Radial flow pumps

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No pump technology is used more frequently around the world than centrifugal pumps, and among centrifugal pumps, radial pumps are number one. They are the solid workhorses among flow machines. But what makes these hydraulic units with rotating impellers so popular? Their compact design, high handling pressures, and individual designs are the keys to the popularity of these flexible continuous runners.

Delivery characteristics of the available Radial Pumps
 

Delivery output: up to 600 m³/h

Delivery height: up to approx. 330 m  (1083 ft)

Solids content: up to max. 15 % and up to a max. grain size of 80 mm

Gas content: up to max. 30 %

Operating pressure: up to max. 40 bar

Self-priming: partially

How does a radial pump work

Their name suggests how radial pumps work. With these pumps, the fluid handled is conveyed radially: It enters via the suction pipe, is collected by the impeller, and then escapes vertically to the pump shaft from the pump's impeller and through a spiral casing. This materials handling method that uses centrifugal force enables higher pressures than can be achieved with axial pumps, where the fluids are conveyed axially, that is, parallel to the pump shaft.

A radial pump’s impeller sits permanently on the pump shaft and has vanes that exert force on the fluid handled, thus increasing the angular momentum. Since this increases the pressure and speed, energy is transferred to the fluid. With a diffuser element, this energy is transformed into additional static pressure energy. In state-of-the-art radial pumps, spiral casings or vaned diffusers perform this task. The diffuser element and impeller together determine the pump’s hydraulics.

Multi-stage variant for higher handling pressures

 

The handling pressures achieved are proportional to the diameter of the impeller used in a radial pump. Multi-stage models for higher pressures are also available. These pumps have several impellers arranged one after another. Here, the radial flow is fed axially by diffusers to the next stage, which further increases efficiency and handling pressure.

Whether single- or multi-stage – radial pumps feature a compact design and are available with impellers in different shapes and models: Depending on the application, the impeller can be radial, semi-axial or axial and open, semi-open or closed.

Multi-stage radial pump

Simple drive, many designs

In contrast to many positive displacement pumps, direct drive without gears is possible for centrifugal pumps that are radial pumps. This special feature offers operational advantages such as high efficiency and lower-complexity construction. The simpler design also makes servicing and any required repairs easier.

Radial pumps can be set up dry, immersed or some even submerged completely. They are available with various sealing systems, both in hermetically sealed models with magnetic coupling and in special designs with a can as a canned motor pump. Other special models of this type of pump are free-flow pumps and plastic pumps, where the main components of the inner workings are made of different plastics or coated with these.

Benefits of radial pumps as compared to other pump technologies

The property that particularly distinguishes radial pumps is their especially great flexibility. With high pump capacities and heads, they offer an enormously broad field of applications. Radial pumps can also withstand high operating pressures. Accordingly, they are used in nearly all areas of industry, including:

  • Food and beverage production, pharmacy
  • Heating and cooling
  • Chemical industry
  • Tank storage and systems
  • Surface engineering and cleaning
  • Shipbuilding
  • Water and wastewater

Radial pumps convey pulsation-free and offer the same efficiency across broad pump outputs. This is possible since the impellers and diffuser elements are adapted to the respective impeller diameters. The axial thrust-free, open impeller construction enables low bearing loads and a longer service life.
 

Adapted variants for special applications

To enable use in various applications, manufacturers have also developed special forms of the radial pump. These include self-priming pumps, which can ventilate their pump suction line without tools, and so-called multi-phase pumps: These are constructed for integrated handling of fluid-gas mixtures and generating dispersions. They can also handle fluid media that consist of up to 30% gas.

For which fluids are radial pumps suited?

Radial pumps are suitable for handling incompressible fluids, which can also contain gases or small percentages of solids. Generally, centrifugal pumps are used to handle water. More precise applications can include drinking water, cooling water, wastewater and sewage, handling in the course of water treatment, and filling and emptying tanks.

But radial pumps can handle many other fluids. Generally, all water-like and low-viscosity media are possible. These include different kinds of fuels, refrigerants & coolants, fluid gases, fluids that contain gases, fluid hydrocarbons, acids and alkalis. They can even be used for oils if the viscosity is not too high and many other fluids in addition to those named above.

 

Thanks to their compact, high-performance, uncomplicated design and easy servicing, radial pumps are continuous runners for a wide variety of fluids handled and applications, and they prove themselves millions of times over every day around the world. This pump type could be just the right choice for your application.

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