It doesn’t matter what size, shape or design of the pump its purpose is to move fluids. Head loss that must be overcome makes the task a bit more complicated and the type of pump makes a difference.
Two of the basic pump laws are volumetric flow rate and pump power:
Volumetric Flow Rate:
The capacity of a centrifugal pump is directly proportional to its speed.
Expressed mathematically:
V @ N whereas; V = Volumetric flow rate and N = Speed
If pump speed is doubled, pump capacity will double. If cut 50%, capacity will be halved. Discharge head is directly proportional to the square of pump speed.
Expressed mathematically:
Hp @ N2
If a pump’s speed is doubled, its discharge head will go up by a factor of four.
Pump Power:
Power required by the pump’s driver is directly proportional to the cube of the pump speed.
Expressed mathematically:
P @ N3 whereas: P = Power required and N = Speed
If the pump’s speed is doubled, the power required by its driver will go up by a power of 8!
Why is this important? I will discuss this in a future blog about troubleshooting centrifugal pumps.
