Plotting William Hazen and Friction loss equations
Plotting William Hazen and Friction loss equations
(OP)
I don't know if this is the right post for this question.
I have used the Q to the 1.85 exponent semi-log graph since the 1970's to plot as straight lines the above equations when checking water supply and fire sprinkler adequacy as it is the acceptable method by municipalities and insurance companies.
Yet, I never questionned, until now, the use of the semi log graph paper instead of the log-log graphing paper which should be the choice for these two equations. Can any one explain why the semi log paper is acceptable?
I have used the Q to the 1.85 exponent semi-log graph since the 1970's to plot as straight lines the above equations when checking water supply and fire sprinkler adequacy as it is the acceptable method by municipalities and insurance companies.
Yet, I never questionned, until now, the use of the semi log graph paper instead of the log-log graphing paper which should be the choice for these two equations. Can any one explain why the semi log paper is acceptable?





RE: Plotting William Hazen and Friction loss equations
But why bother - in the 1970's when working with a slide rule it made sense to plot two points and draw a straight line. Now the simple solution is to stick the equation into a spread sheet and plot the curve to whatever scale you want ??
RE: Plotting William Hazen and Friction loss equations
RE: Plotting William Hazen and Friction loss equations
RE: Plotting William Hazen and Friction loss equations
The Darcy – Weisbach Equation is usually stated as :
EPANet2 provides the following Roughness Coefficients for New Pipe
Material H-W C(unitless) D-W e(millifeet) Manning's n(unitless)
Cast Iron 130 - 140 0.85 0.012 - 0.015
Concrete 120 - 140 1.0 - 0.012 - 0.017
Galvanized Iron 120 0.5 0.015 - 0.017
Plastic 140 - 150 0.005 0.011 - 0.015
Steel 140 - 150 0.15 0.015 - 0.017
Vitrified Clay 0.013 - 0.015
"
RE: Plotting William Hazen and Friction loss equations
I believe that the error is not significant and the graph is simplified. I'll have to work out some past flow tests to see if this is right.