Pipe diameter and Pressure loss relation 1

[vij36]

Dear All,

I am trying to find the relation between Head loss and the pipe diameter.
Is the Hazen Williams formula is suitable for this purpose?

Currently we have 2.5" pipe and want to replace this with a new 3" to have less Head loss.

Could please throw some light on this.

Thanks,

 

[LittleInch]

Try this

https://petrowiki.org/Pressure_drop_evaluation_along_pipelines

The change in head loss for the same flow rate is about d/D^5

So about 0.4 to 0.5 of the current head loss

Make sure you use ID not nominal size.



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Also: If you get a response it's polite to respond to it.

 

[vij36]

Thank you for the quick reply.

One more thing i want to bring up here. What effect will be there on the head loss of we T - joint a lower dia pipe with a higher dia pipe ? The intention is to avoid laying a new pipe and make use of the existing pipes.

 

[katmar]

The factor of 5 applies to turbulent flow, which is usually the case in industrial piping. For laminar flow the factor is 4. You could use Hazen-Williams or Darcy-Weisbach to do the analysis for turbulent flow, but only Darcy-Weisbach (together with the Colebrook equation or Moody diagram for the friction factor) for laminar flow.

If you put multiple pipes in parallel the flow rate in each will decrease and the pressure drop is (roughly) proportional to the square of the flow rate.

In using these rules of thumb it is good to first sort out in your mind what parameter is being kept constant. For example, as you change the diameter do you want to know how the pressure drop will change for a constant flow rate, or do you want to know how the flow rate will change while the pressure drop remains the same.



Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[vij36]

In using these rules of thumb it is good to first sort out in your mind what parameter is being kept constant. For example, as you change the diameter do you want to know how the pressure drop will change for a constant flow rate, or do you want to know how the flow rate will change while the pressure drop remains the same.

Thanks for the help. I would like to know how the flow rate changes keeping the pressure drop as constant.

I am really new to these subject matter. Our existing MEP technician is on a medical emergency and there is this sudden task come to me.

Basically I am trying to sort out a very fundamental thing as "how to know for a typical head what would be the appropriate diameter pipe which will result in optimal flow rate with less frictional losses".

Thanks,

 

[Compositepro]

A very rough rule of thumb for low viscosity fluids is that you want to stay below 10 ft per second velocity. For gas stay below 100 ft/second. For energy savings, cut those numbers in half.