What is the max gpm you can get with a 6” dr 18 underground?
We had a flow test of static 68 psi residual 48 psi flowing 1950 gpm. With 3111 gpm @ 20 psi. Some one is telling us the max gpm is 800 gpm. How is this possible? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe
7 Comments
DW
10/23/2019 08:39:02 am
The easiest way to explain available flow is using Freeman's formula. Q=29.84*c*(d^2)*sqrt(p) where p is the pitot pressure and c is a coefficient related to the outlet. This formula was likely used to calculate the 1950 gpm you were given from your flow test.
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CRB
10/23/2019 09:07:26 am
The 800 gpm might be coming from the manufacture specification.
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NK
10/23/2019 10:30:27 am
NFPA 291 is the Recommended Practice for Flow Flow Testing and Marking of Hydrants. Chapter 4 probably has the information you are looking for.
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Cliff
10/23/2019 12:23:10 pm
Sounds like someone is confusing the flushing requirements with the flow capacity. NFPA requires you to flush 6" underground pipe by flowing a minimum of 880 gpm.
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Kelly
10/23/2019 01:49:51 pm
Came here to say this. I think that is probably where it came from.
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Dennis R
10/28/2019 10:16:10 am
AHJ's around here get this confused all the time!
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Franck Orset
10/30/2019 10:42:04 am
Fully agree with what was said.
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