In the practical production, when the single centrifugal pump can’t meet the transportation tasks, we can use the parallel and series of centrifugal pump.
The parallel
If the same model centrifugal pump is parallel and each inlet line is all the same, the flow and head of the two pumps must be respectively same, it has the same pipeline performance and the single pump performance.
The parallel operation can be used in centrifugal pump. If need the bigger flow and low head, also the flow is bigger than the flow which is produced by single pump, sometimes use two parallel centrifugal pumps meet the requirements. The two pump independent suction, then is injected the same pipeline, in order to reach the same total moving head. If the two pumps is same, export total head is equal to the head which is produced by the two pumps, the flow is the two times of the single pump. But the two centrifugal pumps can’t produce the same export head, but because the wear effect, one of the pump head will be less than the other pump. The power is produced by the greater ability pump is bigger than the other pump. So the parallel operation is not widely used.
The series
Most of the time, the single centrifugal pump can’t meet the requirements of the needing head. Using the two pumps series, the export of the before pump is as the feeding month of the after pump, it can obtains the needing head.
If the same model pump is series, the flow and head of each pumps are all the same, so in the same flow, the head of the two series pump is the second times of the single pump. when the pump is used with series, it can’ t extend the safety working limit of flange plate, otherwise, the series pump don’t need to install too close.