Single pipe equivalent for parallel pipe 3

[WYeng]

I'm having a brain freeze right now....

I've got two pipes in parallel - same diameter, roughness, and one slightly longer than the other.

In a model I'm working on, I want to reduce the two pipes to a single pipe. I'm using Hazen-Williams to find the equivalent pipe diameter.

Should my resulting pipe diameter be larger or smaller than the original....?

 

[hydrae]

WYeng
It should be larger that the original and be slightly less than the root of the sum of the squares of diameters.
But having different lengths turns the solution into an iterative calculation for each flow...
Hydrae

 

[JStephen]

I would think the actual size would also depend on the flow rate, too?

 

[Ballintoy]

Your equivalent pipe can actually be any diameter but the length will change.

Assume a headloss from Point A at the beginning of the loop to Point B at the end. Determine the flow in each pipe for the assumed headloss. Add the two flows to get a total. Using the calculated flow, whatever diameter you choose, and the assumed headloss, solve for the length of the pipe.