Rate of flow from a pipe drain
Rate of flow from a pipe drain
(OP)
I am trying to calculate rate of flow from drain of pipe. pipe size is 6" about 100 feet long, and drain size is 3/4". It is a gravity flow and medium is water. there is a large piping system which we have to drain for shut down, we have to calculate the time it will take to drain that.
Thanx, Zalamay
Thanx, Zalamay





RE: Rate of flow from a pipe drain
RE: Rate of flow from a pipe drain
RE: Rate of flow from a pipe drain
In gravity fed pipe all the potential energy (available head) is dissipated as pressure drop.
You can use D'Arcy Weisbach equation for friction losses, running some iterations with different flow rates, until results converge. You have also to account for entrance and exit losses as pointed out above.
RE: Rate of flow from a pipe drain
RE: Rate of flow from a pipe drain
RE: Rate of flow from a pipe drain
RE: Rate of flow from a pipe drain
Have a look at this thread
http://www.eng-tips.com/viewthread.cfm?qid=289494
RE: Rate of flow from a pipe drain
Thanks once again
RE: Rate of flow from a pipe drain
Do not forget two issues:
- The role of the pipeline slope (steeper--> more discharge)
- To control the maximum flow velocity during draining
Depending on your pipe slope and drain velocity, you might need to use an orifice at the discharge to limit / control the drain velocity.
Then I would like to point out that the correct direction during the design phase is to size the drain to reach a certain acceptable draining time. you can not wait 3 days to drain 5 km of you pipeline. So normally you size the drain valve to achieve a certain draining time. However you are doing it vise versa here, looking for the drain time based on the size of the drain valve. I understand this could be a case dealing with an constructed pipeline.
Once, I had written an Excel worksheet to calculate the draining time based on the pipeline diameter, length and slope. Unfortunately I cannot find it in my archive at the moment. While I keep searching for it, you might find this article of particular interest:
Procedures for Calculating Drainage from Pipeline
Hope this would help.
RE: Rate of flow from a pipe drain
Thanks