Flowrates and Slope of Horizontal Drainage Piping
1
THERMOPLASTIC ENGINEERING FOR SERVICE, PLEASE CALL 1-800-877-HIPCO Q = A x x R 2/3 x S 1/2 (7.48x60) SLOPE INCHES PER FOOT S FOOT PER FOOT S 1/2 1/8 1/4 1/2 0.0104 0.0208 0.0416 0.102 0.144 0.204 PIPE SIZE n 1-1/2” 2” through 3” 4” 5” and 6” 8” and larger 0.012 0.013 0.014 0.015 0.016 Table 39 VALUES OF S AND S 1/2 . Table 40 VALUES OF n. DISCHARGE GPM VELOCITY FPS ACTUAL INSIDE DIAMETER OF PIPE INCHES DISCHARGE GPM DISCHARGE GPM DISCHARGE GPM VELOCITY FPS VELOCITY FPS VELOCITY FPS FLOWING HALF FULL DISCHARGE RATE AND VELOCITY 1/16 IN./FT. SLOPE 1/8 IN./FT. SLOPE 1/4 IN./FT. SLOPE 1/2 IN./FT. SLOPE 1-1/4 1-3/8 1-1/2 1-5/8 2 2-1/2 3 4 5 6 8 10 12 - - - - - - - 26.70 48.3 78.5 170. 308. 500. - - - - - - - 1.36 1.58 1.78 2.17 2.52 2.83 - - - - - 10.8 17.6 37.8 68.3 111. 240. 436. 707. - - - - - 1.41 1.59 1.93 2.23 2.52 3.07 3.56 4.01 - 3.13 3.91 4.81 8.42 15.3 24.8 53.4 96.6 157. 340. 616. 999. - 1.34 1.42 1.50 1.72 1.99 2.25 2.73 3.16 3.57 4.34 5.04 5.67 3.40 4.44 5.53 6.80 11.9 21.6 35.1 75.5 137. 222. 480. 872. 1413. 1.78 1.90 2.01 2.12 2.43 2.82 3.19 3.86 4.47 5.04 6.13 7.12 8.02 Table 41 APPROXIMATE DISCHARGE RATES AND VELOCITIES IN SLOPING DRAINS SLOPE OF HORIZONTAL DRAINAGE PIPING R = FEET D 4 PIPE SIZE (IN.) R 2/3 A - CROSS-SECTIONAL AREA FOR FULL FLOW SQ. FT. A - CROSS-SECTIONAL AREA FOR HALF FULL FLOW SQ. FT. 1-1/2 2 2-1/2 3 4 5 6 8 10 12 14 0.0335 0.0417 0.0521 0.0625 0.0833 0.1040 0.1250 0.1670 0.2080 0.2500 0.3125 0.1040 0.1200 0.1396 0.1570 0.1910 0.2210 0.2500 0.3030 0.3510 0.3970 0.4610 0.01412 0.02180 0.03408 0.04910 0.08730 0.13640 0.19640 0.34920 0.54540 0.78540 1.22700 0.00706 0.01090 0.01704 0.02455 0.04365 0.06820 0.09820 0.17460 0.27270 0.39270 0.61350 Table 38 Horizontal drains are designated to flow at half full capacity under uniform flow conditions so as to prevent the generation of positive pressure fluctuations. A minimum of 1/4” per foot should be provided for 3” pipe and smaller, 1/8” per foot for 4” through 6”, and 1/16” per foot for 8” and larger. These minimum slopes are required to maintain a velocity of flow greater than 2 feet per second for scouring action. Table 41 gives the approximate velocities and discharge rated for given slopes and diameters of horizontal drains based on modified Manning Formula for 1/2 full pipe and n = 0.015. The valves for R, R 2/3, A, S, S 1/2 and n are from Tables 38, 39 & 40. 1.486 n Where: Q = Flow in GPM R = Hydraulic radius of pipe A = Cross sectional area, sq. ft. S = Hydraulic gradient n = Manning coefficient
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Flowrates and slope of Horizontal Drains
Transcript of Flowrates and Slope of Horizontal Drainage Piping
TH
ER
MO
PLA
ST
IC E
NG
INE
ER
ING
FOR SERVICE, PLEASE CALL 1-800-877-HIPCO
Q = A x x R 2/3 x S 1/2 (7.48x60)
SLOPEINCHES
PER FOOTS
FOOT PER FOOT S 1/2
1/8
1/4
1/2
0.0104
0.0208
0.0416
0.102
0.144
0.204
PIPE SIZE n
1-1/2”
2” through 3”
4”
5” and 6”
8” and larger
0.012
0.013
0.014
0.015
0.016
Table 39 VALUES OF S AND S 1/2. Table 40 VALUES OF n.
