Progressive Stair Screen PSS

  • Progressive Stair Screen PSS is the worlds strongest “progressive” step screen with the highest capture efficiency on the market
  • Several times stronger frame, bars, drive unit, transmission, bearings than others.
  • Modern easy maintenance construction from robust stainless high quality materials.
  • Totally self cleaning. No spraying or brushes.
  • Totally self aligned bars without rakes.
  • Easy replaceable strong bars and spacers.
  • Flexible mounting angle 35-45 degree.
  • Easy adapted hinged support legs enables quick pivoting out of the channel for service.
  • Enclosed, safe & hygienic with easy to open access doors.

Progressive Stair Screen PSS is a mechanical ”moving bar” fine screen that separates debrie and rubbish from water. Progressive Stair Screen PSS is a further development of the Andersson Stair Screen ASS concept where its progressive motion and progressive stair shape enhances the screenings capture. This is thanks to the PSS lower lifting motion under water which increases the mat support from the back during lifting which prevents screenings from being squeezed through during lifting. The lower lifting motion under water also gives the ability to seal the bottom step which prevents the rush of water through there during lifting. These 2 points enables >80-90% capture on a 1-3mm PSS.

Moving bar step type fine screens has unique capabilities: A 1-6mm Stair Screen can replace a 10-30mm coarse screen
in an existing open channel while maintaining the same low headloss, without any need for pre screening. Stair Screen is totally self cleaning without flushing or brushes. This gives unrivalled capacity, result and total economy.

We recommend PSS for all WWTP headworks with enough channel length to allow 45 deg screen inclination. And where the waterlevels are >800-1000mm. We generally recommend 2mm bar spacing for PSS at WWTP headworks. It is produced with up to 6mm bar spacing but thats generally a waste of separation and capacity capabilities since its rare that a 2mm PSS does not fit existing hydraulics and headworks situations.

At WWTP headworks where the waterlevels are shallow <800-1000mm and the channel length is short, then a 2mm 40-45 deg Progressive Stair Screen PSS may not be suitable. We then advice to use 3mm 50-55 deg Andersson Stair Screen ASS. For industrial applications and WWTPs with freestanding tanks we generally recommend 1-2mm Progressive Stair Screen PSS.


  • Discharge height 700-7000mm
  • Width 200-2500mm
  • Bar spacing 1, 2, 3, 6mm
  • Capacity 10-10000l/s


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