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294 Chapter 8 Pumping, Storage, and Dual Water Systems
(500-mm) pipe (C 100), which is 30,000 ft (9,144 m) long. How large a storage tank would be required to equalize supply
The pumping station has two pumps, each of which possesses and demand for each of the following conditions?
the following characteristics:
(a) Water is obtained from a nearby city at a uniform
rate from 8 a.m. to 4 p.m.
Flow (gpm) 15,852 31,704 47,556 63,408 79,260 95,112 110,964
(b) Water is obtained from the same city at a uniform
Head (ft) 951 886 804 689 558 410 213 rate over the 24-hr period.
8.16 For the water supply of a small town with a daily water re-
3
quirement of 0.594 MG (2,250 m ), the construction of a water
Flow (L/s) 1,000 2,000 3,000 4,000 5,000 6,000 7,000
reservoir has been proposed. The pattern of drawoff is as follows:
Head (m) 290 270 245 210 170 125 65
Shutoff head 300 ft (91.44 m) Period % of Daily Demand
7 a.m. to 8 a.m. 30
What will be the discharge of the two pumps when operat- 8 a.m. to 5 p.m. 35
ing in series? Also what will be the total head against which the 5 p.m. to 6:30 p.m. 30
pumps are actually operating? 8:30 p.m. to 7 a.m. 5
8.14 An industrial complex utilizes water at a uniform rate of
5,400 gpm (20,439 L/min) during its working hours from 8 a.m. Water is to be supplied to the reservoir at a constant rate for a
to noon and from 4 p.m. to 8 p.m. This water demand is with- period of 8 hours, 8 a.m. to 4 p.m. Determine the storage capacity
drawn from an elevated water tank located at an elevation of 40 of the reservoir needed to balance supply and demand. No storage
ft (12.19 m) above ground level. for fire is required. If pumping is to be done at a constant rate over
Water is pumped at a uniform rate continuously through- the 24 hours, what will then be the required reservoir size?
out the day to the tank using two pumps connected in series 8.17 An industrial plant requires 5,000 gpm (316 L/s) of
from a well whose water level is 460 ft (104.21 m) below water during its on-shift hours from 6 a.m. to 10 p.m. How large
ground level. The water pipe from the well to the tank is 3,000 ft (in gallons or liters) a storage tank would be required to equal-
(914.4 m) long when C 100. ize the pumping rate for each of the following conditions:
Each pump has the following characteristics:
(a) Water is obtained from a well at a uniform rate
over the 24-h period.
Flow (gpm) 0 1,000 2,000 3,000 4,000
(b) Water is obtained from a well during the period from
Head (ft) 350 325 275 175 50
10 p.m. to 6 a.m., which is the off-peak period of elec-
tricity consumption.
8.18 A factory requires 793 gpm (50 L/s) of water during its
Flow (L/s) 0 63 126 189 252
working hours from 8 a.m. to 4 p.m. How large a storage reser-
Head (m) 106.68 99.06 83.82 53.34 15.24
voir would be required to equalize supply and demand for each
of the following water supply conditions?
(a) Calculate the water tank volume required to equalize
supply and demand. (a) Water is supplied from a well at a uniform rate over
the 24-h period.
(b) Determine the size of the pipe delivering water from
the well to the water tank. (b) Water is supplied at a uniform rate from the city net-
work during the off-peak period from 4 p.m. to 8 a.m.
8.15 A summer resort complex consumes water at the follow-
ing uniform rates during the indicated periods: 8.19 A residential neighborhood, population 20,000, is sup-
plied with water from an elevated reservoir. The daily water
Period Consumption Rate (gpm) consumption is as follows:
Midnight to 8 a.m. 5.4 Period % of Daily Demand
8 a.m. to 4 p.m. 11.4
4 p.m. to midnight 8.2 Midnight to 3 a.m. 5
3 a.m. to 6 a.m. 7
6 a.m. to 9 a.m. 13
3
Period Consumption Rate (m /h) 9 a.m. to noon 20
Noon to 3 p.m. 20
Midnight to 8 a.m. 20 3 p.m. to 6 p.m. 15
8 a.m. to 4 p.m. 50 6 p.m. to 9 p.m. 10
4 p.m. to midnight 30 9 p.m. to midnight 10