The construction of the centrifugal pump

Pumps are usually named after their structure, function or task. The designation of the centrifugal pump describes the functional principle of this pump. The structure of various centrifugal pumps may differ significantly, since the principle of operation allows different versions.

Centrifugal pumps with hydrodynamic power transmission

The centrifugal pump is the most common type of pump used today in many different applications. Due to the functioning of the centrifugal pump is a pump with hydrodynamic power transmission. In contrast, there is the hydrostatic power transmission, which is found in displacement pumps, so for example in the piston pump.

The different structure of centrifugal pumps after impeller arrangement

The construction of the centrifugal pump is thus in direct relation to the mode of operation. But since different arrangements of individual components (such as the impeller) are possible, there are centrifugal pumps with different names:

  • Radial pumps (also referred to as a propeller pump)
  • Axial pumps
  • mixed-flow pumps

Structure according to fluid flow properties

In addition, however, centrifugal pumps are also distinguished according to how the fluid to be delivered is conducted:

  • Diagonal pumps
  • Side channel pumps
  • peripheral pumps

Basic structure of centrifugal or centrifugal pumps

It describes how the impeller shape is arranged concretely (from axial to radial). Basically, the construction of a centrifugal pump is always the same:

  • Suction side (suction of the pumped fluid)
  • Pressure side (outlet of the pumped fluid)
  • pump housing
  • Impeller or impeller
  • drive shaft
  • Drive (mechanical manual, electric, etc.)

Special features of the drive shaft

Depending on the concrete construction, it is a continuous or split drive shaft. The continuous drive shaft must be sealed towards the engine. There are wet rotors among the centrifugal pumps where the impeller is kept away from the stator by sitting in a pot. This is sealed with a mechanical seal, which is maintenance-free.

Centrifugal pumps with radial shaft seal on the drive shaft

However, the most common sealing method is a radial shaft end seal between pump housing and drive shaft mounted. This is a consumable part, which is why centrifugal pumps with a radial shaft seal are not maintenance-free. The radial seal has almost completely replaced the oldest method of drive shaft sealing - the so-called stuffing seal or stuffing box. A cord made of asbestos (formerly) or PTFE (modern) is wound around the shaft and pressed in.

Centrifugal pumps drive shafts with magnetic coupling

Opposite is still the drive side closed pump or impeller housing. However, these housings can not be made of magnetic metal, but are mainly made of plastic. The power transmission then takes place via a magnetic coupling, which also explains why the housing must not be magnetic. A typical application for this design is the drain pump in dishwashers or washing machines.

Important performance parameters

Depending on the structure, the pump performance also results. There are three important values:

  • the flow rate of the fluid
  • the speed of the impeller
  • the funding amount

The pump capacity is influenced by the design

The values ​​are also in direct relation to each other, of course, can also be influenced individually. The impeller in the pump sets the fluid in motion and pushes it against the housing wall, which is why the centrifugal pump is also called centrifugal pump. Thus, in addition to the speed and the diameter of the impeller is of crucial importance. The flow rate is defined among other things by the line cross sections.

Tips & Tricks

As can be deduced, the construction of the centrifugal pump is relatively simple. In addition, the pump can of course be equipped with control valves and other control technology such as sensors and the like. Due to their simple design, centrifugal pumps achieve a considerable service life. Therefore, they can be found in the house or in the building services often as a circulation pump for heating or as a submersible pump or sewage pump in the basement.

Video Board: Centrifugal Pump | Construction | Principle | Working