Full pipe min flow calculation
Full pipe min flow calculation
(OP)
How do you calculate the min. flow needed to keep full pipe flow
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Full pipe min flow calculation
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Full pipe min flow calculationFull pipe min flow calculation(OP)
How do you calculate the min. flow needed to keep full pipe flow
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RE: Full pipe min flow calculation
RE: Full pipe min flow calculation
I believe what dearman is referring to is the transition point wherein a partially full gravity flow line is asked to handle additional flows until the point where it becomes totally full. There is a name for this point, which I have forgotten, and there is a formula for determining the associated flowrate. Hopefully a fellow reader can supply this missing information.
Doug
RE: Full pipe min flow calculation
This will keep a horizontally orientated pipe (with no pockets or change in the vertical direction) full of liquid all the way to discharge.
I know someone will ask me where this comes from and I do have the reference, but not with me at this time. I'll have to post the reference tomorrow (East Coast, USA) unless someone else has it posted by then.
RE: Full pipe min flow calculation
http://www.freecalc.com/selffram.htm
RE: Full pipe min flow calculation
RE: Full pipe min flow calculation
For a vertical (or near vertical) pipe you should use Darcy-Weisbach with a pressure drop gradient equal to the static height. For a given height the static head is density x gravity x height and if the friction head exactly matches this the pipe will remain full and there will be a zero net pressure gradient. If the flow is such that the friction head is less than the static height the pipe will partially drain, and if the flow is such that the friction head exceeds the static head the pipe will over flow. This analysis will apply if the pipe entrance is "open" like a drain. If the pipe entrance is always flooded then you should look for the syphon point, which will be at a slightly lower flow rate than the zero pressure gradient analysis gives.
For a truly horizontal pipe I would expect the critical value to depend on the length of the pipe. I cannot recall the equation suggested by pleckner, but it looks like it could be a useful rule of thumb. Presumably those gpm are USgpm and the ID is inches and the fluid is water?
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Full pipe min flow calculation
Druand, A.A & M. Marquez-Lucero, "Degermining Sealing Flowrates in Horizontal Run Pipes", Chemical Engineering, March 1998.
Another source is:
Sandler, H.J. & E.T. Luckie-wicz, "Practical Process Engineering", McGraw Hill, 1987
And as katmar stated, the diameter is in inches and the flow is in USgpm.
RE: Full pipe min flow calculation
Thanks for following up
Good effort
RE: Full pipe min flow calculation
RE: Full pipe min flow calculation
RE: Full pipe min flow calculation
Regards
RE: Full pipe min flow calculation
RE: Full pipe min flow calculation
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Full pipe min flow calculation
Per my previous post, what if a non-condensible gas comes out of solution?
Regards
RE: Full pipe min flow calculation
I assumed the OP was interested in a typical scenario, since no further details were given by him, other than he wanted to avoid 2-phase flow. The thread managed to stay within those parameters, until you brought up the gas leaving solution in your post, however, since 2-phase flow was to be avoided and the OP did not mention any particular problem with that phenomenon, I didn't think it relevant to address it further.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Full pipe min flow calculation
The orig question was --How do you calculate the min. flow needed to keep full pipe flow.
Can a typical liquid have dissolved gases? Does a gas coming out of solution not apply?--or perhaps my question is to complicated?
Regards
RE: Full pipe min flow calculation
Certainly there are many typical liquids that could have that flow characteristic you describe, oil with 5% air for example, or heating water to steam in a long pipe, but I didn't see where any of those conditions formed part of the problem as proposed by the OP.
My advice is, "don't make a problem's solution more complicated than it has to be solve the question at hand".
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Full pipe min flow calculation
This is the design equation I use:
If {Q/d}^2.5 >= 10.2 The pipe is running full.
If {Q/d}^2.5 < 10.2 The pipe is partially filled.
where,
Q [volumetric flow rate 'gpm']
d [pipe diameter 'in']
This is located in C. Brannans handbook.
M. Felzien
RE: Full pipe min flow calculation
The equation you have given here looks similar to that presented earlier by pleckner, but would give very different results to his because in your equation the Q is raised to the power of 2.5, but it was not in pleckenr's. Does Brannan give references, and are they the same as those pleckner gave?
pleckner do you have any comment on this? It is a useful looking equation that I would like to add to my list of tools, but this discrepancy worries me and I do not have the original references.
regards, Harvey
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Full pipe min flow calculation
RE: Full pipe min flow calculation
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Full pipe min flow calculation
You are right as usual. I have checked the original article in ChE and pleckner's version is the right one.
Best wishes
RE: Full pipe min flow calculation
regards
Harvey