As a pump user, you will be confronted with the decision as to whether your application requires a dynamic or positive displacement pump.
There are two general types:
1. Rotodynamic (which the main subclassification is centrifugal)
2. Positive displacement
Rotodynamic
Rotodynamic pumps are rotary machines in which energy is continuously imparted to the pumped liquid by a rotating impeller, propeller or rotor.
Positive displacement
Positive displacement pumps are rotary or reciprocating machines in which energy is periodically added by application of force to movable boundaries of enclosed fluid containing volumes, resulting in a direct increase in pressure.
Which to use?
In general, the basic conclusion/rule is that:
• Centrifugal pumps are for pumping clean, low viscosity liquids
• Positive displacement pumps are best for slurries and high viscosity liquids
As with all general rules there are important exceptions – in fact there are times when you can use a centrifugal pump on high viscosity and when you can employ a positive displacement pump for clean, cold, low viscosity liquids. If in doubt, consult your pump supplier.
Article courtesy of Kelair Pumps Australia “When Pump Knowledge Matters” Phone 1300 789 466, or visit www.kelairpumps.com.au.
