Why should a centrifugal pump never be run empty for more than a moment?

Running a centrifugal pump empty for an extended period can lead to damage to the internal components due to lack of lubrication. Centrifugal pumps rely on the fluid being pumped to provide necessary lubrication and cooling for the moving parts, particularly the impeller and bearings. When the pump operates without fluid, these components can overheat due to friction and wear, ultimately leading to failure.

The lubrication provided by the liquid helps to minimize wear between the rotating parts and their housings. Without this lubrication, parts can grind against each other, causing excessive wear and leading to premature failure. This is particularly critical in applications where the pump is under load, as the lack of fluid increases the chances of damage.

In contrast, other options, such as concerns about energy efficiency or potential freezing, are secondary considerations compared to the primary risk of physical damage due to inadequate lubrication. Therefore, it is essential to ensure that a centrifugal pump is always primed and has a sufficient flow of fluid to avoid these risks.