Unformatted text preview: P11.74 The 32in pump in Fig. 117:: is used at 1170 r/min in
“(a system whose head curve is H, (ft) = 100 + 1.5Q2,
 with Q in thousands of gallons of water per minute. Find
the discharge and brake horsepower required for (a) one
pump, (b) two pumps in parallel, and (c) two pumps in series. Which conﬁguration is best?
P11.75 Two 35in pumps from Fig. 11.7b are installed in par
1 allel for the system of Fig. P11.75. Neglect minor losses.
[—7 7 For water at 20°C, estimate the ﬂow rate and power
required if (a) both pumps are running and (b) one pump is shut off and isolated. 2,. 1 statute mile
of cast iron pipe.
24—in diameter . 21:2(Xlﬂ Two pumps
P11.75 P11.76 Two 32—in pumps from Fig. 11.70 are combined in par
allel to deliver water at 60°F through 1500 ft of hori
zontal pipe. If f 2 0.025, what pipe diameter will ensure
a ﬂow rate of 35.000 gal/min for n = 1170 r/min? Cll.1 The net head of a little aquarium pump is . ‘ ~ . given by the
manufacturer as a tunction of volume ﬂow rate as listed below:
—._.__.__
Q. 1113/5 H. an30
M
0 1.10
1.0 136 1.00
2.0 15—6 0.80
3.0 136 0.60
4.0 E~6 0.35
5.0 E»() 0.0
W What is the maximum achievable ﬂow rate if you use this
pump to move water from the lower reservoir to the
upper reservorr as shown in Fig. Cl 1 . 1? Note: The tubinu
lS smooth with an inner diameter of 5.0 mm and a total
length of 29.8 m. The water is at room temperature and
pressure. Minor losses in the system can be neglected. Cl.1.1 ...
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 Spring '08
 Terry

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