Problems with the straight pipe section and reducer at the inlet of centrifugal pumps
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When piping a centrifugal pump, several issues arise: 1. Is there a requirement for a straight pipe section at the inlet of the centrifugal pump?； 2. When a reducer is needed at the inlet of a centrifugal pump, are there any requirements for the reducer? Is a length difference of 5-7 times the pipe diameter required for the large and small ends?
It depends on the medium being transported. For example, when transporting clean water, the requirements are not strict; it’s sufficient to control the pipe diameter and pay attention to the flow rates at the pump’s inlet and outlet. As for straight sections and elbows, there are no specific requirements – what matters is that the solution is suitable for the task at hand. However, when transporting high-viscosity, highly concentrated media or media with a high solid content that can cause pipe blockages, attention must be paid to the way the pipes are installed in order to prevent blockages; there should be drain outlets as well as connections for flushing water.
When the calculated NPSHa is relatively low, attention should be paid to the piping layout near the pump inlet. If the diameter change between the large and small ends is too drastic, or if bends, valves, etc. are connected directly to the pump inlet, it is easy to cause cavitation in the pump.
When no special medium is being transported, piping is not required. However, the pump inlet pipe must be thicker than the outlet pipe to meet the pump’s installation requirements and ensure proper pressure.