Gufler Metall KG from the Passeier Valley in South Tyrol has been satisfying customers on the inner-Alpine hydropower market with its hydraulic steel construction products for over three decades. Gufler Metall provides modern solutions, especially debris rakes and screen cleaning machinery, impressing operators with their functionality, durability and robustness. The portfolio ranges from self-cleaning Coanda rakes to various types of telescopic and excavator-arm screen cleaners. The list of hydropower industry references for these solutions alone is extremely long, highlighting the expertise and quality offered by this South Tyrolean company in screens and screen cleaners.

The machine efficiency of a hydropower plant is often measured to the second decimal point, but is determined overall by more than just the performance of its ­machines. The trash rack situation is at least as important and determines whether the available motive water is drawn at optimum volumes and speeds, or whether there are ­efficiency losses due to blockages caused by debris or leaves. Hence, a completely unobstructed inlet screen is absolutely invaluable. Technical solutions for debris-free screens have existed for decades. Over time, companies have continually optimised them to serve the needs of power plant operators; ultimately developing them to become completely self-cleaning plant components. Gufler Metall KG is a medium-sized South Tyrolean company, based in Moos in the ­Passeier Valley. It has been active in this ­market segment for over three decades and has built up an excellent reputation for its ­hydraulic steel construction solutions. It is acknowledged for its expertise in steel pipe welding, and valued throughout the Alpine region for its hydraulic steel engineering ­solutions, high-quality rake screens and screen cleaning machinery.

Coanda system experience
Today, Gufler Metall is one of the few ­suppliers in our part of the world to offer a self-cleaning protective Coanda rake in its product portfolio. The Coanda rake has ­established itself as an economically and ecologically viable option for water catchments on mountain streams with high wash loads and bed loads, particularly in Alpine regions. Thanks to the system’s inherent wall adhesion effect, and to the shearing effect on the profile bars, the Coanda rake is effective at preventing sediment and smaller aquatic organisms from flowing into the catchment system. ­There is also an inherent ecological benefit as flotsam, debris and leaves deposited on the Coanda screen are removed by water flowing over it and moving it on downstream. This makes screen cleaning machinery obsolete, and allows a reduction in the cubic capacity of the connected desander – in turn having a positive effect on hydropower plant profitability.
The Gufler Metall Coanda screen is made entirely of stainless steel – and in various designs. The fine screen retains particles of up to 0.5 mm in size. The Passeier industry specialists have been installing their Coanda systems for over 20 years, and experience has shown that these systems still run smoothly, even in midwinter at air temperatures down to -25°C.

Counter-rake system proves its worth
Of course, there is still demand for classic ­Tyrolean weirs and various forms of inlet screens. Gufler Metall meets this demand with rake systems built using raw metal, hot-dip galvanised metal and stainless steel. Protective steel cladding and built-in residual water ­basins are also supplied on request. Similarly, there is still a need for modern screen cleaning machines, to which Gufler Metall responds with single and multiple telescopic versions, and with excavator arm screen cleaners. The experienced hydraulic steel construction ­specialists from the Passeier Valley also supply the appropriate hydraulic drive systems – via hydraulic cylinders and power packs and, on request, produce electromechanical drives. The hydraulically operated counter-rake ­deployed to clean the inside of Tyrolean weirs was ingeniously custom-designed and pur­pose-­built by the South Tyroleans, using an­other rake that moves up from the base of the weir body and into the openings between the profile bars during the cleaning process. A ­hydraulic cylinder pushes the movable rake arm upwards at the pivot point, ensuring all the small material and debris that has collected on the rake or between the bars is transported to the surface and washed away. Although this is still not a common solution, it is extremely practical for water catchments exposed to heavy debris flow.

Integrity and reliability count
Today there’s a long list of references con­firming the dependability of the technical ­solutions provided by Gufler Metall. It in­cludes the most important power plant projects in South Tyrol’s recent past, and ­numerous projects in neighbouring countries. Renowned operators such as Vorarlberg’s ­illwerke vkw, ÖBB and TIWAG in Tyrol, to name just a few, rely on the expertise and ­quality of these industry specialists from the Passeier Valley. The virtues of integrity and reliability, adherence to deadlines and a ­guarantee of supreme quality, still remain ­decisive factors in Alpine hydropower.