DISCHARGEGPM
VELOCITYFPS
ACTUAL INSIDEDIAMETER
OF PIPEINCHES
DISCHARGEGPM
DISCHARGEGPM
DISCHARGEGPM
VELOCITYFPS
VELOCITYFPS
VELOCITYFPS
FLOWING HALF FULL DISCHARGE RATE AND VELOCITY
1/16 IN./FT.SLOPE
1/8 IN./FT.SLOPE
1/4 IN./FT.SLOPE
1/2 IN./FT.SLOPE
1-1/4
1-3/8
1-1/2
1-5/8
2
2-1/2
3
4
5
6
8
10
12
-
-
-
-
-
-
-
26.70
48.3
78.5
170.
308.
500.
-
-
-
-
-
-
-
1.36
1.58
1.78
2.17
2.52
2.83
-
-
-
-
-
10.8
17.6
37.8
68.3
111.
240.
436.
707.
-
-
-
-
-
1.41
1.59
1.93
2.23
2.52
3.07
3.56
4.01
-
3.13
3.91
4.81
8.42
15.3
24.8
53.4
96.6
157.
340.
616.
999.
-
1.34
1.42
1.50
1.72
1.99
2.25
2.73
3.16
3.57
4.34
5.04
5.67
3.40
4.44
5.53
6.80
11.9
21.6
35.1
75.5
137.
222.
480.
872.
1413.
1.78
1.90
2.01
2.12
2.43
2.82
3.19
3.86
4.47
5.04
6.13
7.12
8.02
Table 41 APPROXIMATE DISCHARGE RATES AND VELOCITIES IN SLOPING DRAINS
SLOPE OF HORIZONTAL DRAINAGE PIPING
R =
FEET
D4
PIPESIZE(IN.) R 2/3
A - CROSS-SECTIONALAREA FOR FULL FLOW
SQ. FT.
A - CROSS-SECTIONALAREA FOR HALF FULL FLOW
SQ. FT.
1-1/2
2
2-1/2
3
4
5
6
8
10
12
14
0.0335
0.0417
0.0521
0.0625
0.0833
0.1040
0.1250
0.1670
0.2080
0.2500
0.3125
0.1040
0.1200
0.1396
0.1570
0.1910
0.2210
0.2500
0.3030
0.3510
0.3970
0.4610
0.01412
0.02180
0.03408
0.04910
0.08730
0.13640
0.19640
0.34920
0.54540
0.78540
1.22700
0.00706
0.01090
0.01704
0.02455
0.04365
0.06820
0.09820
0.17460
0.27270
0.39270
0.61350
Table 38
Horizontal drains are designated to flow at half full capacity under uniform flow conditions so as to prevent the generation ofpositive pressure fluctuations. A minimum of 1/4” per foot should be provided for 3” pipe and smaller, 1/8” per foot for 4”through 6”, and 1/16” per foot for 8” and larger. These minimum slopes are required to maintain a velocity of flow greaterthan 2 feet per second for scouring action. Table 41 gives the approximate velocities and discharge rated for given slopesand diameters of horizontal drains based on modified Manning Formula for 1/2 full pipe and n = 0.015. The valves for R, R2/3, A, S, S 1/2 and n are from Tables 38, 39 & 40.
1.486n
Where: Q = Flow in GPM R = Hydraulic radius of pipeA = Cross sectional area, sq. ft. S = Hydraulic gradientn = Manning coefficient
Tom
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