# Use the Hazen-Williams equation to compute friction loss with C-120- A.docx

4. Feb 2023
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### Use the Hazen-Williams equation to compute friction loss with C-120- A.docx

• 1. Use the Hazen-Williams equation to compute friction loss with C=120. Account for minor losses. All pipes and fittings are 6-in diameter. Determine the flow (cfs) from A to B. Solution V=KC(D/4)^0.63 * S^0.54â€¦â€¦â€¦.(1) - hazen-william equation Where S=Hf/L and Q=V*A , A=(/4)D^2 From bernouliâ€™s equation, 100+100=V^2/2g+Hf+(0.4*V^2/2g)+(0.8*V^2/2g)+(0.8*V^2/2g)+ (1* V^2/2g) 200= V^2/2g(1+0.4+0.8+0.8+1+Hf) 200*2*32.2= V^2(4+Hf)â€¦â€¦â€¦.(2) Given, C=120, D=6in=0.5ft L=700ft and take K=1.318 Substituting above values in (1), we get V=1.318*120*(0.5/4)^0.63 * (Hf/700) ^0.54 V=1.241*(Hf)^0.54 Squaring above equation, V^2=1.54*(Hf)^1.08 Approximating the power of Hf in above equation from 1.08 to 1.00, inorder to reduce the complexity in calculations,
• 2. V^2=1.54*Hf.............(3) Put (3) in (2), we get 12880=1.54*Hf(4+Hf)=6.16Hf+1.54Hf^2 On solving above quadratic equation, we have Hf=89.4747ft, therefore V=11.738ft/sec Q=A*V=( /4)0.5^2*11.738=2.30cfs If Hf is calculated by trial and error method, it is found to be, 90.5ft, and V=14.136ft/sec Q becomes 2.775cfs