Determining flow rates – Xylem Wastewater (Technical Manual) User Manual
Page 14
PAGE 14
Wastewater
Goulds Water Technology, Bell & Gossett,
Red Jacket Water Products, CentriPro
An L-shaped measuring square can be used to estimate flow
capacity, using the chart below. As shown in illustration, place 4"
side of square so that it hangs down and touches the water. The
horizontal distance shown “A” is located in the first column of
the chart and you read across to the pipe diameter (ID) to find
the gallons per minute discharge rate.
Example: A is 8" from a 4" ID pipe
= a discharge rate of 166 GPM.
FULL PIPE FLOW – CALCULATION OF DISCHARGE RATE USING HORIZONTAL OPEN DISCHARGE FORMULA
Flow (GPM) = A x D x 1.093 x F
A = Area of pipe in square inches
D = Horizontal distance in inches
F = Effective area factor from chart
Area of pipe equals inside Dia.
2
x 0.7854
Example: Pipe inside diameter = 10 in.
D = 20 in.
F = 2½ in.
A = 10 x 10 x 0.7854 = 78.54 square in.
R % =
F
=
2½
= 25 %
D 10
F = 0.805
Flow = 78.54 x 20 x 1.039 x 0.805 = 1314 GPM
PIPE NOT RUNNING FULL – CALCULATION OF DISCHARGE RATE USING AREA FACTOR METHOD
Flow From Horizontal Pipe (Not Full)
Ratio
Eff. Area
Ratio
Eff. Area
F/D = R % Factor F F/D = R % Factor F
5 0.981 55 0.436
10 0.948 60 0.373
15 0.905 65 0.312
20 0.858 70 0.253
25 0.805 75 0.195
30 0.747 80 0.142
35 0.688 85 0.095
40 0.627 90 0.052
45 0.564 95 0.019
50 0.500 100 0.000
DISCHARGE RATE IN GALLONS PER MINUTE/NOMINAL PIPE SIZE (ID)
A
4"
F
D
12"
Determining Flow Rates
Horizontal
Pipe Diameter
Dist. (A)
1" 1¼"
1½" 2" 2½" 3" 4" 5" 6" 8" 10" 12"
Inches
4 5.7 9.8 13.3 22.0 31.3 48.5 83.5
5 7.1 12.2 16.6 27.5 39.0 61.0 104 163
6 8.5 14.7 20.0 33.0 47.0 73.0 125 195 285
7 10.0 17.1 23.2 38.5 55.0 85.0 146 228 334 380
8 11.3 19.6 26.5 44.0 62.5 97.5 166 260 380 665 1060
9 12.8 22.0 29.8 49.5 70.0 110 187 293 430 750 1190 1660
10 14.2 24.5 33.2 55.5 78.2 122 208 326 476 830 1330 1850
11 15.6 27.0 36.5 60.5 86.0 134 229 360 525 915 1460 2100
12 17.0 29.0 40.0 66.0 94.0 146 250 390 570 1000 1600 2220
13 18.5 31.5 43.0 71.5 102 158 270 425 620 1080 1730 2400
14 20.0 34.0 46.5 77.0 109 170 292 456 670 1160 1860 2590
15 21.3 36.3 50.0 82.5 117 183 312 490 710 1250 2000 2780
16 22.7 39.0 53.0 88.0 125 196 334 520 760 1330 2120 2960
17 41.5 56.5 93.0 133 207 355 550 810 1410 2260 3140
18
60.0 99.0 144 220 375 590 860 1500 2390 3330
19
110 148 232 395 620 910 1580 2520 3500
20
156 244 415 650 950 1660 2660 3700
21
256 435 685 1000 1750 2800
22
460 720 1050 1830 2920
23
750 1100 1910 3060
24
1140
2000
3200