Screening panels are carried on a vertical travelling path, between chains suspended from substantial sprockets on a head shaft. The chains/screen panels and guides are contained in a carbon steel or stainless steel screen support structure. A feature of this type of screen is its high capacity per width ratio and ability to deal with large variations in water levels and depths.
Dependant upon the size of screen, the frame will be fabricated from rolled steel sections suitably braced to withstand loads or from pressed and fabricated plate in stainless steel or carbon steel. The head section is fabricated to hold the head shaft in guides and incorporates spray pipes and discharge trough. Covers are manufactured in stainless steel and have inspection windows fitted as standard.
The chains are at pitches of 200, 300 or 450mm depending on the size of the screen. Links are carbon steel plated or stainless steel and are fitted with moulded nylon rollers sized to suit the screen.
Drive to the head shaft, which is supported in heavy duty roller bearings, is normally by a shaft mounted gear reducer often with two speed motor. Motors can be fitted with torque limiting coupling or preferably current sensing overload in control, to prevent damage due to obstruction or overload.
The panel frames are of mild steel or stainless steel construction secured to the chain by stainless steel bolts. The frame carries plastic perforated panels or stainless steel meshes depending upon application and can be removed from outside the screen. The trailing edge of the panel is extended forward to form platforms for lifting larger debris.
Each each panel is fitted with shaped seal plates. This corresponds with fixed side seals to give minimum clearance at sealing between clean and unscreened water.
The screens are fitted with spray header pipe(s) each with a row of jets to wash debris from the panels into the debris trough incorporated into the head covers. Debris troughs can be fitted with extra sparge water supply, dependant upon debris loading.