What risk is associated with insufficient suction head in a centrifugal pump?

Insufficient suction head in a centrifugal pump can lead to a decreased pump capacity because the pump requires an adequate amount of liquid at its inlet to maintain proper flow. When the suction head is too low, the pump may not bring in enough fluid, resulting in cavitation, which can disrupt the flow and reduce the overall capacity of the pump to move water efficiently. This inadequate inflow can also result in decreased performance and inability to maintain the desired pressure and flow rates, leading to issues such as overheating and potential damage to the pump components over time, but the primary and immediate consequence remains the compromised capacity to deliver water as intended.

Other options like overheating of the motor and unstable pressure readings can be consequences of a reduced capacity but are not the primary risk associated with insufficient suction head itself. Excessive water flow is not applicable here as insufficient suction head generally results in less than optimal flow rather than an increase.