The starting of vacuum pump or pump group belongs to light load starting for prime mover, and there will be no problem when starting in general. However, for some large units, due to the inertia of the unit, it is difficult to start, and there is a large starting current when starting. If you do not pay attention to the starting mode, it will damage the power grid or motor. Therefore, enough attention should be paid to the starting characteristics of different types of pumps.
(1) Zero flow start characteristic of centrifugal pump
The minimum shaft power of centrifugal pump is 30% ~ 90% of rated shaft power under zero flow condition, so the starting characteristic of centrifugal pump is zero flow start (i.e. valve closing start). After the pump reaches the rated speed, the discharge valve can be adjusted to the flow rated point.
(2) Large flow starting characteristics of axial flow pump — full open valve starting
Axial flow pump has the largest shaft power at zero flow rate, 140%~200% of rated shaft power and minimum power of maximum flow. Therefore, in order to minimize the starting current, the starting characteristic of shaft power should be large flow start (full open valve start).
(3) Starting characteristics of mixed flow pump — full open valve starting
Under zero flow condition, the shaft power of the mixed flow pump is between the above two pumps, which is 100% ~ 130% of the rated power. Therefore, the starting characteristics of the mixed flow pump should be between the above two kinds of pumps, and it is better to start with full open valve.
(4) Starting characteristics of scroll pump — full open valve start
It takes a long time for the oil free vortex vacuum pump to reach the limit vacuum when it is started for the first time or is not used for a long time. The starting characteristic of vortex pump should be large flow start (i.e. full open valve start).
Dry scroll vacuum pump