What is the effect on pump discharge when the head decreases?

When the head decreases in a pumping system, the discharge typically increases. This phenomenon can be understood through the principles of pump performance and the relationship between head and flow rate.

In a centrifugal pump, the head is a measure of the energy imparted to the water as it is moved through the system. When the system head decreases, it means that the resistance against which the pump works is reduced. As a result, the pump can push more water through the discharge line because it does not have to exert as much energy to overcome the system's resistance.

This behavior is reflected in the pump's characteristic curve, which illustrates that at lower heads, the flow rate (discharge) tends to increase. A lower system head allows the pump to operate more efficiently and increases the amount of water being discharged.

Other answer choices suggest different outcomes that do not align with the principles of how centrifugal pumps operate under varying head conditions. Discharge remaining constant or decreasing does not accurately depict the expected behavior of a pump as head changes in these systems. Thus, the correct understanding is that a decrease in head leads to an increase in discharge.