If a split casing pump encounters problems during operation, we usually consider that the pump selection may not be optimal or reasonable. Irrational pump selection may be caused by not fully understanding the pump's operating and installation conditions, or by not carefully considering and analyzing the specific situation.

Common errors in split casing pump selection include:

1. The operating range between the maximum and minimum operating flow rates of the pump is not determined. If the selected pump is too large, there will be too much "safety margin" attached to the actual required head and flow, which will cause it to operate under low load. This not only reduces efficiency, but also causes severe vibration and noise, which in turn causes wear and cavitation.

2. The maximum system flow is not specified or corrected. To determine the minimum head required for the entire pump system, the following factors need to be considered:

2-1. Minimum vacuum;

2-2. Maximum inlet pressure during operation;

2-3. Minimum drainage head;

2-4. Maximum suction height;

2-5. Minimum pipeline resistance.

3. In order to reduce costs, the pump size is sometimes selected beyond the required range. This means that the impeller needs to be cut to a certain extent to achieve the specified operating point. There may be backflow at the impeller inlet, which may cause severe noise, vibration and cavitation.

4. The on-site installation conditions of the pump are not fully considered. It is important to arrange the suction pipe reasonably to ensure good inflow conditions.

5. The margin between the NPSHA and NPSH₃(NPSH) selected by the pump is not large enough, which will cause vibration, noise or cavitation.

6. The selected materials are inappropriate (corrosion, wear, cavitation).

7. The mechanical components used are inappropriate.

Only by selecting the right model can the split casing pump be guaranteed to operate stably at the required operating point and the maintenance of the pump can be appropriately reduced.