Some of the most attractive hydro sites are plagued by silt at certain times of the year. Silt erosion of the hydraulic turbines at these sites is typically controlled by upstream settling chambers and turbine protective coatings; however, further work is needed to better predict and control silt erosion. The problem of hydro-abrasive erosion of hydraulic machinery is not limited to hydroelectric plants. Similar problems to those encountered in hydroelectric work are also prevalent in the mining industry, dredging work, and waste disposal. The blades of gas turbines are subjected to erosion from high-velocity solid particles and those of steam turbines from liquid droplets. Although experience gained in other industries can and is applied to similar problems in hydraulic turbines, hydro requirements are somewhat unique in requiring high machine efficiencies over relatively long periods between maintenance and in the unpredictability of the concentration, shape, and mineral composition of the particle load to be combated.
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