Chapter 19
302
CHAPTER NINETEEN
FLOW OF AIR IN DUCTS
FLOW OF AIR DUCTS
303
19.
8
3
10
in
d
u
c
t
:
19.9 42 60 in duct:
19.10 250 500 mm duct:
19.11 75 250 mm duct:
19.12 Q = 1500 cfm; max
h = 0.10 in H2O per 100 ft De = 16.2 in
Energy losses in ducts with fittings
19.14 Q = 650 cfm; D = 12 in round;
= 830 ft/min (Fig. 19.2)
19.15 C = 0.33 5-pc elbow; HL = CH
= 0.33(0.0429) = 0.0142 in H2O
FLOW OF AIR DUCTS
305
19.25 12 20 rect 16.8 in Circ. Eq.; use Q = 1500 cfm;
= 980 ft/min
19.26 Q = 0.80 m3/s
For square duct:
1e
D =
5 / 8
1/ 4
1.3 (800)(800)
(800 800) = 875 mm Circ. Eq.
1L
2L
H= 17 Pa (Table 19.3) louvers