Page 81 - Know and Understand Centrifugal Pumps

Know and Understand Centrifugal Pumps

Figure 6-12
~ ~~~ ~ ~~ ~ ~ ~~ ~~~~~ ~~~ ~ ~~~ ~~
w The can may fracture (see advantages).

w Less efficient than conventional pumps.
w May consume more energy (BHP) than conventional pumps.
w Cannot see the direction of rotation.

Pump impellers

The pump impeller receives the pumped liquid and imparts velocity to
it with help from the electric motor, or driver. The impeller itself looks
like a modified boat or airplane propeller. Actually, boat propellers are
axial flow impellers. Airplane propellers are axial flow impellers also,
except that they are adapted to handle air.
As a general rule, the velocity (speed) of the impeller and the diameter
of the impeller, will determine the head or pressure that the pump can
generate. As a general rule, the velocity and the height of the impeller
blades, will determine the flow (gpm) that the pump can generate
(Figure 6-1 3).

Remember that pumps don't actually generate flow (no pump in the
world can convert three gallons per minute at the suction nozzle into
four gallons per minute out of the discharge nozzle), but this is the
term used in the industry.
Pump impellers have some different design characteristics. Among

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