The impact of a pump inlet pipeline that is smaller than the pump outlet
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The pump’s outlet diameter is 50, while the inlet diameter is 80. Now a pipe with a diameter of 65 is being used at the pump’s inlet. Please help analyze the risk of cavitation
This is not allowed! Cavitation will definitely occur
Is there a problem with the calculation or selection of pipes or equipment? This shouldn’t happen, logically speaking.
To determine whether cavitation occurs, it is necessary to calculate the NPSH value at the inlet and compare it with the pump’s required NPSH value. A reduction in the inlet pipe diameter increases pipe resistance, which in turn raises the pressure drop at the inlet; as a result, the pressure ratio becomes lower compared to when using a DN80 pipe. This increases the likelihood of cavitation. To determine whether cavitation actually occurs, it is still necessary to calculate the NPSH value at the inlet
Changing 65 to 80 definitely won’t cause cavitation; it’s just a waste to use a large pump for a small pipe