Pump Performance Curves
Identify the appropriate pump performance curves for a system.
Use pump scaling laws to predict the performance of a system.
A centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow. Pumps can generate high volume flow rates when pumping against low-pressure head or low volume flow rates when pumping against high-pressure head. The possible combinations of total pressure and volume flow rate for a specific pump can be plotted to create a pump curve. The curve defines the range of possible operating conditions for the pump. Pump curves plot data on a graph with x and y axes. The x axis (vertical) shows total head while the y axis (horizontal) shows flow capacity, typically gpm.
The operating point is where the system curve and the actual pump curve intersect.
Solved Example: 67-1-01
The system head curve shows:
A. How pump discharge pressure varies with flow
B. How centrifugal pump flow is affected by fluid specific gravity at any given discharge pressure
C. How much head the pump must develop to push fluid through a piping system at any given level of flow
D. How total static head in a centrifugal pump increases at any given level of flow
Correct Answer: C
Solved Example: 67-1-02
A performance curve for a given centrifugal pump shows that:
A. Flow rate increases as the head required to overcome system resistance increases
B. Flow rate decreases as the head required to overcome system resistance increases
C. Flow rate is constant regardless of the head required to overcome system resistance
D. Pump head is constant regardless of flow rate
Correct Answer: B
Solved Example: 67-1-03
The ______________ of a centrifugal pump identifies the point at which the system head curve intersects the pump H-Q curve.
A. Specific speed
B. Brake mean effective pressure
D. Operating point
Correct Answer: D