# I need to select a suitable diameter for my pipes

## Main Question or Discussion Point

Hi guys,

Please help me out, I have a project here I need to design a pipe network system using Hardy Cross method.

I have drawn my pipe network and done my distribution of the flow rate according to the give discharge. but now I'm not sure which method I should use in selecting pipe sizes.

Pleasr help me out.

Regards
Young.Eng.SA

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What is it that you are trying to optimize? Cost, volume, efficiency, weight? The only fluids related parameters pipe size effects is the pressure loss (head) in the piping system and the fluid velocity. All these relationships can be found using Moody's diagram and models such as the Hagen-Poiseuille equation.

http://en.wikipedia.org/wiki/Hagen–Poiseuille_equation

Surely any reasonable size will do?

The Hardy Cross method is really an iterative method for solving a system of linear simultaneous equations.

Hi,

I was also thinking of considering Hardy Cross. But I'm only given a flow rate of 15000 cubic meters and I believe I have to make assumptions for the selection of diameters but again how far in assumptions should I get with the above flow rate?

Also can you guys tell me: what are the properties of helium gas at 900 degrees celcuis. I believe this is an inert gas that can be solidified at high pressures

Hi,

I'm looking on both volume and cost only

Hi,

......Also can you guys tell me: what are the properties of helium gas at 900 degrees celcuis. I believe this is an inert gas that can be solidified at high pressures
IIRC, that's incorrect. I don't even think there's a industrial use for liquid helium.

Helium does not solidify or liquefy outside of extreme lab environs. At least on earth.

You want to size the pipe so that your velocities are fairly low. If its something generic, size it to about 7 ft/s. Dealing with gas is a little more complicated as its compressible, really depends on how much volume you want at your outlet