Skip to main content

Duct sizing

The following ducts sizes (inches) are given as rough equivalents to deliver the same CFM. Based on shape, which offers the least resistance to air movement and the least friction?
A. 5x12, B. 6x10, C. 7x8, D. 9 dia.




Answer = D. 9 in. diameter round duct. Although yielding slightly more cross-sectional area, this duct has the least perimeter and based on shape is the most efficient (least resistance and least friction).  ⭕

For more exam resources see the PPD-PPD page

Comments

Post a Comment

Try These Too!

Structural forces

Choose a term that best identifies the type of force shown in this diagram - A. collinear B. concurrent C. nonconcurrent D. noncoplanar
Post a Comment
See the answer »

Roof pitch

Which one of the following slopes in this illustration corresponds with an 8:12 pitch roof? A. 45° B. 36.87° C. 33.69° D. 26.57°
Post a Comment
See the answer »

Bolted connections

What is the minimum spacing of bolts specified by AISC? and preferred spacing? A. 1 1/4 times the diameter of the bolt; 2 times preferred B. 1 3/4 times the diameter of the bolt; 2 1/4 times preferred C. 2 1/3 times the diameter of the bolt; 2 2/3 times preferred D. 2 2/3 times the diameter of the bolt; 3 times preferred E. 3 times the diameter of the bolt; 3.25 times preferred
Post a Comment
See the answer »