Frequently Asked Questions

Q. What is a Hydro-Static Screen?

A. The Hydro-Static Screen is a self-activating, non-powered screening system for the removal of material >6 mm in two directions. The screen is designed to intercept and retain aesthetically offensive material and gross solids at all states of flow up to the peak storm flow, with the material remaining in the foul sewer during and after the storm event. The screen can be configured as an Up Flow Screen or a weir-mounted through flow screen.

Q. What advantages does the Hydro-Static Screen offer?

A. Patented flow modifying baffles are used on the Up Flow Hydro-Static Screen to encourage a re-circulation pattern above and below the screen panels. This flow pattern helps reduce any blinding effect when the screen is in operation. The Up Flow Hydro-Static Screen is also configured so that the top of the corrugated screen sits below the weir level. Once a storm has subsided this will allow a volume of water to backwash the screen panels helping to remove any debris that may be caught on the underside of the screen.

The Through Flow Hydro-Static Screen is offset from the vertical to encourage screening to drop away from the corrugated mesh one the storm has subsided.

Q. Is the Hydro-Static Screen manufactured in standard sizes?

A. We try to encourage the use of standard screen panels (4 ft X 2 ft) however we can design Hydro-Static Screens specific to each application. We are usually able to offer a viable solution by cutting/extending our screen panels to suit without any increase in cost. This can be particularly useful for retrofit solutions.

Q. What are the loading rates/head loss figures for the Hydro-Static Screen?

A. The Hydro-Static Screen has undergone independent testing at the national CSO testing facility at Wigan Wastewater Treatment Works. Following on from this testing the recommended design loading range for the Hydro-Static Screen is 73 to 143 US gal/min/ft2 (nominal value = 110 US gal/min/ft2 ).

Head Loss figures for a 50% blinded screen at various loading rates are as follows:

Q. What is the weight of a screen panel?

A. The weight of a standard panel (4 ft X 2 ft) is 44 lbs. This equates to 56.5 lbs of plan area and this value should be applied to non-standard panels.