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The Hydro-Jet® Screen is a self-activating, self-cleansing, CSO screening system with no moving parts and no power requirements. A compact device with high hydraulic throughput, the Hydro-Jet® Screen is perfectly suited for small to medium size CSO sites.
A self-cleansing, non-powered screening system for the control of gross solids and floatables in combined sewer systems.
Current regulations demand innovative solutions. The Hydro-Jet® Screen meets that demand by providing an advanced screening system for the removal of material greater than 6 mm in two directions.
The Hydro-Jet® Screen is both innovative and unique. It has no power requirements and no moving parts, yet is self-cleansing and self-activating. An award winning combination that delivers a low maintenance CSO solution and resulting in low whole-life costs.
The Hydro-Jet® Screen can be installed in a purpose built chamber, retrofitted into existing CSO structures, or packaged as a standalone unit.
Dry weather flows pass through the Hydro-Jet® Screen chamber (red arrow) via the dry weather channel and continue downstream to a treatment plant (brown arrow).
During wet weather events, the flow increases as runoff drains into the combined sewer system. The water level in the dry weather flow channel rises as the Hydro-Brake® Flow Control limits the flow passed through the continuation flow outlet.
Water in the dry weather flow channel rises until it spills over the weir wall and flows down through the angled self-cleansing screen.
As the water level under the screen rises to the crest of the siphon the pocket of air trapped between the water surface and the screen creates a backwash mechanism. Debris is lifted off the screen and carried down the screenings channel, which is returned to the continuation flow (brown arrow).
The siphon breaks, discharging the screened effluent (blue arrow) to the receiving water body while drawing down the water level in the overflow spillway.
Typical Design Loading Rate: 200 l/s/m2.
The Hydro-Jet® Screen is a self-cleansing, self-activating, non-powered screening system for the removal of material >6mm 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.
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).
Please use the following link to take you to the standard Hydro-Jet® Screen configurations:
Hydro-Jet® Screen Drawing Page
Flows from 1-450 l/s can generally be accommodated within a rectangular chamber. Due to the size of siphon required, flows greater than 450 l/s will require the L-shaped chamber.
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.
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 200 l/s/m2 . This equates to 150 l/s per screen panel.
The average flow rate through the screenings return Hydro-Brake® Flow Control is in the order of 7.5 l/s for a 150mm outlet diameter Type SXV. A 150 mm 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 Hydro-Brake® Flow Control (>150 mm diameter). 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 continuation flow. Without it, this flow component would increase from 7.5 l/s (150 mm Type SXV) to c.~25 l/s. With less water flowing to the siphon, the time taken for a backwash to occur will increase thus reducing the backwash efficiency.
The weight of a single screen panel (1.215 x 0.641 m) is 20kg.
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.
The Heliscreen® is a compact powered CSO screen with the ability to operate under surcharged conditions. With low headloss and a small footprint, the Heliscreen® is ideal for retrofit installations with hydraulic or physical site constraints.
The Hydro Vortex Drop™ Shaft is a compact, single shaft system used in water conveyance tunnels to dissipate the energy of dropping water from height in order to protect infrastructure from noise, vibration and damage.