Some questions catch you by surprise. I certainly was caught off guard when someone at a plant asked: “Are centrifugal pump inlet velocity limits calculated based on the inlet piping or the inlet nozzle?” Quite honestly, I couldn’t ever remember paying any special attention to a pump inlet velocity when sizing lines or selecting pumps.
In many cases, inlet velocity to a pumping system is important. However, that’s because the velocity affects inlet head losses, nozzle sizes or strainer requirements — not because it’s a specific requirement for pump selection.
The concept of a velocity limit on centrifugal pump suction lines has some merit, though. High velocities can lead to pronounced flow patterns at the impeller inlet. This may reduce pump performance and reliability.
Protecting electrical controls and equipment within food and beverage plants presents unique challenges due to the sanitation requirements of the hygienic environment.
