Piping System Resistance Curves

[ApertureScience]

Looking to calculate the system resistance curve of a piping system that splits to different processes. The required flow rates and pressures are known at the endpoints. What is the method for determining the system resistance curve at the points shown in the attached sketch?

 

[317069]

find out the highest pressure drop path, then this will be the system resistance.
system resistance curve is the pressure/flow relationship same as the pump curve.
how to calculate it, fluid mechanic books explain it in easy way. it is available online, by google or any in school library

 

[SAK9]

The easy way to plot the curves for a piping loop is to input the range of expected flow rates into an excel sheet along with the pressure drop formula(Darcy/HW)which will generate the corresponding pressure drops.

 

[BronYrAur]

I'm not exactly sure what you are asking? Are the boxes in your sketch pumps? I guess to just answer your question, the formulas mentioned above are correct, but B&G makes a "wheel" that you can use. I have never compared it to the formulas, but i assume it is close. You set the wheel at one operating point (which you list on the sketch), then you read the system head loss for other flow rates. You can plot the system curve from that.

 

[Artisi]

What are the "boxes" pumps, valves, filters ?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[ApertureScience]

I should have been a bit more detailed on the sketch. The boxes are just to represent valves and equipment upstream of the processes that the water is being delivered to. The pump will be located on the left side of the sketch. The method for getting the resistance caused by the equipment and valves is known, as is the method for the pipe resistance for each segment of pipe. But, when the pipe is branched, I don't know how the developed head is calculated, or how the resistance curves at specific points in the process are calculated.

 

[Drazen]

though i don't know what do you want it for, you can make resistance curve for each branch by calculation pressure drops along whole path, from main pump up to the point of consumption.

you can imagine main pipes, just for sake of understanding, as bunch of parallel pipes, each having flow which equals branch flow, all with the same pressure drop. that means your branch curve will have total pressure drop of all pipe segments up to the consumption point, and flow that equals branch flow. this data together with geodetic height are sufficient to make system curve.

if you have only central pump, you don't need system curves other than total curve; difference between branch path pressure drop and index path pressure drop gives you balancing pressures per branch.