How to calculate flow rate in a pipe system

THIS PROBLEM OF YOURS IS BASED ON CALCULUS ( MATHEMATCIS IN COLLEGE) UNDER TOPIC " CALCULATING RATE OF FLUIDS/ DEGRADING OF ITEM OR OBJECT". IF YOU HAVE HEAR OF DIFFERNTIAL EQUATIONS THIS IS WHAT I AM TALKING ABOUT AND IS RELATED TO YOUR PROBLEM.

KINDLY GO THROUGH MATHS BOOK OF 12 STD AND ABOVE AND LOOK FOR TOPIC RATE . THIS WILL HELP YOU/ OR YOU CAN SEARCH ON INTERNET IN GOOGLE RATE

HOPE THIS HELPS YOU

SAMIP

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If I understand correct, you are asking how to specify the valves and size them. Usually, it is the requirement of flow at certain point will define the valves that needs to be sized. For example: if flow requirement at certain point is 50 lph, then it means you can open upto valves with the pumps you have. Also, the pipes sizes will depend much of how many valves would be open at the same time.

You have to refer to the valves and/or pipes manufacturers to provide you the capacity of each valve and the friction loss. Make sure, the friction lost at each valves should not exceed 10% of the pump pressure.

Hope this answer your question.

If 2 pumps are running instead of one, one doesn't get twice the flow. The reason is that the system the pumps are connected to has a characteristic curve just like the pump characteristic curve. Where these two curves intersect is the operating point.

A full hydraulic analysis of the system is required to obtain the system characteristic curve. It can be done from first princiles, though alternatively, one can use some pressure gauges and some way of measuring and modulating the flow in the system.

If you install a few pressure gauges, the problem can be solved to some extent as follows.

1. Measure pump inlet and outlet pressure for each pump. Convert this deltaP into meters (if water at ambient conditions, you may use 1 bar = 10.21 meters). This is pump TDH (total developed head).

2. Then refer to pump curves and calculate the flow corresponding to the TDH. Add flow of each pump to calculate the system flow.

3. Take pressure reading at each delivery point and calulate pressure loss (deltaP) from pump duscharge to the delivery point.

4. Use darcy-weisbach equation deltaP = 4flv^2/2g. Depending on pipe material there are values for the f - friction factor (see Crane Technical paper or just google). From the data availabe so far you can now calculate v - pipe velocity.

5. Multiply the velocity with the pipe cross sectional area (pi/4 x ID^2) to calculate the flow.

6. You may cross check by adding the flow from each delivery point and compare to the system flow calculated in step-1. If the error is small, you got what you wanted!!! If not, go back and re-check.

There's even more to it than has been posted.

What are the differences in "altitude" of the pump outlets and the various discharge points? If the height difference is substantial, then you have another factor to include.

Like if you are pumping water and the branches are at different floor levels in a multi-story building.

As others have already suggested, you need to map the system and do the sums, since not only is the layout important, but also the pipe lengths and the pump "performance curves". (Maybe the 500lpm is at no pressure.)

What are the differences in "altitude" of the pump outlets and the various discharge points? If the height difference is substantial, then you have another factor to include.

I thought I did included on post #1, (forgotten) that but Engineering Power Tools program does.

Good catch though

p911