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6.6 Office Studies of Pipe Networks 215

Discharge coefficient C of given pipe
15 20 30 40 50 60 70 80 100 150 200 300 400
10 10
9 9
8 8
7 7
6 6

5 5 4
C and d factors 3 d-factor, multiply by 10 4 C-factor, read directly C-factor, multiply by 10 1 3 C and d factors
4

2 10 3 10 2 10 1 d-factor, read directly 10 3 10 4 2

1.5 10 1.5
10 2

1 1
0.15 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.91.0 1.5 2 3 4 5 6 7 8 9 10
Diameter ratio d e /d of equivalent to given pipe
Figure 6.15 Length, Diameter, and Coefficient (L e , d e , and C e 100) of Pipe Hydraulically Equivalent to an Existing Pipe of
Given L, d, and C

e
where L e is the length of a pipe of diameter d ; discharge coefficient C 100; and L, d, and C
are the corresponding properties of the existing pipe. The desired values for L can be found
readily from a logarithmic plot of L L against d d at given values of C, as shown in Fig. 6.15.
e
e
The readers are referred to Chapters 5 and 13 for all Hazen-Willliams equations using
the SI units.

EXAMPLE 6.6 DETERMINATION OF EQUIVALENT PIPE
Find the length of a 24-in. (600-mm) pipe with C 100 that is equivalent to a 12-in. (300-mm)
pipe with C 130 and L 2,000 ft (610 m).

Solution:
At C 130 read the C-factor 6.2 10 –1
At d e d 2.0, read the d-factor 2.9 10
–1
Hence L e L (6.2 10 ) (2.9 10) 18
L e 2,000 18 36,000 ft (10,973 m)

6.6.4 Computer Programming
High-speed computers can be programmed to solve network problems in a number of
different ways. Convergence formulas need not be introduced as such. Instead, the com-
puter can be assigned the task of adjusting the water table or pressure at each junction