126 ENVIRONMENTAL ENGINEEIUNG
- Assume any arbitrary head loss, say 10 ft.
- Calculate head loss in feet per 1000 ft for pipes 1 and 2.
Pipe 1: (10/1300) x (1000) = 7.7 ft/lOOOft
Pipe 2: (10/1400) x (1000) = 7.1 ft/1000 ft.
- Use Fig. 6-11 to find flow in gallons per minute (gpm).
Pipe 1: D = 8 in., s = 0.0077, Q = 495 gpm
Pipe 2: D = 6 in., s = 0.0071, Q = 220 gpm
Total Q through both pipes = 715 gpm.
- Using Fig. 6-1 1 with s = 0.010 and Q = 715 gpm, equivalent pipe size is found
to be 8.8 in. in diameter.
Table 6-3. Values of C for the Hazen-Williams Equation
Type of pipe C
Asbestos cement
Brass
Brick sewer
Cast iron
New, unlined
Old, unlined
Cement-lined
Bitumastic enamel-lined
Tar-coated
Concrete or concretelined
Steel forms
Wooden forms
Centsifugally spun
Copper
Fire hose (rubber-lined)
Galvanized iron
Glass
Lead
Masonry conduit
Plastic
Steel
Coal-tar enamel-lined
New, unlined
Riveted
Tin
Vitrified
Wood stove
140
130-140
100
130
40-120
130-150
140-150
1 15-1 35
140
120
135
130-140
135
120
140
130-140
120-140
140-150
145-150
140-150
110
130
100-140
120
