The FSM Alpha Beta Escalator screen is an innovative inlet screen and storm screen which allows higher hydraulic flows to pass through a fixed channel when compared to a conventional escalator screen.  The FSM Alpha Beta Escalator screen can remove double the amount of screenings when compared to a conventional 6 mm bar raked screen.

The FSM Alpha Beta Escalator screen can be channel mounted or in a stainless steel tank as part of a Design for Manufacture Assembly (DfMA) package.


  • Inlet works screening with up to 82% retention of screened material.
  • Increasing screening capacity at WwTWs without the need for extensive civils works.
  • Screening of storm flows at WwTWs to ensure no unscreened sewage is released to watercourses.
  • Screening of flows from Combined Sewer Overflow (CSO) points.

Supported by M&N, our Uk Wastewater Services team.



Prevent screenings clogging up treatment plant

The FSM Alpha Beta screen with 6 mm perforated screen panels removes up to 82% of screenings, preventing the build-up of screenings and resultant clogging of downstream process plant.

Increase throughput

The 30° angle of the screen below the water level provides nearly double the screen surface available for screening and enabling an increase in flow throughput without extensive civils.

Protect efficiency of downstream equipment

Removing more solids than conventional screens, the FSM Frankenberger Alpha Beta screen can improve the efficiency of ferric dosing plants, and also protect Membrane Bioreactor (MBR) processes, helping to reduce the amount of phosphorus that needs to be removed before discharge to a watercourse. We can deliver fine screening, often down to 1-3 mm for MBR protection.

How it works

How it works

  1. The inlet flow is directed over the submerged 30° angled part of the screen. Particulates are caught on the screen and lifted up the screen on the filter belt to the above water 70° section of the screen.
  2. Every 10th screen panel (site specific) is fitted with rag lifters which ensure that rags are removed and prevent clogging.
  3. The filter belt with collected screenings, moves up to the top section of the screen.  Here, the main cleaning system, a hard-wearing brush,  continuously cleans the screenings from filter belt.  A secondary means of cleaning the screen are automatic water jets, which help remove the screenings in proportion to the screenings load.
  4. The screened flow that has passed through the FSM Alpha Beta Escalator screen continues along the inlet channel to the next wastewater treatment process.
Technical information

Technical information


Filter width:  300 to 3,000 mm

Shaft centre distance:  up to 11,000 mm (larger sizes available on request)

Filter panel hole size:  2-12 mm (other sizes available on request)

Water level difference:  up to 2,000 mm possible (larger differentials available on request)

Mounting angle:  30° / 75° (other angles available on request)

Component Materials

Frame:  Stainless steel SS304 or SS316L

Filter panel:  Stainless steel SS304 or SS316L

Chains:  Wear resistant stainless steel bush conveyor chain

Chain wheels:  Wear resistant steel or stainless steel

Chain supports:  Ultra high molecular polyethylene (UHMP)

Base sealing:  Brush & neoprene double sealing

Side sealing:  Ultra high molecular polyethylene (UHMP)

Filter belt:  Cleaning rotary brush segments constructed of PP or nylon drives

Geared motors:  SEW or equivalent.



Case Studies

Case Studies