Minimum Pipeline Flow
Minimum Pipeline Flow
(OP)
I am designing a device that uses the energy from the flow velocity in a pipeline to function. So I need the forum members to tell me what you use as the minimum practical pipeline flow velocity. This device may be used in mainline and plant environments so I would like the full range. So far my device works down to 10 fps but it is more efficient as the velocity increases.





RE: Minimum Pipeline Flow
RE: Minimum Pipeline Flow
I would think that in most cases, the minimum flow velocity would be zero. The minimum velocity is usually not the design criteria, and any given pipeline will be shut down at some time or another.
It might help to indicate your application more clearly. Liquid? Gas? Water? Petroleum? Steam? 1/2" pipe? 120" pipe?
RE: Minimum Pipeline Flow
For gas lines, I'm now using 3 m/s as the "minimum" design conditions in gas lines.
David
RE: Minimum Pipeline Flow
I am still welcoming any more replies!
RE: Minimum Pipeline Flow
The equation is Q=7.3*D^2.56*K^1.84 where Q is in GPM, D is inside diameter of standard iron pipe of 2 to 6 inches diameter and K is fraction of ID under fluid from 0.2 to 0.6. I ran some numbers for several pipe diameters in and out of the ranges specified and got results for a near 12 inch ID pipe that seemed plausible from my experience with reactor coolant pumps and piping. For 2, 6 and 12 inch IDs the equation results for K=1.0 are Q=43.05, 716.79 and 4226.95 GPM with respective full-flow velocities of 4.40, 8.13 and 11.99 fps. I can't offer anything reliable at this time on how to get in-fluid (not area averaged) velocities for partial fill fractions but it looks like a possibly simple circular segment geometry problem. Gas-water flow technology may provide an answer to the part-filled pipe orientation problem.
RE: Minimum Pipeline Flow
liquid flow: 10 ft/sec max. unless specific short uses and 7 ft/sec for reasonable economic sizing (pipe costs vs. pumping costs).
vapor flow: 100 ft/sec max.
RE: Minimum Pipeline Flow
BenThayer: Thank you for the maximum flow Rules of Thumb but I am actually concerned with minimum velocities. If you can forward me that information it would be most helpful.
RE: Minimum Pipeline Flow
A "usual" range would be 5 to 8 fps, with velocities significantly higher not uncommon. I would say that at the low end it would not be uncommon to see some lines operating at 3 fps. Obviously one could encounter velocities less than that, but not likely.