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.
1-1/4" PVC Sch-40
VEL
LOSS
HEAD
LOSS
PSI
2 0.43 0.07 0.03
4 0.86 0.26 0.11
6 1.29 0.56 0.24
8 1.71 0.96 0.42
10 2.14 1.45 0.63
12 2.57 2.03 0.88
15 3.21 3.06 1.32
18 3.86 4.29 1.86
20 4.28 5.22 2.26
25 5.36 7.89 3.42
30 6.43 11.06 4.79
35 7.50 14.71 6.37
40 8.57 18.84 8.16
45 9.64 23.43 10.15
50 10.71 28.48 12.33
55 11.78 33.97 14.71
60 12.85 39.91 17.28
65 13.93 46.29 20.04
70 15.00 53.10 22.99
75 16.07 60.34 26.13
80 17.14 68.00 29.44
85 18.21 76.08 32.94
90 19.28 84.57 36.62
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