DIY Coanda Intake Screen

If you would like to make use of our affordable and efficient Coanda screen in an intake structure of your own design then this is the product for you.

The PowerSpout Coanda intake screen removes rubbish, stones, leaves and aquatic life forms from the flow prior to entering the supply pipe (penstock). This is often a requirement of environmental protection agencies. A poor intake is normally the cause of most hydro turbine system problems. Poor intakes may allow small stones to enter the penstock that can cause serious damage to the Pelton rotor or cause the jets to suddenly block resulting in severe water hammer that can rupture pipe and fittings.

Our Coanda intake screen is not limited to small hydro schemes, it can also be used for domestic, farm, village and small town water supplies.

Our Coanda intake screens are designed to provide low maintenance screening solutions for water intakes without the need for any moving parts. The self-cleaning ability and high abstraction flow capacity is due to the shape of the screen and the arrangement of the wedge wires that make up the screen.

The Coanda screen uses the Coanda effect, which is the phenomena in which a jet flow attaches itself to a solid surface and remains attached, even when the surface curves away from the initial jet direction. The screen is built from wedge-shaped wires that have suitably angled faces to which the flow attaches.

Water is directed over the screen in a fast moving sheet, and the bars deflect it into a tank below whilst debris continues straight on and is washed off by the surplus flow.

Water and some fine silt particles (<1.5mm) pass through the screen, whilst larger silt and debris is excluded and deposited downstream. During times of low river flow the screen capacity may be greater than the available water. Under these conditions debris can build up on the lower parts of the screen. This will be washed off the next time the river flow rises above the screen capacity.

Screen Specifications:

• Material: 304 stainless steel
• Screen gap: 1.5mm
• Wedge wire tilt angle: 5 degrees
• Wedge wire width: 2mm
• Wedge wire depth: 3mm
• Supporting bar: 3mm wide x 5mm deep at 20mm spacing
• Screen angle relative to flow rate: 0 to 40 degrees (we recommend 25-35 degrees)
• Rated load: A person of 100kg can stand on the screen without damage.
• Please note that screens have a slight warp from welding stress, this warp pulls out to flat once the screen is secured to your intake box

Half Screen:

• Width x length: 380mm x 188mm 
• Effective width x length installed: 360mm x 168mm
• Approved nominal flow: 8l/s

Full Screen:

• Width x length: 380mm x 380mm 
• Effective width x length installed: 360mm x 360mm
• Approved nominal flow: 17l/s

You can also add an optional acceleration plate in the dropdown menu. It is important to make some form of acceleration plate to ensure good contact of the water flow with the coanda screen. 

We also offer complete full and half screen intakes.

You can find the product manual here, and also our general intake guide here.

Refer to PowerSpout Document Index Links for a complete index of documents.