What happens if the horizontal pipe at the inlet of a horizontal centrifugal pump is too long?
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A horizontal centrifugal pump is used for the cooling tower of a project, with a flow rate of 300 cubic meters per hour, a head of 50 meters, and a required net positive suction head of 4 meters. There’s no space to install it; the water pump has to be placed in the pump house on the other side of the road, with the inlet horizontal pipe being over 30 meters long. The pump inlet is below the level of the cooling water tank, and the diameter of the inlet pipe is one size larger than that of the pump’s inlet – DN250. I’ve calculated that the friction loss along the pipeline is not significant, less than 1 meter. But will there be any problems at a distance of over 30 meters?
There will be no problem as long as the pump’s net positive suction head is sufficient. However, the centrifugal pump is strong at the outlet but weak at the inlet; it would be best if this could be changed. After all, with a pipeline over 30 meters long at the inlet, water remaining there for extended periods not only leads to sedimentation and corrosion but also makes it inconvenient to service the valves and pump in that pipeline – even if valves are available, it’s still awkward to have to drain that much water
What is the size in mm for a larger pipe diameter? Study*Study*
As long as the resistance is low and the net positive suction head is sufficient, that’s fine.
Personally, I think the flow rate of the circulating water pump is relatively high; if the inlet pipeline is too long, it will affect the suction flow rate and increase the suction resistance. You can increase the diameter of the inlet pipeline to address this issue.
Under normal circumstances, it won’t. The height of the tower can be appropriately increased to raise the liquid level at the pump inlet. Also, increase the tube size by two levels.
To determine whether cavitation will occur, it is necessary to perform calculations based on the configuration and then conduct on-site tests.