Weaverbrook Circular Tank Scrapers : Channels & Weirs
Overflow launders and the associated weirs provide the means for removing supernatant liquid from the thickener or clarifier tank. Material of construction for the Launder can be galvanised carbon steel, stainless steel, G.R.P. or plastic. The 2 principle design of launder channel are :
- ZED Type Launders
- This type is typically bolted directly to the wall of a steel fabricated tank (glass fused to steel panels). The cross section of the launder is a “Z” and when bolted to the side wall of the tank creates the enclosed channel. The ZED type launders can only accommodate single side weir overflow on the inboard side of the launder. A bracketed scum board will also be normally fitted to the inboard side.
- Note : Not recommended for concrete tanks.
- *Download Data Sheet
- Trough Type Launders
- The Trough Type Launder is offset from the wall of the tank and supported on a series of anchor brackets. The gap between the launder channel and tank wall varies on application but typically will be between 250-500mm. On single side weir overflow systems the weir plates are fitted to the outboard side of the launder channel with the inboard side heightened to form an integral scum board. On double weir overflow systems both the inboard and outboard sides of the launder channel are fitted with weir plates and an additional bracketed scum board is fitted to the inboard side. The trough type launder is ideal for concrete tanks to overcome difficulties of fixing to undulating concrete wall finishes.
- *Download Data Sheet (single side weir)
- *Download Data Sheet (double side weir)
Launder Channel Drop Boxes
Each launder channel is equipped with an integral Drop Box where the supernatant liquid is allowed to de-aerate prior to passing to the outlet pipe. The Drop Box will be designed to provide a vertical drop de-accelerated velocity of the discharging liquid.
*Download Data Sheet
Weir Plates are equipped with a regular form of V-notches through which water flows into the launder channel. The standard weir plate conforms to the following conditions :
- The V-notches shall be 50mm deep with a sufficient number to prevent overtopping at maximum flow
- V-notch weirs shall have ±25mm adjustment with final adjustment within ±3mm of datum.
- Fixings shall be a minimum of 100mm down from the top of the weir and a minimum of 400mm apart.
- Weir plates are normally manufactured from RPC (Recycled Polycarbonate), GRP (Glass Reinforced Plastic) or stainless steel. Weir plate sizing will typically be 250mm x 6mm and the V-notch will have a maximum water depth of 50mm.
*Download Data Sheet
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T.P. Aspinall & Sons Limited is a customer focused, innovative, solutions-driven, engineering company which designs, manufactures and installs specialised, be-spoke fabrications, providing both products and services that fully conform to the requirements of our customers and appropriate national and/or international standards.