Flow velocity through pipe
Flow velocity through pipe
(OP)
Hi,
This is a relatively simple one I believe, but I have not had to do it before.
I am trying to work out what the velocity will be through a 150mm pipe which is 45m long and has an RL difference of 5m from top to bottom.
The pipe is pressumed full with 100mm of head above the top of the pipe. The pipe is a drain pipe which will be used to drain coal spillage (Slurry). I wont to make sure the pipe is the correct size.
I believe the Bernoullie equation can be used for this? V=Sqrt(2gh)? how do I take into account friction loss?
The only pressure is that of the small static head (100mm on the pipe at the top). I am assuming the pipe will be full.
This is a relatively simple one I believe, but I have not had to do it before.
I am trying to work out what the velocity will be through a 150mm pipe which is 45m long and has an RL difference of 5m from top to bottom.
The pipe is pressumed full with 100mm of head above the top of the pipe. The pipe is a drain pipe which will be used to drain coal spillage (Slurry). I wont to make sure the pipe is the correct size.
I believe the Bernoullie equation can be used for this? V=Sqrt(2gh)? how do I take into account friction loss?
The only pressure is that of the small static head (100mm on the pipe at the top). I am assuming the pipe will be full.





RE: Flow velocity through pipe
Q = (1.486/n)*A*(R^2/3)*S^0.5
Where: Q = flow in cfs
A = Area in sq ft
R = hydraulic radius in feet
( for a circular pipe R = D/4 )
S= slope of the hydraulic gradeline in feet/foot
For a standard galve pipe what would be the friction feet/100ft?
RE: Flow velocity through pipe
Assuming the pipe will be full is a risky assumption. Take a look at thread124-177112: Full pipe min flow calculation for that equation.
I'm not sure you have Manning copied down right, but I'm on the road and don't have my books. You might also look at Darcy Weisbach.
David
RE: Flow velocity through pipe
This is a common problem in the sewage piping sector. Through years of experience they have determined the minimum slope required to make the piping self-cleaning. If you have a non-pumped system you are in the same situation.
Somehow you will need to determine the self-cleaning slope and velocity. This is not something I have done myself, so I cannot guide you. Once you have this, and you know your average and peak flows, you can determine the pipe size required. If you have insufficient slope, or you have low points in the piping, it will just be a matter of time until the pipe blocks.
Katmar Software - Engineering & Risk Analysis Software
http://katmarsoftware.com
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RE: Flow velocity through pipe
I never would have guessed.
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