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7 question and i attached ch7 doct Also i attached ch7 pdf
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Industrial Ventilation
(Chapter 7)
1. The circumference of a round duct is about 37.5 inches. The average velocity
pressure (VP) of air flowing in the duct is 0.30 inch w.g. at standard conditions
a) Duct diameter
b) Average Vduct
c) Air flowrate Q, and compare your Q with that on Chart 5 to determine the
difference.
2. The average air velocity pressure (VP) of an airstream in a duct is 0.90 inch w.g.
The temperature of the air is T = 75 ℉ and the duct is located 1,000 ft above sea
level. What is the actual average air velocity?
Hint: you need find B.P. online for df calculation.
3. Standard air (d=1) moves through a galvanized duct system at the velocity (Vaverage)
of 5,000 fpm and Dduct is 8 inches.
• List the three equations that you use to solve the problem.
• Please find the loss factors K from the Charts, and then estimate static pressure
loss for each component in each branch (a-f).
• Please calculate the friction loss for the entire duct system, La-f = 50’, galv duct
1
Component
a. Flanged hood (round)
b. Plain duct hood (round)
c. Elbow, 3-piece, R/D=1.5,
90°
d. Elbow, 5-piece, R/D=1.0,
90°
e. Elbow, 4-piece, R/D=2.0,
45°
f. Branch entry, 60° included
angle
Friction loss (FL), La-f = 50’,
galv duct
K or
Fh
Where can you find the K
value?
Chart 11A
Chart 11A
Chart 5
SP loss
(“w.g.)
FL =
4. Discuss how you can use blast gate method to balance the SP between branches.
You can give an example and/or use diagram.
5. A ventilation system has two branches: one branch requires to have SP of – 5.3”
w.g. and Q of 4.8 scfm, and the other needs -6.1 “w.g and 5.2 scfm. 1) Determine
the governing static pressure for a ventilation system; and 2) Determine the Qcorrect
and specify whether the Qcorrect you calculate is for governing or for non-governing
branch.
6. There are several limitations when using blast gate method. Please pick one
limitation of your interest, and discuss what method(s) YOU can use to solve the
potential problem.
2
7. A ventilation system with two branches: one branch requires to have SP of – 5” w.g.
and Q of 4.8 scfm. Determine the maximum range of SP for another branch that
allow you to determine the governing static pressure without a further design change
needed.
3

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