Pump Recirculation and How You Can Resolve It

The below images depict discharge recirculation on an axial flow pump propeller. Recirculation occurs when the flow is reversed back through the impeller/propeller of the pump. The damage can be seen on each vane at the same location. When there is recirculation in a pump it experiences cavitation and surging that can cause considerable damage.

How do we correct this?

• Increase the output flow of the pump so that it is not operating below its minimum flow requirements.
• Modify the impeller design to more appropriately meet your station design.
• Install a bypass line between the discharge and suction of the pump to allow your pump to meet its minimum flow requirements.
• Upgrade the impeller material to something more resistant to cavitation (Ni-Al-Brz or Stainless Steel for example).