Page 209 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

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5.2 Fluid Transport 171

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The nomogram (C 100) of Fig. 5.6 for D 400 mm and Q 0.210 m /s will give
s 11%
h f sL 11‰ 3,300 m 36 m
P A 580 30 600 36
P A 86 m or 8.6 bars is the actual pressure at point A

EXAMPLE 5.7 APPLICATIONS OF HAZEN-WILLIAM FORMULA
Determine the expected velocity, full flow and headloss for a 24-in. (609.6 mm) circular conduit
with a Hazen-William coefficient C 100, a length L 1,000 ft (304.8 m), and a hydraulic gra-
dient s 2.25%.

Solution 1 (U.S. Customary System):
1. According to the nomogram shown in Fig. 5.6,
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v 3.3 ft/s and Q 10. ft /s
s 0.0025 h f /L h f /1,000 ft
h f 1,000 ft 0.0025 2.5 ft
2. Using Eq. 5.34 and Eq. 5.36,
v 0.115 cd 0.63 0.54 0.115 100(24) 0.63 (0.0025) 0.54 3.3 ft/s
s
s
v 0.55 CD 0.63 0.54 0.55 100(24/12) 0.63 (0.0025) 0.54 3.3 ft/s
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s
Q ft /s 0.432 CD 2.63 0.54 0.432 100(24/12) 2.63 (0.0025) 0.54 10.5 ft /s
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h f 1,000 ft 0.0025 2.5 ft
Solution 2 (SI System):
1. According to the nomogram shown in Fig. 5.6,
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v 1 m/s and Q 0.28 m /s
h f 304.8 m 0.0025 0.762 m
2. Using Eq. 5.34 and Eq. 5.36,
s
v 0.3545 CD 0.63 0.54 0.3545 100(0.6096) 0.63 (0.0025) 0.54 1 m/s
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s
Q m /s 0.278 CD 2.63 0.54 0.278 100(0.6096) 2.63 (0.0025) 0.54 0.298 m /s
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h f 304.8 m 0.0025 0.762 m

5.2.3 Form Resistance
Pipeline transitions and appurtenances add form resistance to surface resistance. Head
losses are stepped up by changes in cross-sectional geometry and changing directions
of flow. Expansion and contraction exemplify geometric change; elbows and branches,
directional change. Valves and meters as well as other appurtenances may create both
geometrical and directional change. With rare exceptions, head losses are expressed
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either in terms of velocity heads, such as Kv >2g, or as equivalent lengths of straight pipe,