Understanding Pump Curves
The NPSHR Characteristic
The graph below shows us the Head Flow Characteristic (black curve) with the NPSHR Flow Characteristic (red curve). The NPSHR Flow Characteristic has its own scale calibrated in Feet of Head located on the lower right hand side of the graph. The NPSHR value, together with other pump characteristics, is used to design the pump intake so that the pump will have sufficient NPSHA to avoid suction cavitation.
In the graph above, the red curve line shows the NPSHR for this pump at various flow rates. All centrifugal pumps have a NPSHR value directly proportional to flow rate, (NPSHR always increases with increased flow rate).
In the graph above, the NPSHR value for this pump when operating at 160 gpm is 10 Feet of Head. When the pump is delivering 320 gpm the NPSHR value is 16 Feet of Head.
Related Topics on this Website:
Follow the links below to pages focusing on other types of information provided in the Pump Characteristic and more, including graphs and explanations.
