Max Flow through pipe

[alberto12]

I am confused about flow concept and would appreciate your help.

I have a 2" pipe going to a tank from another 10" line. The pressure at the tie in point is 5 barg. Whats the max amount of water that will flow through pipe

 

[zdas04]

Flow rate is a function of dP, pipe size, pipe length, and pipe roughness. You didn't say what pipe material or how long the 2-inch was. If it is less than a meter long and some really slick pipe then the flow rate is pretty high. If it is 2 miles of old, scaly cast iron then the flow rate is noticeably less.

David

 

[cheute79]

you don't give much information. Aside from pressure drop, pipe size, length, and surface roughness, it's also an issue of configuration off the 2" off of the 10". A branch off the T (probably what you have), will have more pressure drop, and so usually less flow, but driven also by the pressure in the 10".

If one is to design a system for flow, optimal velocity is around 7 ft/sec, or 2.1 m/s. That would mean around 75 gpm. You would be hard pressed to get more than about 100 gpm in the 2 inch line, and virtually assured to be at least 50 gpm.

 

[devaxrayz]

As explained in earlier post by zdas and cheute, the water flow is function of several factor.

The concept is: the pressure drop (depends on flowrate) of water flowing in the pipe will be equal to available delta pressure in the system. The calculation to calculate the pipe system capacity itself is an iterative effort.

For example:
your tie-in point pressure : 5 barg
your tank pressure (at the point the water enter): 2 barg
your available delta pressure : 3 bar

You then develop your pipe model, incorporate all the length, fitting, valve, pipe type (roughness), pipe size etc. Then start the iterative process by trial and error input the flowrate and calculate the pressure drop. The flow that give you pressure drop equal to 3 bar then is the capacity of your pipe system.

The capacity of your pipe system can be change if your pipe condition change (change in pipe roughness), your tank pressure change (change in available delta pressure) etc...

hope this help

-rayz-

 

[VikingUK]

David, you state "Flow rate is a function of dP, pipe size, pipe length, and pipe roughness." is there one calcualtion that ties all these factors in ? eg can I calculate dp if I know the other variables ?

 

[Vaione]

Yes you can figure it out if you know dp. go to RC-6 and you will find that equation wich will help you to find other factor.

http://www.psig.org/papers/2000/0112.pdf

this might help u.

 

[Latexman]

RC-6?

Good luck,
Latexman

 

[Rickyherb]

Alberto:

I would do as devaxrayz put it, with further addition. I think you need to analyze this problem abit more than the simplistic form of looking at max flow. You need pipe characteristics,i.e material of pipe, roughness, length to point of delivery, types of bends if any to delivery point, types and number of valves (orofices, venturi etc as these have different delta-P's in addition to the pipe length delta p) and lastly wether the point of delivery is at the same elevation or not from supply). So max flow of water- going where? can be answered fully with your analysis of complete flow diagram.

 

[Zoobie]

I sincerely hope Alberto gets the help that he needs. Forgive me for being suspicious but the problem statement reminds me of some of my old fluid mechanics homework assignments (from what I can recall 15 years ago).