| 摘要 |
PROBLEM TO BE SOLVED: To provide an evacuation system that can switch evacuation operation from a vacuum pump to a backup pump before the rotational speed of the vacuum pump greatly decreases.SOLUTION: An evacuation system comprises: a vacuum pump 10 connected to a branch pipe 6; a backup pump 12 connected to a backup pipe 8; and an operation control unit 20 that controls opening/closing operation of an opening/closing valve 15 and a backup valve 16. When the rotational speed of the vacuum pump 10 is lower than a threshold value, the operation control unit 20 opens the backup valve 16 and closes the opening/closing valve 15. When the rotational speed of the vacuum pump 10 is equal to the threshold value, suction side pressure is lower than a pressure upper limit value that indicates an abnormal rise of the suction side pressure.SELECTED DRAWING: Figure 1 |
