Centrifugal pumps are pumps in which fluid movement is provided by rotating mechanical parts (often called "impellers").

The main components of the centrifugal pump are:

• Moving parts that transmit energy, called impellers

• The pump housing, the volute that directs the water flow, is drawn first and then discharged

• The impeller is fixed to it and connected to the shaft of the motor

• Motor, can be electric or internal combustion

There are obviously different types of centrifugal pumps, such as the magnetically driven type, in which motion is transferred to the impeller by magnetic force rather than through the rotating shaft.

Classification and installation

According to the position of the shaft and motor, there are:

• Horizontal centrifugal pump, usually located outside the tank

• Vertical centrifugal pump, partially submerged in liquid

Horizontal pumps can also be divided into:

• Pumps above the head, where the distance between the pump and the suction fluid surface is positive and there is a risk of cavitation.

• The pump head is lower than the pump head, the distance between the pump and the suction fluid surface is negative, and cavitation is rare.

Centrifugal pump: Operation

How does the centrifugal pump work? To work, centrifugal pumps use the centrifugal action of the impeller to pump fluid, converting mechanical energy (from the motor, which in most cases is electric) into kinetic energy, which is then converted into pressure.

The movement of the impeller creates a vacuum in the suction pipe, and the fluid, pushed by atmospheric pressure, flows into the pipe and into the pump. After the impeller inhales the fluid, the centrifugal force generated by its speed is used to send the fluid to both sides of the pump housing.

The main types of centrifugal pump impeller are:

• Open when the fluid is dirty

• Closure, when efficiency is preferred over versatility

The impeller of the centrifugal pump is fitted with a series of curved blades that form channels that increase cross section from the center outwards. The fluid leaves the impeller at speed Vt, so it still has kinetic energy and enters the volute.

The centrifugal pump housing, or volute, is also constructed with an increased cross-section, so that the remaining kinetic energy is converted into pressure, thereby increasing the head.

Centrifugal pump performance

The characteristics of the centrifugal pump are described by a curve that shows the relationship between the head provided by the pump and the flow rate provided. These vary depending on the size of the impeller.

In practice, a curve of NPSH (net positive suction head) and absorbed power is provided, taking into account flow and sometimes also performance.

How to choose a centrifugal pump that meets your requirements?

Knowing how to choose the right pump type and size is crucial when building a plant, creating production cycles, fluid transfer operations, and more.

Size of centrifugal pump

Why is it important to choose the right pump size? The correct centrifugal pump size is important for two reasons:

• First, ensure the correct supply of fluids required during the normal life cycle.

• Estimate costs arising from procurement and use, called project costs and operating costs, respectively

• In practice, attempts are made to avoid oversize in order to minimize operating costs.

What are the parameters that determine the most appropriate pump?

• Quantity and head, in other words, how much volume (m^3/h) or mass (kg/h) flow needs to be achieved, which head needs to be highlighted. When calculating the pump head, different factors must be kept in mind: loss due to the normal flow of fluid along the pipe (distribution loss); Losses (concentrated losses) due to equipment elements found along the line, such as valves, pipe elbows, check valves and fittings; Finally, consider the uneven level to be overcome when pumping the fluid from point A to point B (surveying head).

• Fluid characteristics. Fluids also play a key role in selection. Its temperature, density, viscosity and the properties of the fluid itself, and whether there are particles in it. The temperature and properties of the fluid affect the choice of materials that make up the pump. Density and viscosity are important parameters to consider when selecting engine power and impeller type and size (open or closed and outside diameter), respectively, without forgetting their contribution to calculating pipe losses. The presence of particles determines the type of pump, with mechanical seals (lip, bellows...) Or pump with magnetic drive.

• Positioning. Select pumps with vertical or horizontal axes depending on their location within the plant. Centrifugal pumps are efficient tools. However, their operational requirements do not make them universal. In many cases, positive displacement pumps will act voluntarily.

The above describes how to select centrifugal pumps,KNOLLKono centrifugal pumpProblems with the installation and operation process. In addition, Shenzhen Oudejie Technology specializes in selling new imported KNOLL centrifugal pumps, and promises to sell products are new imported products, while providing our customers with quotation, selection, product information and other services.