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!

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 »

Brick bonds

What distinguishes the English Bond pattern from the Dutch Bond pattern in this image? Answer In the English Bond, stretchers are aligned; In the Dutch (cross), stretchers move by a half each course (not aligned). ARE 4.0 exam prep: BDCS
Post a Comment
See the answer »

Collector walks

Walks next to parking areas where vehicles are able to overhang the walk should be a minimum width. What is this minimum in feet? A. 3 feet B. 4 feet C. 5 feet D. 6 feet Answer These walks should be 6 ft (D.) minimum in width. ARE 4.0 exam prep: SPD
Post a Comment
See the answer »