North Carolina Surface Water Practice Exam

The discharge rate of a piston-type pump is constant at a constant speed due to the mechanics of how these pumps operate. When a piston pump runs at a steady speed, it draws in a fixed volume of fluid with each stroke of the piston. This predictable stroke volume results in a steady flow rate, as long as conditions such as fluid viscosity and pump wear remain constant.

In practical terms, if the pump speed changes, the volume of fluid moved per unit of time will also vary, leading to fluctuations in discharge rate. Additionally, while variations in head and static pressure can affect the pump performance, the inherent design of a piston pump allows it to maintain a consistent discharge rate at a constant speed, assuming other variables remain unchanged. Therefore, recognizing that the rate of discharge in piston-type pumps relies heavily on maintaining consistent operational speeds can help in understanding pump selection and application in various settings.