Frequently Asked Questions

Q. What is a Hydro-Jet Screen?

A. The Hydro-Jet Screen is a self-cleansing, self-activating, non-powered screening system for the removal of material ¼" in two directions. The screen is designed to intercept and retain aesthetically offensive material and gross solids at all states of flow to the peak storm flow, with the material being returned to the foul sewer during and after the storm event.

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

A. The Hydro-Jet Screen is designed to operate as a fully automatic, self-cleansing high performance screening system. The main advantages of the Hydro-Jet Screen are that it has no moving parts and no power requirements. This significantly reduces the maintenance commitment and whole-life running costs. Rather than any form of mechanical cleansing, the screen is kept clean by a dynamic backwashing system produced by the hydraulic head present within the sewer system (see flash animation for further details).

Q. What Hydro-Jet Screen sizes are available?

A. Please use the following link to take you to the standard Hydro-Jet Screen configurations: Hydro-Jet Screen Drawing PageFlows from 1-10 mgd can generally be accommodated within a rectangular chamber. Due to the size of siphon required, flows greater than 10 mgd will require the L-shaped chamber.

Q. Can the Hydro-Jet Screen be retrofitted within existing chambers?

A. The Hydro-Jet Screen has successfully been retrofitted into many existing CSO's. Due to the specific restraints of such projects the layout of the key Hydro-Jet Screen components (siphon, screen, weir etc) may differ from those suggested in our standard arrangement. If a retrofit is being considered then we suggest contacting Hydro direct with details of the existing structure for confirmation of suitability.

Q. What is the maximum loading rate for the Hydro-Jet Screen?

A. Following independent testing of the Hydro-Jet Screen at the national CSO testing facility at Wigan Wastewater Treatment Works, the maximum recommended loading rate for the Hydro-Jet Screen is 294 US gal/min/ft2 . This equates to 3.4 mgd per screen panel.

Q. What is the return flow from the screenings return Reg-U-Flo® Vortex Valve? Is it always required?

A. The average flow rate through the screenings return Reg-U-Flo Vortex Valve is in the order of 119 gpm for a 6 inch outlet diameter Type SXV. A 6 inch outlet diameter is the minimum recommended size unit for use on foul and combined sewer systems. In some instances there may be scope to increase the size of the screenings return Reg-U-Flo Vortex Valve. This will however depend on the continuation flow rate into the downstream sewer. The screenings return flow control is an integral part of the Hydro-Jet Screen system. It is essential to restrict the amount of flow that is returned to the collection system. Without it, this flow component would be substantially more. With less water flowing to the siphon, the time taken for a backwash to occur will increase thus reducing the backwash efficiency.

Q. What is the weight of a screen panel?

A. The weight of a single screen panel (4 ft X 2 ft) is 44 lbs.

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

A. The Hydro-Jet Screen is unlike weir mounted screening systems/devices that impose an additional head loss on the system that needs to be taken into account. The top water level in the Hydro-Jet Screen under normal operating conditions is determined by the weir level and weir length for a given flow rate since the siphon has a capacity in excess of the incoming design flow.