KÖSTER Maschinenfabrik und Gießerei – NPR Niederdruckpumpe Rezirkulation

NPR Low-pressure recirculation pump

Keeps fluids moving

This short horizontal propeller pump was used originally in the treatment of wastewater, where the fluid had to be conveyed from one reservoir in the treatment plant to another neighbouring one.  

The special requirements of wastewater technology led to the construction of this pump for extremely low delivery heights (up to maximum 1.5 m) and with two different installation positions. All that is needed for installation under water with a submersible motor and an automatic quick coupling is a guide rod and coupling claws on the discharge side of the flange.
The important point for the version to be flanged into a dry pipe, i.e. above water, is that in addition to the high level of availability, the rotor assembly remains extractable. The angular gear and propeller are therefore designed in such a way that they can be completely swivelled out of a mounted pipe connection while the pump housing remains in the straight pipe line.  

This type of pump is used typically in the tertiary treatment of wastewater as well as in plant construction and process engineering. Users in the field of plant and process engineering use this pump to boost the pressure of the pumping medium in order to compensate the losses that arise in long pipe lines due to wall friction.
In addition to active sludge and nitrification / denitrification, the NPR also conveys precipitation, surface and river water, pre-treated wastewater as well as industrial process water at temperatures of up to 60°C and other aqueous fluids.


  • The rotor assembly (impeller and angular gear) can be completely extracted from the pump housing
  • The angles of the blades are pre-set, but can be changed manually
  • The propeller is overhung
  • The propeller blades are fibre-repellent
  • The shape of the blades has been hydraulically optimised
  • The pump is driven by a standard or submersible motor with an angular gear
  • The sturdy, watertight encapsulated bevel helical gearbox with its over-dimensioned, oil-lubricated roller bearings is protected from the pumping medium by two independent mechanical seals. There is a filling of biodegradable rapeseed oil between the two seals 

Particularly suitable fields of application

Industrielle Nutzung
Rezirkulation / Umwälzung

Technical data

Hydraulic type: axial

Size DN (mm): 300, 500, 800

Delivery height (m): up to 2

Delivery rating (l/s): up to 1,700

Motor power (kW): up to 22

Rotary assembly extractable: yes

Reverse operation optional: yes

Orientation of the pump shaft: horizontal

Drive motor: electric

Installation of the motor: dry / submerged

Shaft guide bearing: roller bearing



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