Hydropower / Coanda Screens

The Hydropower / Coanda Screens, also known as the overflow sieve (or weir) screen and diversion screen, was developed to accommodate a need for a remotely located intake screen in mountain streams supplying water to a mini hydro scheme. The system was required to be virtually maintenance free from screen fouling by water borne debris and capable of delivering sufficient particle free water to drive the turbine efficiently without damage.

This concept has found its way into water supply schemes for villages and towns, the limit to intake capacity being a function of the size of flow of the water source. The patented concept and design minimizes debris impingement by maintaining enough water flow over the screen surface to sweep any solids off the end of the screen. As long as the upstream pool surface is 4.3 in. / 110 mm above the sieve or weir crest, adequate flow will occur. If the pool surface exceeds 4.3 in. / 110 mm, the excess water will pass over the screen and on downstream. If the head over the weir crest falls below 4.3 in. / 110 mm, debris will begin to accumulate on the screen surface. This accumulation will not adversely affect through-screen capacity but will hinder waste by-pass. The screen structure is of quite durable construction and will pass small tree limbs and stones without being damaged.

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