Submersible Mixers – DWM/DNM series

Our submersible mixers keep solids and fibres in suspension which enables the emptying of sumps with a pump, combat settling of solids in corners of larger sumps and prevent floating solids from collecting at the surface and forming the well-known ‘grease layer’. The mixers will keep the floor clean, and the sewage suspended due to the vortex principle. Our customers have found the mixing capacity outstanding, which is why you will find our mixers in many industrial mixing and suspension applications.

Models are available for use in sumps of various sizes and for light or heavier pumping mediums and we can also supply explosion proof versions. The different options are shown in the table below, along with the old Robot identification numbers. The effective area reduces for pumping mediums with a heavier solids content. Please click on the model numbers for data sheets.


Motor Size (kW) Effective Area up to Cast iron Duplex Stainless Steel Hard iron (Nihard4)
0.65 2m DWM22DA
1.5 6m DWM22DC (RM21DC) DWM22DC-U (RM21DC-R) DNM22DC (RM21DC-N)
2.2 8m DWM22DD (RM21DD) DWM22DD-U (RM21DD-R) DNM22DD (RM21DD-N)
3.5 10m DWM22DG (RM21DG) DWM22DG-U (RM21DG-R) DNM22DG (RM21DG-N)
5 12m DWM42DJ (RM40DJ) DWM42DJ-U
6 14m DWM42DL (RM40DL) DWM42DL-U (RM40DL-R) DNM42DL (RM40DL-N)
7.5 16m DWM42DO (RM40DO) DWM42DO-U (RM40DO-R) DNM42DO (RM40DO-N)
13 18m DWM42DZ (RM40DZ) DWM42DZ-U (RM40DZ-R) DNM42DZ (RM40DZ-N)
22 20m DWM62LF (RM60LF) DNM62LF (RM60LF-N)

The mixers are available in cast iron as standard, duplex stainless steel for corrosive applications such as at paper mills, and hard iron (Nihard4) for pumping mediums containing abrasive particles such as iron-oxide slurry.

As the mixers are free-standing, it is easy to place them in positions where they are most effective and move them to other positions as required.


A strong radial flow is created at the impeller level and almost as strong flow in the opposite direction just above floor level. The turbulence whirls up the settled solids and sludge and mixes them with the water throughout the sump. It also prevents the formation of a floating layer / crust at the surface.

For applications which do not allow a free standing mixer, for example due to the characteristics of the sump or chamber floor, the smaller mixers can be fitted with heavy duty stands with fins / wings which prevent rotation when suspended on a chain.