Abstract: A two-stage rotary vane vacuum pump includes a pre-vacuum stage having a pre-vacuum pumping chamber and an outlet valve; a main oil sump; and a first oil conduit having a first opening communicating with the main oil sump and a second opening communicating with the pre-vacuum pumping chamber. The first opening is located at a level below an operational oil level in the main oil sump. There is further provided an intermediate oil sump situated at a level above the outlet valve and being arranged for receiving oil from the pre-vacuum pumping chamber; and a second oil conduit leading from the intermediate oil sump to components of the vacuum pump to be supplied with oil. All such components are situated at a level below the intermediate oil sump.

Abstract: A rotary vane vacuum pump includes a pump housing; a bearing support having a bearing bore; a drive motor having an output shaft extending into the bearing bore; and a pump rotor accommodated in the pump housing and having a rotor shaft extending into the bearing bore. The rotor shaft and the output shaft have respective radial end faces oriented towards one another and the output shaft and the rotor shaft have identical diameters. There is further provided a torque-transmitting coupling connecting the output shaft with the rotor shaft at respective radial end faces thereof; a first sealing ring situated in the bore and sealingly surrounding the output shaft; a second sealing ring situated in the bore and sealingly surrounding the rotor shaft; and a lubricant chamber formed by a part of the bearing bore and being bounded and sealed by the first and second sealing rings.

Abstract: A method and apparatus for delivering oil into a pump chamber of a high-vacuum stage of a multi-stage pump. The method includes the steps of sensing a first pressure at an intake region of the high-vacuum stage of the pump, and sensing a second pressure at a discharge region of the high-vacuum stage of the pump. Oil is delivered to the high-vacuum stage of the pump in response to a pressure difference between the first and second pressures. Increased quantities of oil are delivered to the high-vacuum stage of the pump when the pressure difference exceeds a predetermined value. A gas ballast may also be delivered to the high-vacuum stage of the pump when the pressure difference exceeds this predetermined value. The apparatus may include a diaphragm valve including a diaphragm mounted between subchambers that are respectively in fluid communication with the intake and discharge regions of the high-vacuum stage of the pump.

Abstract: A vacuum pump and trap combination in which the trap is configured in the manner of a siphon and comprises a tube immersed in trap liquid but having an opening lying above the trap liquid level. The tube has a wall section lying below the trap liquid level and having perforations therein to admit different amounts of trap liquid in relation to the rate of discharge gas flow, thereby preventing frothing of the trap liquid.