Page 227 - Water Engineering Hydraulics, Distribution and Treatment

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Problems/Questions
PROBLEMS/QUESTIONS
ing data are given:
An elevated water reservoir (water level at 210 m) is to supply
6.1
a lower groundwater reservoir (water level at 138 m). The reservoirs
are connected by 800 m of 400 mm ductile cast pipe (C = 100) and
d (mm)
Pipe
L (m)
1200 m of 300 mm ductile cast-iron pipe (C = 100) in series.
(a) What will be the discharge delivered from the upper reservoir
1,200
AB
300
to the lower one?
300
BD
300
200
AC
300
(b) If the water demand increases by 50% in the future, determine
CD
1,200
200
the required size of pipe that has to be installed in parallel with
SA
10,000
d
the existing piping.
SA
The following data are given for the water supply network
6.2
shown in Fig. 6.20: 6.4 For the water supply network shown in Fig. 6.21, the follow-
Elevation 655 m
Pipe d (in.) L (ft)
AB 8 2,500 S
BC 8 500
AD 8 500
DC 12 2,500
A B
The elevation of point A is 100 ft and of point B is 90 ft. The
C value for all pipes is 100. Find the following:
C D
(a) The length of a single 18 in. pipe that can replace the water
60 L/s
network from A to C.
(b) The residual pressure at point C, given that the flow through the Figure 6.21 Water network for Problem 6.4.
network is 4,000 gpm and the pressure at point A is 40 psi.
Elevation of loop ABCD is 600 m and the value of C for all
In
A B pipes = 100.
Determine the needed diameter of main SA so that the residual
pressure at any point in the network ABCD does not drop below
250 kPa.
6.5 Potable water is supplied to a city via an 800 mm transmission
line at a flow rate of 550 L/s (see Fig. 6.22). A pressure gauge located
500 m upstream from point A registers 6.5 bars at normal operation.
D C Out The following data are given:
Figure 6.20 Water network for Problems 6.2 and 6.3.
6.3 The following data are given for the water supply network Pipe d (mm) L (m)
shown in Fig. 6.20:
PA 800 500
AmnB 500 1,500
Pipe d (mm) L (m) AxyB 300 200
BC 800 —
AB 200 800
BC 200 200
AD 200 200
DC 300 800
All pipes are made of the same material with a Hazen–Williams
coefficient C = 100. The elevations of points P, A, and B are 650,
The elevation of point A is 600 m and of point B is 590 m. The 660, and 635 m, respectively.
C value for all pipes is 100. Find the following: (a) Determine the length of an equivalent 500 mm single pipe
(a) The length of a single 400 mm pipe that can replace the water between points A and B.
network from A to C. (b) Determine the actual flows in the two branches AmnB and
(b) The residual pressure at point C, given that the flow through the AxyB.
network is 250 L/s and the pressure at A is 300 kPa. (c) Find the residual pressures at both points A and B.