As basic as a butterfly valve is, there are many factors to consider when locating or installing such a valve into a pumping, distribution, or plant piping system. These factors include: the direction of fluid flow through the valve; the presence of upstream and downstream fluid disturbances; the shaft orientation; the rotational direction of disc closure; the proper swing clearance for the valve disc; the valve's proximity to liquid or solid chemical injection systems; fluid hammer; and, the requirements of installation, startup, and maintenance. This article discusses the influence of each of these factors on a butterfly valve's operating performance as well as presenting guidelines for the proper installation of butterfly valves. Although all of the guidelines presented will not always apply in the design and installation of a piping system, if they are understood and considered by the engineer and contractor, the owner should expect maintenance free performance from the AWWA Butterfly valves.