Pump flow rate decreases
Thread Content
For pumping, the inlets of the two self-priming pumps share a single DN100 pipe, and their outlets also share one outlet pipe, with the diameter changing from DN100 to 150. When only one pump is in operation, the flow rate is 80 M3; the designed capacity for a single pump is 120 M3. If both are turned on at the same time, the traffic does not increase; instead, it decreases.
The pump inlet pipe is too small; with two pumps in use, the suction volume is insufficient, which can easily lead to cavitation. It seems that the piping configuration isn’t appropriate – generally, the pump inlet pipe should be larger than the pump outlet pipe
The import volume is only 100, and they’re still used together; the export volume is higher than the import volume. It’s already good that both units can operate at the same time without any vacuum conditions arising.
It’s likely that the diameter of the inlet pipe is too small; moreover, the two pumps share one inlet pipe. It could also be that it’s a self-priming pump with insufficient suction capacity, resulting in cavitation inside the pump casing. With prolonged operation, it’s a good thing if the pump impeller isn’t damaged.
The inlet pipe should be changed to DN200; if this section of the pipe is relatively short, DN150 can also be used.