A centrifugal pump is limited to use where the lift of the water is not in excess of?

A centrifugal pump operates effectively within specific hydraulic limits, and one crucial parameter is the lift, which is the vertical distance the pump must move the water. In general, centrifugal pumps are not efficient for lifts greater than 15 feet due to the limitations of atmospheric pressure and the behavior of fluids in motion.

When attempting to lift water beyond this threshold, the performance of the pump diminishes significantly due to issues such as cavitation, which occurs when the pressure in the pump drops below the vapor pressure of water, causing vapor bubbles to form. These bubbles can collapse violently, leading to potential damage to the pump and reduction in efficiency.

Thus, 15 feet is considered the practical upper limit for the lift of water using a centrifugal pump under normal atmospheric conditions, making it the correct answer in this context.