A simple, basic comparison of two of the most used pump types in the world!
The centrifugal pump is the most used pump type in the world. The principle is simple, well-described and thoroughly tested, and the pump is robust, effective and relatively inexpensive to produce.
Positive displacement pumps, on the other hand, operate by forcing a fixed volume of fluid from the inlet pressure section of the pump into the discharge zone of the pump. Positive-displacement pumps frequently are used in hydraulic systems at pressures ranging up to 5000 psi.
Lobe pump is a type of positive displacement pump that offers superb sanitary qualities, high efficiency, reliability, corrosion resistance, and good clean-in-place and sterilise-in-place (CIP/SIP) characteristics.
Before selecting the right pump for the job, we need to understand:
- Total head or pressure against which it must operate
- Desired flow rate
- Suction lift
- Fluid characteristics (temperature, corrosiveness, etc.)
The piping system and pump interact to determine the operating point of pumps: flow rate and pressure.
|Mechanics||Imparts velocity to the liquid resulting in a pressure at the outlet (pressure is created and flow results).||Captures confined amounts of liquid and transfers it from the suction to the discharge port (flow is created and pressure results).|
|Performance||Flow varies with changing pressure.||Flow is constant with changing pressure.|
|Viscosity||Efficiency decreases with increasing viscosity due to frictional losses inside the pump (typically not used on viscosities above 850 cSt).||Efficiency increases with increasing viscosity.|
|Efficiency||Efficiency peaks at best-efficiency-point. At higher or lower pressures, efficiency decreases.||Efficiency increases with increasing pressure.|
|Inlet Conditions||Liquid must be in the pump to create a pressure differential. A dry pump will not prime on its own.||Negative pressure is created at the inlet port. A dry pump will prime on its own.|
If you need assistance with your pump selection, please contact All Pumps today.