There is a simpler equation - D = [C0*Q*n/Sqrt(S)]^(3/8) that should be used, in my opinion. Also, as others have noted, the manning's value is 0.013 for plastic.
ncees pe hb 1.1, p. 3, 328-329. used hazen-williams to get a close-enough answer. anyone thinks this was dead wrong ? here are my numbers: . q = 1.81215 cfs . c = 150 . s = 0.004 solve for d. d = 0.7966' = 9.56" = 10.0". always round up pipes hence the 10". (B)
I would not say it is dead wrong as the results from using the hazen-williams equation versus manning's equation are around the same. Although, in industry, we typically don't use the hazen-williams equation for sizing sewer pipes, therefore I would use the manning's equation. The PE exam is the "profession & practice of engineering", so you would need to use the engineering theory mixed with what is typically done by most engineers in the practice of the profession.
There is a simpler equation - D = [C0*Q*n/Sqrt(S)]^(3/8) that should be used, in my opinion. Also, as others have noted, the manning's value is 0.013 for plastic.
Hello on PDF pg 346 for the PE plastic is listed as " n = 0.013 "
With corrected n = 0.013 value I got d = 11.064 in
n=0.010 if pipe was PVC but problem statement states that pipe is plastic. Per the table, n=0.013. Please revise video.
ncees pe hb 1.1, p. 3, 328-329.
used hazen-williams to get a close-enough answer. anyone thinks this was dead wrong ?
here are my numbers:
. q = 1.81215 cfs
. c = 150
. s = 0.004
solve for d.
d = 0.7966' = 9.56" = 10.0".
always round up pipes hence the 10". (B)
I would not say it is dead wrong as the results from using the hazen-williams equation versus manning's equation are around the same. Although, in industry, we typically don't use the hazen-williams equation for sizing sewer pipes, therefore I would use the manning's equation. The PE exam is the "profession & practice of engineering", so you would need to use the engineering theory mixed with what is typically done by most engineers in the practice of the profession.