The Dual Flow and Dual Flow Conversion band screens have been installed at intakes at numerous applications throughout the United States where they have significantly reduced fouling of down stream pumps, condenser tubes, heat exchangers, membrane reactors, disinfection processes and/or critical water treatment monitoring equipment. Their superior performance is due to their design, which avoids the disadvantages of conventional Thru Flow traveling band screens by minimizing maintenance costs, as well as station down time. The Dual Flow band screen can be, in most cases, retrofit into the existing well of a Thru Flow screen without any civil modifications. Design features remain constant, with the addition of flow diverters which are fixed to the main frame structure and completely seal off the influent from the effluent. Less restrictive and more efficient than the Thru Flow band screen, the Dual Flow and Dual Flow Conversion band screens combine maximum capacity with superior debris removal.

The major problem with Thru Flow traveling band screens is debris carry-over; a condition inherent in their design. This persists no matter how well tuned and maintained the screen may be. Regardless of the flow rate, velocity, debris loading and spray wash configuration, there will always be areas on the screening panels which cannot, (because of their inaccessibility) be effectively cleaned. In the Thru Flow screen, the debris-laden mesh is carried over the head sprockets and back down into the clean effluent side of the screen. The debris dislodged by the water then flows downstream to foul critical heat exchange equipment and/or tertiary treatment processes. The Thru Flow is also twice (2X) the effective width of a Dual Flow creating excessive weight, additional maintenance and requires more costly spares for reliability.

The Dual Flow design avoids the use of submerged shaft and lower sprocket assemblies of the Thru Flow screen. The screen width is approximately half of an equivalent Thru Flow screen reducing the band weight and consequent maintenance costs. The problem of debris carryover has been eliminated in the design of the Dual Flow band screen, which operates at 90 degrees from the Thru Flow, permanently sealing off the influent debris from the effluent and allows only filtered water to pass downstream. Regardless of the efficiency of the spray wash system, debris carry over is impossible. Debris not cleared from the screen mesh by one cleaning cycle simply returns to the influent water to be removed by the next. Seals between adjacent panels and between the moving band and side frame completely isolate the debris loaded water from the clean water side of the band. Because debris is collected on both the ascending and descending sides of the Dual Flow band screen, width requirements for a given screening area are reduced. This results in a more economical design with a lower total screen weight.

Other Features

Corner Wear Rims (10) and Wear Bars (11) support the ascending and descending mesh panels while significantly extending the life of the carrier chain, rollers, and supporting frame. Other features include a Head Sprocket (12), driven by a shaft mounted drive (13) and anti-friction bearings to reduce maintenance. An enclosed head section with viewing windows provides easy observation and accessibility. Rigid frame (14) construction for durability and long life. Sealed front plate (15) to direct flow and eliminate bypassing. Roll around foot section (16) to eliminate foot sprockets and reduce maintenance. Positive sealing so that nothing larger than the mesh opening can bypass the screen.