text: In a hydraulic engineering application, it is typical for the volumetric flow  within a pipe (that is, its productivity) and the head loss per unit length  (the concomitant power consumption) to be the critical important factors. The practical consequence is that, for a fixed volumetric flow rate , head loss  decreases with the inverse fifth power of the pipe diameter, .  Doubling the diameter of a pipe of a given schedule (say, ANSI schedule 40) roughly doubles the amount of material required per unit length and thus its installed cost. Meanwhile, the head loss is decreased by a factor of 32 (about a 97% reduction). Thus the energy consumed in moving a given volumetric flow of the fluid is cut down dramatically for a modest increase in capital cost.