Law Supply, Inc.
Web Page - Friction Loss Chart
Velocity in Ft./SEC.  Fiction Head Loss in feet of water per 100ft. of pipe
Gals. Per Min.
3" PVC Sch-40
VEL
LOSS
HEAD
LOSS
PSI
15 0.65 0.06 0.03
18 0.78 0.09 0.04
20 0.87 0.11 0.05
25 1.08 0.16 0.07
30 1.30 0.23 0.10
35 1.52 0.30 0.13
40 1.73 0.39 0.17
45 1.95 0.48 0.21
50 2.17 0.58 0.25
55 2.38 0.70 0.30
60 2.60 0.82 0.36
65 2.82 0.95 0.41
70 3.03 1.09 0.47
75 3.25 1.24 0.54
80 3.47 1.39 0.60
85 3.68 1.56 0.68
90 3.90 1.73 0.75
95 4.12 1.92 0.83
100 4.33 2.11 0.91
110 4.77 2.51 1.09
120 5.20 2.92 1.26
130 5.63 3.43 1.49
140 6.07 3.93 1.70
150 6.50 4.47 1.94
160 6.94 5.03 2.18
170 7.37 5.63 2.44
180 7.80 6.26 2.71
190 8.24 6.92 3.00
200 8.67 7.61 3.30
220 9.54 9.08 3.93
240 10.40 10.66 4.62
260 11.27 12.37 5.36
280 12.14 14.19 6.14
300 13.00 16.12 6.98
320 13.87 18.17 7.87
340 14.74 20.33 8.80
360 15.60 22.60 9.79
380 16.47 24.98 10.82
400 17.34 27.46 11.89
450 19.51 34.16 14.79
500 21.67 41.52 17.98
550 23.84 49.53 21.45
600 26.01 58.20 25.20
650 28.17 67.50 29.23
LBS. per square in. = Head in ft. x .433
Head in ft. = lbs. per sq. in. x 2.31'
The velocity of two (2) feet per second is generally accepted as the velocity ot carry solids.
Data shown is calculated form Williams and Hazen formula:
   H = 1043.94 X ((Q^1.852) / ((C^1.852 X D^4.8655)))
USING: C = 150 for water at 60 degrees F. and plastic pipe.
           (coefficient for roughness of the interior pipe surface)
       H = head loss in FT.
       V = fluid velocity in FT/SEC.
       D = inside diameter of the pipe in INCHES.
       Q = flow rate GPM

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Last updated 05/19/2003