The need to use pipes in the industrial area usually stems from the fact that the point of generation or storage of fluids is generally far from its point of use. The facilities for this purpose are mainly composed of pipes and fittings. Among these accessories, valves are devices that control the flow of fluids, and perform irreplaceable paper in hydraulic installations, accounting for 20 to 30% of pipe costs, and about 8% of the total cost of a plant . With the aim of evaluating and improving the efficiency of the use of valves in industrial pipes, this book aims to numerically analyze the flow in a butterfly valve in a water pipe, to obtain variations of pressure and other physical characteristics, and to compare the Data obtained from the numerical simulation with the actual load loss data on a butterfly valve in a water pipe.