Page 188 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Grit Chambers 143

TABLE CD7.5
Dimensions and Capacities for Parshall Flumes
(a) Metric units
Free Flow
Throat Capacities Dimensions (m)
Width (m =s)
3
(m) A B C 2=3C D E F G H K X Y
0.025 0.00028 0.0006 0.17 0.093 0.365 0.242 0.356 0.076 0.204 0.152 0.029 0.019 0.008 0.013
0.051 0.00057 0.0113 0.21 0.135 0.414 0.029 0.406 0.114 0.253 0.204 0.043 0.022 0.016 0.025
0.076 0.00085 0.017 0.26 0.178 0.466 0.305 0.457 0.152 0.305 0.381 0.057 0.076 0.025 0.038
0.152 0.0014 0.0821 0.39 0.394 0.621 0.415 0.61 0.305 0.61 0.457 0.114 0.076 0.051 0.076
0.229 0.00283 0.1444 0.58 0.381 0.878 0.588 0.863 0.305 0.457 0.61 0.114 0.076 0.051 0.076
0.305 0.0113 0.4531 0.84 0.61 1.372 0.914 1.344 0.61 0.914 0.914 0.229 0.076 0.051 0.076
0.457 0.0142 0.6797 1.02 0.762 1.448 0.966 1.42 0.61 0.914 0.914 0.229 0.076 0.051 0.076
0.61 0.0198 0.9346 1.21 0.914 1.524 1.015 1.497 0.61 0.914 0.914 0.229 0.076 0.051 0.076
0.762 0.0227 1.1611 1.39 1.067 1.631 1.085 1.6 0.61 0.914 0.914 0.229 0.076 0.051 0.076
0.914 0.0283 1.416 1.68 1.219 1.676 1.119 1.646 0.61 0.914 0.914 0.229 0.076 0.051 0.076
1.219 0.0368 1.9258 1.94 1.524 1.829 1.219 1.792 0.61 0.914 0.914 0.229 0.076 0.051 0.076
1.524 0.0623 2.435 2.30 1.823 1.981 1.295 1.945 0.61 0.914 0.914 0.229 0.076 0.051 0.076
1.829 0.0736 2.945 2.67 2.134 2.134 1.423 2.091 0.61 0.914 0.914 0.229 0.076 0.051 0.076
2.134 0.116 3.427 3.03 2.438 2.286 1.524 2.24 0.61 0.914 0.914 0.229 0.076 0.051 0.076
2.438 0.130 3.965 3.40 2.743 2.438 1.60 2.39 0.61 0.914 0.914 0.229 0.076 0.051 0.076
3.048 0.170 5.664 4.76 3.658 4.349 1.83 4.27 0.914 1.829 1.219 0.343 0.152 0.305 0.229
(b) U.S. Customary units
Free Flow
Throat Capacities Dimensions (ft)
Width
3
(ft =s)
(ft) A B C 2=3C D E F G H K X Y
0.083 0.01 0.02 0.55 0.305 1.19 0.794 1.167 0.25 0.67 0.5 0.094 0.062 0.026 0.042
0.166 0.02 0.4 0.70 0.442 1.36 0.906 1.333 0.375 0.83 0.67 0.14 0.073 0.052 0.083
0.25 0.03 0.6 0.85 0.583 1.53 1.02 1.50 0.50 1.00 1.25 0.188 0.25 0.083 0.125
0.5 0.05 2.9 1.29 1.292 2.036 1.36 2.00 1.00 2.00 1.50 0.375 0.25 0.167 0.25
0.75 0.1 5.1 1.89 1.25 2.88 1.93 2.83 1.00 1.50 2.00 0.375 0.25 0.167 0.25
1 0.4 16 2.77 2.00 4.50 3.00 4.41 2.00 3.00 3.00 0.75 0.25 0.167 0.25
1.5 0.5 24 3.36 2.50 4.75 3.17 4.66 2.00 3.00 3.00 0.75 0.25 0.167 0.25
2 0.7 33 3.96 3.00 5.00 3.33 4.91 2.00 3.00 3.00 0.75 0.25 0.167 0.25
2.5 0.8 41 4.56 3.50 5.35 3.56 5.25 2.00 3.00 3.00 0.75 0.25 0.167 0.25
3 1.00 50 5.16 4.00 5.50 3.67 5.40 2.00 3.00 3.00 0.75 0.25 0.167 0.25
4 1.3 68 6.35 5.00 6.00 4.00 5.88 2.00 3.00 3.00 0.75 0.25 0.167 0.25
5 2.2 86 7.55 6.00 6.50 4.25 6.38 2.00 3.00 3.00 0.75 0.25 0.167 0.25
6 2.6 104 8.75 7.00 7.00 4.67 6.86 2.00 3.00 3.00 0.75 0.25 0.167 0.25
7 4.1 121 9.95 8.00 7.50 5.00 7.35 2.00 3.00 3.00 0.75 0.25 0.167 0.25
8 4.6 140 11.1 9.00 8.00 5.25 7.84 2.00 3.00 3.00 0.75 0.25 0.167 0.25
10 6.0 200 15.6 12.0 14.27 6.00 14.0 3.00 6.00 4.00 1.125 0.50 1.00 0.75

Source: Adapted from Skogerboe, G.V. et al., Parshall Flumes, Report WG31-3, OWRR Project No. B-006-Utah, Utah Water Research Laboratory, Utah
State University, Logan, UT, March, 1967.

Example 7.4 Parshall Flume Selection Required
and Rectangular Grit Chamber Sizing Select a Parshall flume and size a compatible grit
chamber.
Statement Solution
A maximum expected flow through a treatment plant is From Table 7.3, a 0.61 m (24 in.) flume has a capacity of
3
3
3
Q(max) ¼ 0.765 m =s (27.0 ft =s). Let Q(min) ¼ 0.425 m =s 0.934 m =s (33.0 ft =s) and gives coefficients C ¼ 1.43 SI
3
3
3
(15.0 ft =s). (8 US) and n ¼ 1.55. Determining H a from Equation 7.6