The pressure switch is in communication with a vacuum pump suction conduit that draws suction for a suction system attached thereto. The solenoid valve is activated by the pressure switch at a vacuum level slightly below the point at which the undesirable cavitation noise generated at terminal vacuum condition begins.