1. For a pump that operates normally, usually only one pump is used, because a large pump is equivalent to two small pumps working in parallel (referring to the same head and flow rate), and the efficiency of a large pump is higher than that of a small pump. Therefore, from an energy-saving perspective, it is preferable to choose one large pump instead of two small pumps. However, in the following situations, two pumps can be considered for parallel cooperation: the flow rate is high, and one pump cannot reach this flow rate.

2. For large pumps that require a 50% backup rate, two smaller pumps can be changed to work, with two for backup (a total of four)

3. For some large pumps, pumps with a flow rate requirement of 70% can be selected for parallel operation, without the need for backup pumps. During the maintenance of one pump, the other pump still bears 70% of the production transportation.

4. For pumps that require 24-hour continuous operation, three pumps should be standby, one in operation, one for backup, and one for maintenance.