Hazen-Williams Formula

For liquids flowing in pipes the pressure drop is commonly taken proportional to a power of the flow rate, usually around 2. One of the simplest correlations used in water distribution network calculation is the Hazen-Williams formula,3... 

Some simplification is permissible for water distribution systems in metallic pipes. Then the Hazen-Williams formula is adequate, namely... 

Compute the friction-head loss using the Hazen-WiUiams formula. The Hazen-Williams formula is hf = (u/1.318C/ ° 63) 85, where h j = friction-head loss per foot of pipe, in feet of water v = water velocity, in ft/s C = a constant depending on the condition and kind of pipe and Rh = hydraulic radius of pipe, in ft. 

For coated cast-iron pipe in fair condition, n = 0.013, and hj= 0.0411 ft of water. For 2500 ft of pipe, the total friction-head loss = 2500(0.0411) = 102.8 ft (31.4 m) of water, as compared with 112.9 ft of water computed with the Hazen-Williams formula. Thus the Manning formula gives results higher than the Hazen-Williams in one case and lower in another. However, the differences in each case are not excessive (73.8 — 65.9)/65.9 = 0.12, or 12 percent higher, and (112.9 — 102.8)/102.8 = 0.0983, or 9.83 percent lower. Both these differences are within the normal range of accuracy expected in pipe friction-head calculations. 

Hazen-Williams formula from small to large pipes. Despite the fact that commercial publications from pipe suppliers sometimes use ... 

Hazen-Williams Equation The Hazen-Williams Equation is used primarily in the design and analysis of pressure pipe for water distribution systems. This equation was developed experimentally with water and, under most conditions, should not be used for other fluids. The Hazen-Williams formula for water at 60 F, however, can be applied to liquids that have the same kinematic viscosity as water. This... 

For a simpler solution to fluid flow in plastic pipe, consider this version of the Hazen-Williams formula ... 

There are also many empirical formulas used for calculating the friction head loss in piping systems. These must be used carefully because many are based on the properties of specific fluids and are not applicable over a broad range of fluids, temperatures, and pressures. For example, the Hazen and Williams formula widely used for water flow ... 

Flow in a pipe is predicted by Hazen Williams [7] with the following formula ... 

The first set of constraints represents the mass conservation law at each node of the water network. The second set describes the energy (head) losses for each pipe in the network to relate the pressure drop (head loss), due to friction, to the pipe flow rate and the diameter, roughness, material of construction, and length of the pipe. In this work, the commonly used Hazen-Williams empirical formula (Alperovits Shamir, 1977 Cunha Sousa, 1999 Coulter Morgan, 1985) is used. The third set of constraints includes bounds on variables such as minimum head or flowrate requirements. This set also includes constraints to ensure that only one diameter can be selected for each pipe (stream), a more realistic representation rather than having a split-pipe design. 

Determine the friction-head loss in 2500 ft of clean 10-in new tar-dipped cast-iron pipe when 2000 gal/min (0.126 m /s) of cold water is flowing. What is the friction-head loss 20 years later Use the Hazen-Williams and Manning formulas and compare the results. 

Among the many empirical formulae for friction losses that have been proposed that of Williams and Hazen has been most widely used. In a convenient form it reads ... 

Ricketts, A.T. (1934). Diagram for the solution of problems by Williams and Hazen Formula for discharge of pipes. Washington DC. 

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