AWWA JAW69828

Water demand varies rapidly with both time and local pressure, which strongly influences surge response in the distribution system. The constant or pressure-insensitive demand model frequently used for surge analysis ignores the pressure-sensitive characteristic inherent in actual networks. The assumption of constant demand can exaggerate the magnitude of a surge wave in the system, which may lead to overdesign of surge-protection devices and unnecessary costs. Results from a comparative study indicated that replacing the pressure-insensitive demand model with a pressure-sensitive orifice model facilitates a more accurate estimate of water hammer phenomena as well as proper assessment and cost-effective selection of strategies for surge protection and control. Enhancement of distribution system operation and management is a principal benefit of the proposed demand model. Many water utilities are facing upgrades and modifications needed to improve system performance and protect public health. Good management decisions based on sound modeling procedures will be required if these improvements are to be effective and economical. Includes 31 references, tables, figures.