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" Sch-40 Steel Pipe
VEL
LOSS
HEAD
LOSS
PSI
2 1.20 1.91 .83
4 2.40 6.90 2.99
6 3.61 14.62 6.33
8 4.81 24.90 10.78
10 6.01 37.65 16.30
12 7.21 52.77 22.85
15 9.01 79.77 34.54
18 10.82 111.81 48.41
20 12.02 135.91 58.85
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 = 100 for water at 60 degrees F.
           (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