Centrifugal pumps are among the most popular garden pumps. How this special garden pump works is not clear to everyone. How it works is explained in this article.

In a nutshell

  • Centrifugal pumps use centrifugal forces
  • generate negative pressure
  • are not self-priming
  • Side channel pumps are self-priming

Centrifugal pumps: How they work explained

The function of the centrifugal pump is simpler than you might think. It uses centrifugal forces that create pressure inside the housing and thus pump water. Due to the way centrifugal pumps work, it is necessary that they are already in contact with water or another fluid. Since they cannot suck up the medium themselves, direct contact is important. For this reason, many centrifugal pumps are filled before use and offered as submersible pumps that are permanently placed in the water. As soon as the medium is available and there is no oxygen in the housing, the centrifugal pump can work. It must be deflated before use. The following guide explains how it works:

  • Pump is switched on
  • Impellers start rotating
  • rotate around drive shaft
  • Water in the housing is moved
  • Rotation creates pressure
  • negative pressure in the center
  • overpressure on the outside
  • Water is pressed against the housing wall by centrifugal forces
  • then transported away through openings (e.g. outlet valves).
The rotating impellers create a vacuum in the center while the pressure increases on the outside, moving the liquid.

If the pump is not switched off, it continues to work continuously and pumps water until there is not enough water left. Centrifugal pumps do not work without a medium. Depending on the design of the pump, the medium is moved in different directions, which affects the pumping options. The main issue here is the position of the impeller relative to the axis of rotation:

  • axial
  • radial
  • semi-axial
  • parallel

You therefore determine the type of centrifugal pump and the possible applications. The most commonly used garden pumps are:

  • Axial pump: for low-viscosity media
  • Radial pump: for viscous media

Notice: Due to the way they work, centrifugal pumps are comparable to a centrifugal pump.

Self-priming pump: how it works

There are self-priming garden pumps that are based on the concept of a centrifugal pump. They are offered under the designation side channel pump and use an extended mode of operation. You don't have to worry about oxygen or other gases in the device. They easily suck in and move the medium, even when significant amounts of gases are present. This is possible through the combination of a flow pump (centrifugal pump) and positive displacement pump. Compared to centrifugal pumps, they cannot transport solids, which must be taken into account when using them.

Side channel pumps are often used to pump media with a higher proportion of gas (up to 50 percent by volume).

The function in detail:

  • have an additional impeller in front of the impeller
  • Paddle wheel is spiral
  • Pump is switched on
  • Water and gases are moved as with centrifugal pumps
  • Water is pushed into side channels by pressure
  • Side channels transport water to the impeller and further
  • Gases are discharged separately
  • a liquid ring behind the impeller is used for this

Notice: Another form of self-priming garden pump is the jet pump, which is not based on centrifugal pumps. It uses no moving parts to transport water and is therefore low-maintenance.

frequently asked Questions

Can centrifugal pumps transport solids?

Not exclusively. They can only carry solids within the fluid. This means that small stones or pieces of earth, for example, are transported and do not damage the centrifugal pump. Since the solids in the water only come into contact with the impeller and casing, they can be safely used for solids transport. The ball passage indicates the maximum diameter for solids in millimeters.

Do centrifugal pumps need maintenance?

Yes, especially when used without a solids filter or specifically for pumping liquids containing solids. The solids wear the impellers heavily, which makes it necessary to check them periodically and replace them if necessary.

Why do centrifugal pumps have to be vented?

The ventilation of centrifugal pumps is essential, since even small amounts of air significantly impair the effect. Already at eight to ten percent, the performance of the garden pump is noticeably poorer. In some models, they even fail completely because the air content can no longer build up enough pressure.

Category:

Garden design