## how to calculate flow-rate and drop pressure on branch pipe.

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sofiudin
Posts: 2
Joined: Wed Mar 17, 2010 4:36 pm

### how to calculate flow-rate and drop pressure on branch pipe.

Hello guys..
I've read theory about how to calculate drop pressure on serial pipe and parallel pipe(looping) design. But, i didn't found how to calculate flow-rate and drop pressure on branch pipe design (without looping). Can u help me?
Thanks before..

Posts: 365
Joined: Mon Feb 08, 2010 7:47 pm

### Re: how to calculate flow-rate and drop pressure on branch pipe.

Step 1. It is similar like in loop, but you have to know (or make an assumption) the pressure (head) on the start of the branch and at the end of the branch and based on pressure (head) change from start to the end of branch you can calculate the flow.

Step 2. Now that calculated flow is influencing the pressure on the start of the branch, because flow in connecting pipe, so it (pressure, head) has to be recalculated based on the flow through the branch and other flow that goes by (total flow is the flow through all branches).

When you have that new pressure on the start of the branch, go back to step 1. and calculate flow again, go to step 2, and loop until the pressure change is small enough.

One day I will make/upload calculator for it but until then.....
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sofiudin
Posts: 2
Joined: Wed Mar 17, 2010 4:36 pm

### Re: how to calculate flow-rate and drop pressure on branch pipe.

I've read your explanation repeatedly. Overall, i know what you mean. But i'm still not exactly understand the step by step. Can you exlpain to me again, including illustration (use picture). If you explain with illustration i hope i will more understand.

Your solution (step by step) is similar with Newton-Raphson method. Is that true?
Thanks.. Posts: 365
Joined: Mon Feb 08, 2010 7:47 pm

### Re: how to calculate flow-rate and drop pressure on branch pipe.

Here is the illustration: 1. Now, to calculate flow in pipe A-B you need to know pressure on point B. I would make assumption as it is 5 bar.
Flow rate Q1 can be calculated now.

2. Calculate flow in B-C and B-D based on the same pressure of 5 bar in B. Flow Q2 and Q3 can be calculated.

3. Now calculate new value of Q1=Q2+Q3.

4. Calculate pressure in B based on Q1 in 4.

5. This new pressure in B should be used for step 2. - calculate flow in Q2 and Q3 ... etc.

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