Determination of Economical Pipe Diameters in Distribution Systems

trol the design of a water distribution system are so complex and often so incapable of rationalization that, up to the present, the problem of determining the most economical combination of pipe sizes, pumping head and elevated storage in a water system has been badly neglected. A general solution is impractical in systems of rugged terrain because the problem there is exceedingly complex. In a simple system, however, where the terrain is level, it is possible 'to produce general equations showing the interdependence of the variables. It is the purpose of this paper to develop the equations for a simple system with the expectation that the knowledge of the interdependence of the variables in ' these cases might produce a better understanding of the problem and, perhaps, lead to better designs. The outstanding advances in distribution system analyses of the last few years by Cross (1), Doland (2), Aldrich (3) and Camp and Hazen (4), improving upon the earlier work by Freeman (5), have contributed much toward making solutions of certain phases of the problem possible. These methods of analysis, however, are only the means to study a system once it is designed; or possibly to examine laboriously a few of the infinite combinations of pipe, sizes, input heads and elevated storage only one combination of which provides the lowest annual cost. Howson (6) has emphasized the importance of the distribution system and the additional attention it deserves. Probably the most valuable contribution toward the design of distribution systems is that of Camp (7), in which a definite technique is developed for the determination of economical pipe sizes.