Page 96 - Know and Understand Centrifugal Pumps

Understanding Pump Curves

H
Feet

Q
GPM
Figure 7-1
- - ~~ ~~
Once again, imagine starting a pump and raising the fluid in a vertical
tube to the point of maximum elevation. On the curve this would be
maximum head at zero flow. Now, rotate the running pump on its
centerline 90°, until the vertical tube is now in a horizontal position.
The very action of rotating the running pump on its centerline would
trace the pump’s curve. Any elevation in feet would coincide with a
flow in gallons per minute. Consider the graph show in Figure 7-3.
On the graph, if point ‘A’ represents 10 ft of head at 0-gpm, and if
point ‘F’ represents 10 gpm at 0 fi of head, then point ‘C’ on the curve
represents 8 fi of head at 6-gpm. Here we see that the pump is always
on its curve. The pump can operate at any point on this curve from
point ‘A’ to point ‘F’. At any specific head, this pump will pump a
specific flow, or gpm corresponding to the head.

H
Feet
Shut off
’ head

0
0 Q
GPM
Fiaure 7-2