Wastewater pumps S-WN

Wastewater pump applications

The dry installed DanPumps serie S-WN are used for horizontal and vertical mounting. They are driven by an air-cooled IEC motor and connected with the piping with flanges on both suction and discharge sides.

With the range of pumps from the small S-WN1 to the big S-WN5, we cover the need from light industrial effluents to heavy duty wastewater jobs from both cities and industries. The flowrate varies from 68m³/h to 4000 m³/h, and we have connections from DN50 to DN600.

The S-WN pumps can be used in many different applications by adjusting motor size and impeller type, the solution can easily be customized to comply with your requirements.



  • All impellers fit in the same volute
  • Cartridge seal
  • Ambient temperature and media up to max.: 75°C
  • High-efficiency motors from well-known suppliers
  • Easy maintenance
  • Dry-installed, therefor no risk of contamination
  • No need for entry into pump stations
  • Easy removal of the motor without disconnecting the pump
  • Offer frequency converter
S-WN wastewater pump
S-WN open pump







The design of the S-WN pump is a combination between high efficiency, intelligent design and practical features.

The efficiency of the pump is very important to be able to reduce running costs of the pump, and in the same time reduce the CO2 release to the environment, which is achieved by the design of the impeller and use of high-efficient motors – it gives you a user-friendly pump with a long-life cycle which will reduce maintenance costs.


When choosing the impeller

The choice of impellers depends on the nature of particles in the fluid. Designed to fit in the same volute and customized according to customers demand.

By optimizing the impeller, we make sure to hit the wished duty point and thereby saving energy consumption.

Can be delivered in cast iron, stainless steel and duplex as an option.

Choose the most optimal impeller:

  • One or two channel impeller

    - Higher efficiency (70-80%) and some possibility of clogging


  • B-tween impeller

    - Less efficient (60-75%) than the channel impeller, but lower possibility of clogging


  • Vortex impeller

    -Less efficient (30-40%), but it is clogging free due to free passage, therefore it is reliable

Cutter impeller

A cutter impeller for the S-WP and S-WN wastewater pump specially designed to handle solids. The impeller has sharp edged scissor like vanes with blades designed to grind any solids before they enter the pump.

  • Non-clogging impeller
  • Cutting action for your toughest challenges
  • Multi-vanes design for the highest possible efficiency

The cutter impeller is perfect for pumping heavy wastewater/sewage and is designed for providing excellent cutting mechanism to shred diapers, sanitary pads, rags, plastic bags, sludge and fish silage in residential, commercial and aqua cultural applications.

The impeller is made of AISI 316, and the blades are made of hardened tool steel to overcome heavy-duty challenges. 

Cartridge seal

A user-friendly cartridge seal that makes it possible to change the seal without using any special tools or personal with specific skills, which eliminates any risk of improper installation.

The cartridge seal has built in an impeller for circulation of motor cooling fluid. The cartridge seal is pressure tested before shipment and ready for assembling.

Double seals are generally used with unstable, lightly toxic, abrasive, corrosive and viscous fluids. 

How to replace the cartridge seal:

  • Tap oil
  • Loosen latch bolts
  • Tap cooling water from the cooling jacket
  • Remove impeller
  • 4 bolts for release
  • 2 pull threads

See animation

We have done the work for you – all-in-one to provide simple sealing solution and ease of installation. The service time of the seal is reduced compared to a normal double mechanical seal.

See assembly of cartridge seal


The casing is the major stationary component of the pump and mainly provides two functions:

  • Converting velocity head from the impeller into pressure head and guidance of the flow to the discharge connection
  • Creating a pressure boundary for the pumped liquid

A volute is a spiral-like form such that as the liquid is discharged from the impeller into the volute casing, the volute areas increase at a rate proportional to the discharge of liquid from the impeller and a constant velocity exists around the periphery of the impeller.

High-efficiency Motors

DanPumps only uses electrical motors from first class suppliers.

The electric motors are manufactured according to international standards regarding IEC 60034-30 and are fulfilling the requirements of the EC Directive 2009/125 (eco-design for energy-related products).

All Motors are standard IP55, prepared for drain holes. Higher protection class on request. All motors are delivered with blind caps in the terminal box.

And beside the standard motor we also supply the pumps with Explosion Proof motors for all classifications and different zones.

ATEX approved is optional.

Fast lock latch bolts

To separate the pump very easily from the motor when doing service.

The pump will be separated thus the rest of the pump is lifted up without affecting the pipework.

This feature is very popular with the service staff, as it reduces to
maintenance downtime considerably.

The locks are made in stainless steel.

Oil tap drain

It is important to tap the oil before removing the cartridge seal.

The pumps are equipped with oil tap drain making service and oil change very easy.

Flexible coupling

When transferring the power from the electrical motor, we use a flexible coupling made of cast iron and rubber with taper-lock bush that connects.
The design of the flexible coupling is suitable for absorbing vibrations and minimizes disparities.

The design of our flexible coupling causes gentle operation of the pump and thus prolonging the lifetime of a pump.

Pump cables

The S-WN pump as a standard comes without cables, however DanPumps do offer cables as an option.

The H07RN-F cable:

  • Tough & flexible cable
  • Excellent moisture, abrasion & weather resistance
  • Safe, reliable and power saving
  • Available in 10m


The RS PRO SY screened cable for the frequency converter


Vertical wastewater pump


  • Requires a smaller footprint than a horizontal pump
  • Adjustable legs which makes installation easier
  • Top pull-out construction, easy access to the pump parts
  • Easy disassembly when making service
Horizontal wastewater pump


  • Easy dry installation
  • The pump is on a baseplate, which makes service easy
  • Pump parts are easily accessible
  • Suitable for almost all indoor applications due to its low headroom requirements


Pump curves - 50 Hz

Wastewater pump curves - 50 Hz

60 Hz

Wastewater pump curves - 60 Hz


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