Frequently Asked Questions

Q. What is the Heliscreen?

A. The Heliscreen is an automatic self-cleaning powered screening system for the screening of material >6 mm in two directions. Each Heliscreen uses a 6mm stainless steel perforated screen foil which allows excess storm flow to discharge to an alternative water course (or storage) while ensuring that the screenings are retained within the chamber / sewer system. The Heliscreen is continually brushed clean to ensure the foil does not blind and that the flow is discharged freely.

Q. What advantages does the Heliscreen offer?

A. The Heliscreen is normally cantilevered from the weir wall within CSO chambers. As the Heliscreen retains solids in the foul flow (to treatment) the Heliscreen can continue to operate even when the continuation pipe and/or spill flow pipes are completely surcharged. Also, as the screen overhangs the main through flow channel any required maintenance can be undertaken from the dry side of the weir.

Q. What is the maximum loading rate for the Heliscreen?

A. Following independent testing of the Heliscreen at the national CSO testing facility at Wigan and Knostrop Wastewater Treatment Works, the maximum recommended loading rate for the Heliscreen is 515 gal/min/ft2.

Q. What are the power requirements of the Heliscreen?

A. The Heliscreen requires 380-415v 3-phase supply. A single-phase motor can be provided on request. All diameters up to 11 ft. in length use a 0.75 kw motor. All diameters >11 ft. in length use the 1.1 kw motor.

The Heliscreen can also be powered via a Hydraulic drive if it is desirable to keep the electrical motor out of the CSO.

Q. What Heliscreen sizes are available?

A. The diameters of Heliscreen available are 300, 500, 700 and 1000 mm. The effective lengths of screens range from 1.5 m to 7 m in 0.5 m increments up to 4.0 m then 1 m increments up to 7 m. When considering a particular spill flow, more than one Heliscreen may be available for selection. The engineer can decide which to opt for by considering the weir length required.

Q. What is the weight of a screen panel?

A. The weight of the screen panels varies depending on the diameter of unit. The maximum weight of any one screen however will not exceed 55 lbs.

Q. What is the head loss imposed by the screen?

A. This is dependant on the spill flow and diameter of unit. Please contact Hydro International for further information.