Characteristics And Limitations of Centrifugal Pumps
What are the main features of centrifugal pumps?
The Centrifugal Pump Supplier tells us that there are two main series of pumps: centrifugal pumps and positive displacement pumps. Compared with the latter, centrifugal pumps are usually designated for higher flow rates and low viscosity liquids as low as 0.1 cP. In some chemical plants, 90% of the pumps used are centrifugal pumps. However, in many applications, positive displacement pumps are preferred.
What are the limitations of centrifugal pumps?
The effective operation of a centrifugal pump depends on the constant, high-speed rotation of its impeller. For high-viscosity feeds, the efficiency of centrifugal pumps is getting lower and lower: the resistance is greater, and higher pressures are required to maintain a specific flow. Therefore, in general, centrifugal pumps are suitable for low-pressure, high-volume, pumping applications for liquids with a viscosity between 0.1 and 200 cP.
Slurry such as mud or high-viscosity oil can cause excessive wear and overheating, which can lead to damage and premature failure. Positive Displacement Pumps usually run at fairly low speeds and are less prone to these problems.
Any pumping medium sensitive to shear (separation of emulsions, slurries or biological liquids) will also be damaged by the high speed of the centrifugal pump impeller. In this case, it is preferable that the rotational speed of the displacement pump is lower.
Another limitation is that, unlike positive displacement pumps, centrifugal pumps cannot provide suction when dry: they must first be primed with pumped fluid. Therefore, Centrifugal Pumps are not suitable for any application with intermittent supply. In addition, if the feed pressure is variable, the centrifugal pump will produce a variable flow; the positive displacement pump is insensitive to pressure changes and will provide a constant output. Therefore, in applications requiring precise metering, positive displacement pumps are preferred.