Pressure Drop-Sloped Pipe

[RJB32482]

Hello,
When I take into account a downward sloped pipe (for example 10 ft of pipe sloped 45 degrees down, no fittings, no valves) for pressure drop, do I just add the pressure drops due to elevation change and pipe length? Or is there another friction factor involved in the calculation?

Thanks

 

[Latexman]

Ignore the fact that some pipe is sloped, and use the Darcy-Weisbach equation for frictional losses for the pipe and fittings in the entire system, including the length of pipe that is sloped (that you are ignoring that it is sloped). Then use the Bernoulli equation to correct for mechanical energy differences due to elevation (here's where you account for the elevation change of the sloped pipe) and velocity changes.

Good luck,
Latexman

 

[katmar]

Just a word of caution - any downward flow (whether sloped or vertical) should always be checked to see in what regime you are working. If the flow is insufficient to fill the sloped pipe the calculation is completely different. This affects mainly what I term the "pressure recovery" and what Latexman has called, probably more correctly, "mechanical energy differences due to elevation".

 

[MortenA]

There is no "special pressuredrop" added for sloped pipeing (assuming single phase flow). However the head that follows from the elevation change (up or down) cannot be ignorde. The elevation change must however be the "final". So if you first go down and then back up then only the final change should be considered.

Best regards

Morten