AWWA ACE58090

Valves play an important role in water systems by controlling flow and pressure, releasing air, and preventing backflow. One important characteristic of valves in water pumping systems that is often overlooked is the valve's ability to minimize energy consumption. Most engineers are familiar with valve headloss calculations and how they can predict pumping costs but few are aware that the published headloss characteristics of valves presume optimum valve operation (i.e. full-open), which can be affected by valve sizing and flow velocities. Further, studies have shown that the use of air valves can improve the flow efficiency of a water pipeline and thereby reduce energy consumption. While it is important to judge valves on the basis of their headloss characteristics, it will be shown that other characteristics are equally as important. In other words, to minimize energy consumption, an engineer should not simply always select the valve that has the lowest headloss. This paper discusses the flow and operating characteristics of various check valves and pipeline valves and how they impact system performance. Further, the concept of placing and selecting air valves to prevent air binding is also discussed. With an understanding of the effect of various valves on the energy consumption of a system, engineers can calculate the life cycle costs of valve alternatives and make the best decision for the water utility. Includes 9 references, tables, figures.