Effects of Increasing Header Pipe Diameter in Water Distribution

[balotpinoy]

kindly help me with this one.

im trying to find out what is the effect if i increase the diameter of my header pipe in a water distribution line.

i think pressure at the discharge pipe will decrease. if so, i don't know how to justify it.

tnx in advans.

 

[Travis_King]

Assuming the same volumetric flow, you will have less fluid velocity. Pressure changes in proportion to the square of the velocity, so you will have less pressure with a lower velocity.

But if you open it up and the system allows more volumetric flow, you may see the same velocity/same pressure.

 

[balotpinoy]

kindly see attached diagram.. thank you..

each pump has a capacity of 2,200 gpm at 180 ft head..

 

[balotpinoy]

kindly see attached diagram.. thank you..

each pump has a capacity of 2,200 gpm at 180 ft head..

 

[Travis_King]

I assume they are centrifugal and not positive displacement?

 

[balotpinoy]

yes.. centrifugal pumps..

 

[Travis_King]

If your header discharge are still the same, I don't think you should see much of a difference. The pressure within the header will decrease so you'll get the benefit of the friction losses there, but you'll probably lose that at the discharge lines due to the reduction and change of flow velocity. Bottom line, if the discharge lines are the same, then you should still be about the same head.

What is the desired result?

 

[balotpinoy]

im just trying to evaluate the difference between having a 10 or 20 in diameter header.

the first set up was 10 inches diameter header and it was changed to 20 inches due to unknown reasons.

i just want to know if that change actually help in terms of the discharge pressure.

thank you again.