I am interested if anyone is aware of any research or article that provides guidance on the lowest water velocity that is acceptable for performing a C-factor calculation for a 6” pipe?
I am curious if there is a lower flow velocity where the Hazen-Williams equation may not be valid. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe
7 Comments
Dan Wilder
5/11/2020 09:08:52 am
Actually, HW would be your "Go-To" until either higher velocities or different viscosity's are being used. Below are some good articles to read.
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Mike
5/11/2020 10:28:19 am
Why would you want lower velocities? As understand it, H-W is for laminar flow and lower velocities would be laminar flow.
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Ivonn
5/11/2020 11:24:01 am
I agree with you, H-W is for laminar flow, so if He/She had low velocity won't be a problem
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Ivonn
5/11/2020 10:59:45 am
In NFPA 13 Ed.2019 include a new statement in the section 27.2.1.4 says : the velocity of water flow shall not be limited when hydraulic calculations are performed using the Hazen - Williams.
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SK
5/11/2020 04:15:33 pm
As far as my knowledge, none of the NFPA provides any limitation in velocity criteria for fire water system, sometime rather these limitation comes from piping materials as guidance...e.g. Metallic pipe, 3.0 m/s or non-metallic pipes 5.0 m/s...
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Mark
5/11/2020 11:46:49 am
Maybe I am not reading the question correctly but the C Factor is defined in NFPA 13 based on pipe material?
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Mike
5/12/2020 01:00:49 am
C factor is basically a coefficient of roughness that can change over time. Easily determined in existing systems if all other factors are known.
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