ACU-PAS Pump Action Screen

Range of Application

The Pump Action Screen (PAS) is a simple and robust CSO
mechanical screen which consists of a half round stainless
steel basket with 6mm perforations, submersible pump,
distribution pipework, and a venturi. It is designed to prevent
the discharge of non-biodegradable solids greater than 6mm
in two directions. The screening debris is scoured from the
underside of the screen basket and punched passed the end
of the screen eliminating potential representation.


  • 6mm screening in two directions
  • Robust proven technology
  • Minimal maintenance
  • No moving parts
  • Modular system for retrofitting through existing manholes
  • Improved screening efficiency due to scour system’s
    reduction of presented screenings
  • No hazardous man entry necessary
  • Introduction of air reduces oxygen demand of the spill
    and pass forward flow

System Operation

The PAS is installed on the flow side of the overflow weir. As the water level rises to the underside of the screen, an ultrasonic head detects the level and sends a signal via the control panel to start the pump. Once the pump has started, it drives the water past a Venturi that entrains air into the flow. The air and water are combined in the mixing section, prior to entering the screen basket. The air/water mixture scours the underside of the screen removing debris and
preventing the screen from blinding. The power of the scouring action transports the screening debris past the end of the screen keeping them in
the continuation flow. Once the flow has subsided, a second signal from the ultrasonic unit switches the pump off.

There are two pump options available for the Pump Action Screen: low level pump or the inline pump.