| 摘要 |
The invention concerns a vacuum pump system with a Roots vacuum pump (4), which can be connected to a vessel (1) to be evacuated by way of a first valve (2), and which is also connected to a backing pump (5). In the invention, a second pump array (6, 7) is provided, which can be connected to the vessel to be evacuated by way of a second valve (3), with means (10) being provided to control the valves, such that the first valve (2) is opened and simultaneously the second valve (3) is closed when the pressure in the vessel drops below a preset value. Such a pump system prevents flooding of the Roots pump's (4) oil chambers through the vessel (1), and reduces the time taken to reach the desired final pressure in the vessel substantially. <IMAGE>
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