# Hazen william Vs Darcy (pipe sizing)

by firavia
Tags: darcy, hazen, pipe, sizing, william
 P: 136 Nobody wants to help?
 P: 86 firavia how r u ?? well in this case you will make normal calculations till you reach the point of the branched system T and then you will study for single pipe each time and you will get the head losses but u must know both head losses are the same because your pump dischargin to atmospheric pressure
 P: 136 Hazen william Vs Darcy (pipe sizing) Thank you for your answer , what if I have 2 other branches , the operation get more complicated if I want to apply bernoulli equation for each branch + the common line , but if I use hazen william flow chart to estimate the diameter of each branch according to the flow rate of each one it is not going to be accurate at all , cause how can I estimate a diameter by assuming a flow rate and a slope , usually this chart to determine the head loss in a pipe when we have the diameter of each pipe and the flow rate , but in the case of pipe sizing I dont think it works cause we are assuming 2 values out of 3 am I right ? if yes is there any other method for pipe sizing ?.
 Sci Advisor HW Helper PF Gold P: 2,907 Hi firavia, There's a good pipe flow analysis paper I posted on this thread: http://www.physicsforums.com/showthread.php?t=234887 Take a look at page 15. It shows how to do piping networks there, but you'll need to understand how to do a single pipe run first. Bernoulli's is only used to determine changes in pressure due to velocity and elevation as shown on page 14. Basically, head loss due to flow restrictions are permanent losses that are unrecoverable, unlike the other terms in the Bernoulli equation. See if you can work through some of this and get some understanding on how to use the Darcy-Weisbach equation first. You may also consider getting a copy of the Crane Technical Paper #410. It's cheap but it's become a standard in the industry which has been built upon by others for one dimensional flow losses.
 P: 136 can we establish bernoulli equation + darcy equation added to it to calculate the head loss in the pipes as the following , according to the picture: P"A"/Guamma +V"A"square / 2.g = hEAD loss throug the main pipe and the pipe"BC" + elevation from the top of the tank to point B +V"C"^2/2.g -Head of pump . is the equation established above is correct ana balanced , if yes then the head loss in pipe BC is very slightly different thn the head loss in Bd because od the difference in discharge velocity at both pipes am I correct ? cause if we take the path ABD we the equation is : P"A"/Guamma +V"A"square / 2.g =P"D"/guamma "which is zero-atmospheric" +V"D"^2/2.g+ead loss all alon the path ABD + HEAD OF PUMP +elevation from the top of the tank to B , the difference in head loss of this path and the path of ABC is the difference in dynamic energy at discharge of the 2 pipes BD and BC , am I correct ? pleas confirm.
 Sci Advisor HW Helper PF Gold P: 2,907 Right, the outlet velocity will affect the overall dP slightly.
 P: 136 Thank you Q_Goest :)