difference between positive displacement pump and centrifugal pump|positive displacement pump disadvantages : commercial In centrifugal pumps, the flow varies with change in pressure whereas in positive displacement pumps flow remains constant with changing pressure. For both pumps, flow can be regulated by changing the speed. Fig. 1 below shows how a centrifugal pump and … See more Noxon develops, sells, manufactures and service decanter centrifuges used for separating particles from liquid. From our facilities in Fjärås just south of Kungsbacka we deliver decanters to municipal and industrial applications .
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When it comes to pumping fluids in various industries, two common types of pumps are often used - positive displacement pumps and centrifugal pumps. Both serve the purpose of moving liquids from one place to another, but they operate in different ways and have distinct characteristics. Understanding the difference between positive displacement pumps and centrifugal pumps is crucial for selecting the right pump for a specific application. In this article, we will delve into the variances between these two types of pumps, their advantages and disadvantages, working principles, and more.
With an increase in the fluid viscosity, the efficiency of the centrifugal pump decreases due to frictional losses. That’s why centrifugal pumps are not suitable for highly viscous fluids. Whereas, with an increase in viscosity, the efficiency of the positive displacement pump increases. Also, positive
Difference Between Centrifugal Pump and Positive Displacement
One of the key differences between centrifugal pumps and positive displacement pumps lies in how they handle changes in pressure and flow. In centrifugal pumps, the flow rate varies with the change in pressure. As the pressure increases, the flow rate decreases, and vice versa. This is due to the pump's operating principle, which relies on the conversion of rotational energy into kinetic energy to increase the fluid's velocity and create pressure.
On the other hand, positive displacement pumps maintain a constant flow rate regardless of changes in pressure. These pumps operate by trapping a specific volume of fluid and then displacing it through the system. This results in a steady flow rate that is not affected by fluctuations in pressure. Positive displacement pumps are suitable for applications where a consistent flow rate is required, such as in dosing systems or metering applications.
Positive Displacement Pump Disadvantages
While positive displacement pumps offer a reliable and consistent flow rate, they also have some disadvantages compared to centrifugal pumps. One of the main drawbacks of positive displacement pumps is their limited ability to handle high flow rates. Due to their operating principle of trapping and displacing a fixed volume of fluid, these pumps may struggle to accommodate large volumes of liquid compared to centrifugal pumps, which can handle higher flow rates more efficiently.
Another disadvantage of positive displacement pumps is their sensitivity to viscosity changes. These pumps may experience difficulties when pumping fluids with varying viscosities, as the consistency of the flow rate can be affected. In contrast, centrifugal pumps are more versatile in handling fluids with different viscosities, making them suitable for a wider range of applications.
Positive Displacement Pump vs Diaphragm
One common type of positive displacement pump is the diaphragm pump, which uses a flexible diaphragm to displace the fluid. Diaphragm pumps are known for their ability to handle abrasive or viscous fluids, as the diaphragm acts as a barrier between the fluid and the pump components, reducing wear and tear. These pumps are often used in applications where the pumped fluid may contain solids or harsh chemicals.
While diaphragm pumps are a type of positive displacement pump, they have specific advantages and disadvantages compared to other positive displacement pumps. Diaphragm pumps are self-priming, meaning they can create a suction to draw the fluid into the pump without external assistance. This makes them suitable for applications where the pump may need to operate in a low-pressure environment.
Characteristics of Positive Displacement Pump
Positive displacement pumps have several key characteristics that set them apart from centrifugal pumps. One of the main features of positive displacement pumps is their ability to provide a constant flow rate, making them ideal for applications that require precise dosing or metering of fluids. These pumps are also known for their high efficiency, as they can maintain a consistent flow rate even at high pressures.
Another characteristic of positive displacement pumps is their ability to generate high pressures. Due to their operating principle of trapping and displacing fluid, these pumps can produce significant pressure levels, making them suitable for applications that require pumping fluids over long distances or against high head pressures. Positive displacement pumps are also known for their ability to handle viscous fluids and maintain a steady flow rate, even with varying viscosities.
Positive Displacement Pump Working Principle
The working principle of a positive displacement pump involves the trapping and displacement of a specific volume of fluid with each cycle of operation. These pumps use a chamber or cavity to capture the fluid, then decrease the volume of the chamber to displace the fluid through the system. This action creates a continuous flow of liquid, with the pump delivering a consistent flow rate regardless of changes in pressure.
There are several types of positive displacement pumps, including gear pumps, piston pumps, and rotary pumps, each operating on the same basic principle of trapping and displacing fluid. These pumps are commonly used in applications where a precise and constant flow rate is required, such as in chemical processing, food and beverage production, and pharmaceutical manufacturing.
Centrifugal Pump vs Submersible
In addition to positive displacement pumps, centrifugal pumps are another common type of pump used in various industries. Centrifugal pumps operate on a different principle than positive displacement pumps, relying on the conversion of rotational energy into kinetic energy to move the fluid through the system. These pumps are known for their high flow rates and ability to handle large volumes of liquid efficiently.
One specific type of centrifugal pump is the submersible pump, which is designed to be submerged in the fluid being pumped. Submersible pumps are commonly used in applications where the pump needs to be located underwater, such as in wells, sumps, or sewage systems. These pumps are sealed to prevent water ingress and are capable of handling high flow rates and pressures.
Centrifugal Pump vs Rotary
Another type of centrifugal pump is the rotary pump, which operates on a similar principle to centrifugal pumps but with a different design. Rotary pumps use rotating impellers or gears to create centrifugal force and move the fluid through the system. These pumps are known for their high efficiency and ability to handle viscous fluids, making them suitable for applications where a consistent flow rate is required.
Compared to positive displacement pumps, rotary pumps offer higher flow rates and can handle a wider range of viscosities. However, rotary pumps may not be as precise in dosing or metering applications as positive displacement pumps. The choice between a centrifugal pump and a rotary pump depends on the specific requirements of the application and the characteristics of the fluid being pumped.
Conclusion
Centrifugal Pumps are high-speed pumps. It causes shearing of liquids. Hence, not suitable for sensitive mediums. On the other hand, positive displacement pumps operate at lower velocities which causes very little shear. See more
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difference between positive displacement pump and centrifugal pump|positive displacement pump disadvantages