Flushing Water Mains - Scouring Velocity
Flushing Water Mains - Scouring Velocity
(OP)
What velocity would I look for to achieve a proper scouring in a water main? 2.5 ft/s? 5 ft/s?
Any links?
Thanks!
Any links?
Thanks!
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Flushing Water Mains - Scouring Velocity
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Flushing Water Mains - Scouring VelocityFlushing Water Mains - Scouring Velocity(OP)
What velocity would I look for to achieve a proper scouring in a water main? 2.5 ft/s? 5 ft/s?
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RE: Flushing Water Mains - Scouring Velocity
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A typically flushing velocity of 3.0 to 3.5 ft/ sec will normally suffice.
RE: Flushing Water Mains - Scouring Velocity
For example an 8-inch main at 3.5 fps will give you a flowrate of 548 gpm, which is fairly easy to get rid of. For an 18-inch main, 3.5 fps will give you a flowrate of 2775 gpm, which becomes more difficult to dispose of.
It is not always practical to get scouring velocities is larger pipes and you may have to live with the fact that there may be some sediment in the pipe. This is why it is very important that the pipes are kept as clean and free of debris as possible during construction or repair.
RE: Flushing Water Mains - Scouring Velocity
RE: Flushing Water Mains - Scouring Velocity
Minimum flushing velocity per AWWA C651 is 2.5 fps so 3.5 fps is a good target for public mains. There is a table in the standard that indicates flows needed for 2.5 fps and the size/number of taps needed at a pressure of 40 psi.
For private fire mains, flushing velocities may potentially need to be 10 fps or higher (about 1,560 gpm vs 400 gpm for 2.5 fps).
No direct links, but you can do a search for "AWWA C651 Flushing" and find specifications or guidance documents referencing C651 for the stated flushing requirements. For private fire lines, NFPA 24 is available for viewing if you register (free) at the NFPA site.
RE: Flushing Water Mains - Scouring Velocity