Differences Between Positive Displacement and Centrifugal Pumps

Positive displacement pumps and centrifugal pumps are two common types of pumps used in various applications.

Positive displacement pumps work by trapping a fixed amount of fluid in a chamber and then forcing it through an outlet. This type of pump can produce a constant flow rate regardless of changes in pressure. Positive displacement pumps are typically used for pumping viscous fluids, such as oil or syrup, and for applications that require high-pressure output.

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On the other hand, centrifugal pumps work by converting rotational energy from an impeller into kinetic energy in the fluid. This creates a pressure differential that moves the fluid from the inlet to the outlet. The flow rate of a centrifugal pump depends on the pressure and can change with changes in pressure. Centrifugal pumps are commonly used for pumping fluids with low viscosity, such as water, and for applications that require a high flow rate.

In summary, the main differences between positive displacement and centrifugal pumps are:

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1. Flow rate: Positive displacement pumps produce a constant flow rate, while centrifugal pumps have a flow rate that depends on the pressure.
2. Pressure: Positive displacement pumps are better suited for high-pressure applications, while centrifugal pumps are better suited for low to medium pressure applications.
3. Fluid type: Positive displacement pumps are better suited for pumping viscous fluids, while centrifugal pumps are better suited for pumping fluids with low viscosity.
4. Efficiency: Positive displacement pumps are generally more efficient at low flow rates and high pressures, while centrifugal pumps are more efficient at high flow rates and low pressures.
5. Cost: Positive displacement pumps are generally more expensive than centrifugal pumps due to their more complex design and materials.