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!

Townships double post!

How many sections are contained within a township? Answer 36 (each is 1 mile square) What are the dimensions of 1/2 of a township? H & W Answer 18 miles square (3x6 sections) ARE 4.0 exam prep: SPD
4 comments
See the answer »

Parking units

What are the car stall dimensions for a compact car? Answer A compact car stall size can be set by each municipality and therefore varies. Generally it is 7ft 6in wide by 15ft 0in long. However, in Fresno CA it's 8 1/2ft x 16ft and according to an Iowa urban design manual, it's 7ft 6in by 16ft. ARE 4.0 exam prep: SPD
4 comments
See the answer »

Building Efficiency

Convert the usable area of classrooms planned with medium efficiency level of new construction to the gross building area given the following model factors: Net Assignable Square Feet: 10,000, Space Factor: 1.5, Building Efficiency Ratio: 67%
6 comments
See the answer »