Which factor will decrease the capacity of a centrifugal pump?

Insufficient suction head is a critical factor that can significantly decrease the capacity of a centrifugal pump. In a centrifugal pump, the suction head is essential for maintaining the appropriate flow of liquid into the pump. When the suction head is insufficient, it can lead to several issues, including cavitation, where vapor bubbles form and disrupt the smooth flow of liquid. This disruption reduces the effective flow and can result in lower pump performance and capacity.

The centrifugal pump relies on a certain level of pressure at the inlet to function properly. Insufficient suction head may lead to a reduction in pressure, preventing the pump from drawing in the required volume of liquid. When this occurs, the pump cannot perform optimally, diminishing its capacity to move water efficiently.

In contrast, excessive suction head can sometimes lead to different operational challenges, but it does not inherently reduce capacity. High water temperature can affect the viscosity of the fluid being pumped, but its impact varies depending on the pump's design and operating conditions. Low water demand may influence the flow rate but does not directly affect the pump’s inherent capacity as a function of suction conditions.