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.
3/4" PVC Sch-40
VEL
LOSS
HEAD
LOSS
PSI
2 1.20 0.90 0.39
4 2.40 3.26 1.41
6 3.61 6.90 2.99
8 4.81 11.75 5.09
10 6.01 17.77 7.69
12 7.21 24.90 10.78
15 9.01 37.65 16.30
18 10.82 52.77 22.85
20 12.02 64.14 27.77
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