Pumps

Nothing works without pumps!

The human heart is a pump. Pumps form the heart of all fluid circulations. They convey fluids in industrial plants, in private households, in manufacturing facilities and throughout water management systems. The first and oldest pumps known to mankind were used 200 years ago in water supply and irrigation. Pumps continue to convey that vital element known as water right up to the present-day, in clean or contaminated condition, cold or hot, from the largest to the smallest of volumes.

Special pumps of various designs convey crude oil in pipelines over distances of more than 1000 kilometres, convey live fish or fresh tomatoes from one location to another, liquid metal in power station cooling systems or meter the smallest amounts of fluid ( 0.001 litres/h ) in medical apparatus.

The type of pump and capacity required depends on three major aspects:

  • the physical and chemical properties of the medium being conveyed
  • the operating conditions
  • the required delivery volume and, at the same time, the delivery height, both consolidated in the so-called “duty point” of a pump (e.g. 500 l/s at 6 m height)

The essential difference between these two types of pumps is that

  • on rotary pumps the fluid flows constantly so that the pressure energy is fed to the pump such that the fluid is permanently transported onwards by means of rotating blades.
  • in the case of displacement pumps such as piston pumps for example, an exactly determined volume of fluid is enclosed on the suction intake side and discharged through mechanical operation on the pressure side. They do not work continuously but oscillate, pulsate or rotate.

The design of the pump depends on the specific speed. When the specific speed increases, a change is made from oscillating displacement pumps to rotating displacement pumps. The next step is to rotary pumps - first of all to the radials (the pumping medium flows in radial direction through the hydraulic system) via the semi-axial to the so-called axial or propeller pumps.


The above diagram shows the specific speed on the right axis and the achievable pump efficiency on the high axis. One can clearly recognise that the specific speed not only separates displacement pumps and rotary pumps but that within the range of rotary pumps efficiency increases as the delivery volume increases.

Köster builds propeller pumps

KÖSTER has specialised on one particular type within the large family of rotary pumps, namely the so-called propeller or axial pump. As the name suggests, it is a special form of rotary pump in which the pumping medium flows through the impeller (here in the form of a propeller) in the axial direction. Propeller pumps are not self-priming. In other words, the propeller must always be covered by the pumping medium. Delivery heights of up to approx. 10 m can be achieved with this type of pump (special design semi-axial propeller up to approx. 25 m) that has been manufactured now for rd. about 100 years and with very large flow volumes of up to 20 cubic metres per second, corresponding to 72.000 m3/h. This capacity range    of the propeller pump determines its preferred areas of use:

  • agricultural irrigation
  • agricultural drainage
  • settlement drainage (precipitation and mixed water)
  • high water protection
  • conveyance of fluids and re-circulation in the field of environment protection projects and plant construction
  • conveyance of cooling water
  • conveyance of surface water
  • re-circulation / circuits in industrial plants