Wastewater pumps S-WN

The dry installed S-WN horizontal sewage pump with an air-cooled IEC motor. The pump is installed horizontally in a dry pit with flange connection to suction and discharge piping.

From the smallest S-WN1 – suitable for light industrial effluents to the S-WN5 – capable of handling heavy duty wastewater jobs from cities and industries. A flowrate from 68-3500 m3/h and DN50-DN600 with non-clogging impellers.


  • All impellers fit in the same volute
  • Cartridge seal
  • 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

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. They are delivered in cast iron or in stainless steel as an option.

  • One or two channel impeller

    • Higher efficiency and some possibility of clogging
  • B-tween impeller

    • Less efficient than the channel impeller, but lower possibility of clogging
  • Vortex impeller

    • Less efficient, but no clogging

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.

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

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.

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.

Adjustable wear-ring

By this feature the wear-ring can be regularly adjusted to optimize the pump efficiency when the pump starts to be affected by wear.

Elastic coupling

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

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


  • 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