Abstract: A method for determining the fatigue of the pump rotor of a gas turbopump comprises the following method steps: continuous determination of the rotational speed (n) of the pump rotor, determination of the local rotational speed maxima and minima of a temporal rotational speed profile under consideration, association of the rotational speed maxima and minima with each other to form pairs, determination of a pair fatigue value (L) for each of the rotational speed pairs, and accumulation of all pair fatigue values (L) to form a total fatigue value (Ltot). In this manner it is possible to determine the cyclic stress for the pump rotor of a vacuum pump and to include it in the calculation of a total fatigue value.

Abstract: An overall leakage rate of a vacuum system which can be operated continuously or cyclically is determined. The vacuum system includes at least one process chamber (10) and a pumping device (16) connected to the process chamber (10). In a cyclical leakage rate determination technique, the following steps are taken: suppressing a process gas feed to the process chamber (10), feeding a carrier gas to the process chamber (10), conveying the carrier gas and a leakage gas using the pumping device (16), measuring an amount of a gas component in the pumped gas, and determining the overall leakage rate of the vacuum system based on the measured amount of the gas component.

Abstract: A method for determining the fatigue of the pump rotor of a gas turbopump comprises the following method steps: continuous determination of the rotational speed (n) of the pump rotor, determination of the local rotational speed maxima and minima of a temporal rotational speed profile under consideration, association of the rotational speed maxima and minima with each other to form pairs, determination of a pair fatigue value (L) for each of the rotational speed pairs, and accumulation of all pair fatigue values (L) to form a total fatigue value (Ltot). In this manner it is possible to determine the cyclic stress for the pump rotor of a vacuum pump and to include it in the calculation of a total fatigue value.

Abstract: A friction vacuum pump for use in a system for regulating the pressure in a vacuum chamber includes a multistage turbomolecular vacuum pump section (6) whose stages each consist of a row of stator vanes and rotor vanes (14 or 13). The pump regulates the pressure of heavy gases or of a gas mixture containing heavy gases. To this end, the friction vacuum pump (1) is equipped with a molecular pump section (11) located on the fore-vacuum side and a space (21, 22, 23), in which the pump action is interrupted. The space is provided in the transition area from the turbomolecular vacuum pump section (6) to the molecular pump section (11) or in the transition area from the molecular flow to viscous flow.

Abstract: During the pumping of corrosive gases, it is advantageous to admit a seal gas to endangered pumping chambers at a lower flow rate and a higher pressure than the corrosive gases. Inert gas from a supply (3) has its pressure reduced by a pressure reducer (6). An on/off valve (7) controls a flow of the inert gas through a flow restriction (8) which restricts the flow of inert gas to appropriate sealing gas rates at an outlet (4). After pumping the corrosive gas, a control valve (12) in a bypass line (11) causes the inert gas to be supplied to the outlet (4) at a higher flow rate for purging the pump.