Question 1

A fine dining restaurant wants quiet air flow in its dining room, so a duct flow of 250 ft/min is desired. The size of the room requires the duct to have a flow of 1,400 CFM to properly control the room's environment. What is the cross-sectional area of the duct to the nearer tenth square foot?

Accepted Answer

5.6 sq ft

Question 2

The flow of air in a duct should stay less than 490 ft/min to keep the air flow from being too noisy. The dining room of a house is to have a flow of 150 cu ft/min to have proper air exchange. What should be the smallest duct area going to this room? Round answer to the nearer thousandths sq ft.

Accepted Answer

0.306 sq ft

Question 3

What would be the smallest bedroom that should be supplied air by a 10-inch by 12-inch duct with a flow of 50 ft/min for 6 changes each hour? Round the answer to the nearer hundredth cubic foot if needed.

Accepted Answer

416.67 cu ft

Question 4

The air flow in a duct in a house should have a speed faster than 50 ft/ min so that it does not lose heat in the winter or gain heat in the summer before reaching the room. The dining room of a house is to have a flow of 150 cu ft/min to have proper air exchange. What should be the largest duct area going to this room?

Accepted Answer

The answer of The air flow in a duct in...

Question 5

The air flow rate in a duct can be found by multiplying the area of the duct times the air speed in the duct.

Accepted Answer

This statement is true. The formula for calculating air flow rate in a duct is Q = A x V, where Q is the flow rate in cubic feet per minute (CFM), A is the cross-sectional area of the duct in square feet, and V is the air velocity in feet per minute (FPM).

Question 6

A room in a house is 14 feet 6 inch by 12 feet 6 inches. It has 8-ft ceilings. What must the air flow into the room be in cubic feet per minute to have 6 air changes per hour? Round the answer to the nearer hundredth CFM if needed.

Accepted Answer

The answer of A room in a house is 14...

Question 7

A 3,250 sq ft house with 8 foot ceilings has 3 return ducts. What size must the ducts be to handle 7 exchanges per hour with a flow of 350 ft/min? Round the answer to the nearer hundredth square foot.

Accepted Answer

The answer of A 3,250 sq ft house with 8...

Question 8

A fan produces a flow of 3,400 CFM. What area duct will give an air speed of 350 ft/min in the duct? Round answer to the nearer hundredth square foot.

Accepted Answer

The answer of A fan produces a flow of 3,400...

Question 9

The units of air flow rate are given in square feet per minute.

Accepted Answer

The units of air flow rate are typically given in cubic feet per minute (CFM) or liters per second (L/s).

Question 10

A distribution duct has an area of 2.1 sq ft and an air speed of 340 ft/ min. A side duct of 1.0 sq ft splits off. The main duct reduces in size to 1.4 sq ft. What is the air flow in the main duct after the split?

Accepted Answer

The answer of A distribution duct has an area of...

Quiz 33: Air Flow Calculations