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Single-Phase Incompressible Flow of Newtonian Fluid
Published in Henry Liu, Pipeline Engineering, 2017
In the analysis of networks of water pipes, to simplify computation (i.e., to reduce iteration and computational time), the Darcy-Weisbach equation is often replaced by the Hazen-Williams equation (Equation 2.41). Results obtained from using the latter are less accurate than from the former. Alternatively, the Darcy-Weisbach equation can be used with the friction factor f treated as a constant for each pipe, determined from the Moody diagram by assuming a velocity in the practical range, say 2 m/s. Using such an approach, the headloss across each pipe can be calculated from hL=CoQ2 where Co is a constant for each pipe equal to Co=8fLgπ2D5
Pipeline Systems
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
The Hazen–Williams equation is valid only when the fluid is water, the flow velocity is less than 3 m/s and the pipe diameter is larger than 2 cm. Users of this equation must be aware that the value of the frictional coefficient varies over a broad range for a given surface and the effect of NR is not considered. However, if the value of C is chosen judiciously, this equation provides good results. The values of the roughness coefficient C for selected pipe materials are given in Table 14.2.
Final Design Considerations
Published in David Thrasher, DESIGN and USE of PRESSURE SEWER SYSTEMS, 2020
A ”C” value of 155 is recommended by Neale and Price15 for smooth plastic pipe. An American Water Works Association committee report16 on plastic pipe states that a Hazen-Williams coefficient of 160 has been observed in plastic pipe, and a conservative value of 150 can be used in determining flow quantities.44
Client-driven performance-evaluation framework for municipal infrastructure
Published in Structure and Infrastructure Engineering, 2022
Khaled Shahata, Samer El-Zahab, Tarek Zayed, Ghasan Alfalah
Assessing the condition of the water mains is a challenging task as compared with other infrastructure assets because these pipes are typically underground, operated under pressure, and mostly inaccessible. The purpose of a condition rating system is to objectively rate or scale the current condition of the buried pipes. Al-Barqawi and Zayed (2006) conducted a comprehensive literature review on the various efforts related to the rating of the water mains’ condition. In this study, the Al-Barqawi and Zayed (2006) condition assessment model using an artificial neural network and analytic hierarchy process (AHP) is used to set up the rehabilitation priority for the water mains. Various factors are incorporated in the developed model, such as physical factors (pipe type, size, age, breakage rate), environmental factors (Cathodic protection, ground water level, soil type, surface type, and road type), and operational factors (Hazen–Williams factor, operational pressure).
Optimal transient network rehabilitation using multi-objective ant colony optimization algorithm
Published in Urban Water Journal, 2018
Hamdy A. El-Ghandour, Amgad S. Elansary
where, Q: volumetric flow rate; H: piezometric head; g: acceleration due to gravity; Ap: cross-sectional area of the pipe; a: celerity of water hammer wave; n: parameter equal to 2.0 for adopting Darcy-Weisbach equation and equal to 1.852 for adopting Hazen-Williams equation; x: distance along the centerline of the pipe; t: time; R in case of Darcy-Weisbach equation and =in case of Hazen-Williams equation; fp: Darcy-Weisbach friction factor; Dp: pipe diameter, and CHW: Hazen-Williams roughness coefficient.
Optimal pipe dimensioning in water distribution networks using Gravitational Search Algorithm
Published in ISH Journal of Hydraulic Engineering, 2021
Hossein Fallah, Sadegh Ghazanfari, C.R. Suribabu, Esmat Rashedi
Two-Reservoir network has been first used by Kadu et al. (2008), which consists of 26 nodes, 34 links and 9 loops and two reservoirs in nodes 1 and 2. Reservoirs water levels are 100 and 95 m, respectively, and Hazen–Williams coefficient is 130 for all links. Network data (pipe lengths, demands and allowable minimum heads in nodes) and its layout are available in Kadu et al. (2008) and Suribabu (2012). For solving this problem, a list of 14 commercially available pipe sizes has been provided by Kadu et al. (2008). Therefore, the problem search space consists of 1434 = 9.3 × 1038 various designs, making this case difficult to solve.