62 
BULLETIN 852, U. S. DEPARTMENT OF AGRICULTURE. 
Table 10. — Velocities, in feet per second, as computed by various formulas 
for given sizes of pipe with given friction heads. 
1 
Diam- 
eter 
(d). 
2 
Fric- 
tion 
head 
(S). 
Velocities, in feet per second 
by formulas. 
Scobey. 
Coefficient (C«). 
Williams-Hazen. 
Coefficient (C w ). 
Kutter. 
Coefficient (n). 
Moritz. 
Coeffi- 
cient 
(Cm). 
20 
Sco- 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
bey. 1 
0.267 
0.310 
0.345 
0.370 
90 
100 
110 
120 
130 
140 
0.014 
0. 013 
0.012 
0.0115 
0.011 
1.24 
1.31 
Ins. 
6 
6 
6 
Ft. 
2.0 
5.0 
9.0 
Ft. 
1.16 
1.83 
2.46 
Ft. 
1.35 
2.10 
2.85 
Ft: 
Ft. 
Ft. 
1.11 
1.84 
2.52 
Ft. 
1.24 
2.04 
2.80 
Ft. 
1.36 
2.25 
3.08 
Ft. 
1.48 
2.45 
3.36 
Ft. 
1.61 
2.65 
3.64 
Ft. 
Ft. 
1.01 
1.61 
2.15 
Ft. 
1.09 
1.73 
2.33 
Ft. 
1.24 
1.98 
2.68 
Ft. 
Ft. 
Ft. 
1.45 
2.37 
3.28 
Ft. 
1.53 
2.50 
3.47 
Ft. 
1.52 
2.52 
3.50 
12 
12 
12 
1.0 
5.0 
9.0 
1.26 
2.82 
3.79 
1.47 
3.28 
4.39 
1.63 
3.65 
4.89 
1.75 
3.91 
5.25 
1.19 
2.84 
3.89 
1.32 
3.15 
4.33 
1.45 
3.47 
4.76 
1.58 
3.78 
5.19 
1.72 
4.10 
5.62 
1.85 
4.40 
6.06 
1.22 
2.74 
3.70 
1.35 
3.02 
4.05 
1.48 
3.36 
4.50 
1.56 
3.54 
4.72 
1.65 
3.75 
5.00 
1.58 
3. 86 
5.36 
1.67 
4.08 
5.66 
1.62 
3.96 
5.48 
36 
36 
36 
0.2 
1.0 
5.0 
1.12 
2.51 
5.61 
1.30 
2.91 
6.51 
1.45 
3.24 
7.24 
1.55 
3.47 
7.77 
0.99 
2.38 
5.66 
1.11 
2.64 
6.30 
1.22 
2.91 
6.92 
1.33 
3.16 
7.55 
1.44 
3.43 
8.18 
1.55 
3.69 
8.81 
1.19 
2.76 
6.20 
1.34 
3.01 
6.74 
1.48 
3.31 
7.48 
1.53 
3.49 
7.85 
1.66 
3.73 
8.30 
1.39 
3.40 
8.33 
1.47 
3.59 
8.80 
1.35 
3.31 
8.08 
72 
72 
72 
0.2 
1.0 
2.0 
2.21 
5.00 
7.07 
2.40 
5.36 
7.58 
1.54 
3.68 
5.35 
1.71 
4.08 
5.94 
1.88 
4.49 
6.54 
2.06 
4.89 
7.14 
2.23 
5.31 
7.73 
2.40 
5.71 
8.32 
1.96 
4.46 
6.31 
2.12 
4.83 
6.86 
2.31 
5.27 
7.47 
2.43 
5.51 
7.80 
2.59 
5.79 
8.20 
2.26 
5. 52 
8.14 
2.39 
5.84 
8.59 
2.12 
5.19 
7.63 
96 
96 
96 
0.2 
0.6 
1.0 
2.67 
4.62 
5.98 
2.87 
4.91 
6.41 
1.85 
3.34 
4.41 
2.06 
3.72 
4.90 
2.26 
4.08 
5.38 
2.46 
4.46 
5.78 
2.67 
4.83 
6.37 
2.88 
5.21 
6.86 
2.39 
4.18 
5.40 
2.58 
4.51 
5.84 
2.81 
4.90 
6.34 
2.94 
5.11 
6.61 
3.07 
5.37 
6.95 
2.77 
5. 20 
6.77 
2.93 
5.39 
7.15 
2.56 
4.70 
6.26 
120 
120 
120 
0.2 
0.6 
1.0 

3.08 
5.37 
6.88 
3.30 
5.71 
7.37 
2.13 
3.85 
5.08 
2.37 
4.28 
5.64 
2.60 
4.71 
6.20 
2.84 
5.14 
6.76 
3.08 
5.57 
7.32 
3.31 
5.98 
7.90 
2.77 
5.82 
6.23 
3.00 
5.20 
6.73 
3.24 
5.65 
7.30 
3.38 
5.89 
7.62 
3.57 
6.18 
7.98 
3.24 
5. 96 
7.92 
3.42 
6.30 
8.36 
2.96 
5.45 
7.24 
144 
144 
144 
0.2 
0.6 
1.0 
3.45 
5.97 
7.71 
3.70 
6.40 
8.26 
2.39 
4.32 
5.69 
2.65 
4.80 
6.32 
2.92 
5.27 
6.96 
3.18 
5.75 
7.58 
3.45 
6. 23 
8.21 
3.71 
6.70 
8.85 
3.13 
5.43 
7.00 
3.37 
5.84 
7. 55 
3.65 
6.34 
8.18 
3.80 
6.61 
8.53 
3.99 
6.92 
8.93 
3.65 
6. 76 
S.95 
3.85 
7.13 
9.45 
3.33 
6.14 
8.15 
on formula for velocity in average wood-stave pipe; V= 1.62 D -65 H' 555 . (See Dept. Bui. 376. p. 7.) 
COMPARISON OF THE VARIOUS FORMULAS. 
For the reason that there are at least four distinct classes of con- 
crete pipes, considered from a capacity standpoint, it was not feasible 
to make a percentage or graphical comparison between the recom- 
mended formula, with varying coefficients and the other formulas 
mentioned on pages 5 to 8. Of these other formulas, some con- 
sider the influences of varying surfaces by means of coefficients, 
while others are inelastic and were offered for "clean pipes," regardless 
of materials. 
The point that must be kept continually in mind is that concrete 
pipes offer a greater range of interior surfaces, due to their initial 
construction, than pipes of any other material, considered by itself, 
or pipes of all other materials, considered together. These concrete 
surfaces are almost unbelievably different, aside from all fouling by 
growths, slimes, or erosion. 
In the following discussion classes 1, 2, 3, and 4 will be considered 
as was described on page 8, in connection with the new formula, the 
latter being considered as the base from which a comparison is made. 
