HVAC Sheet Metal and Fabrication 2

Question 1

What is the standard gauge thickness for residential HVAC supply ductwork in low-pressure systems?

Accepted Answer

26 gauge

Answer

26 gauge galvanized steel is the standard minimum thickness for residential low-pressure supply ductwork per SMACNA guidelines.

Question 2

Which type of joint is used to connect two sections of rectangular duct end-to-end in the field?

Accepted Answer

S-slip and drive cleat

Answer

The S-slip and drive cleat connection is the standard field joint for rectangular duct sections, providing secure mechanical attachment.

Question 3

When fabricating a 90-degree elbow for round ductwork, what is the primary advantage of a gored elbow over a stamped elbow?

Accepted Answer

Lower airflow resistance

Answer

Gored elbows have a larger radius and fewer abrupt direction changes, resulting in lower static pressure loss compared to stamped elbows.

Question 4

What does the term 'flat pattern development' mean in sheet metal fabrication?

Accepted Answer

Laying out the 2D shape that will be bent into a 3D fitting

Answer

Flat pattern development is the process of calculating and drawing the unfolded shape of a fitting on flat sheet metal before cutting and forming.

Question 5

Which hand tool is used to close the Pittsburgh lock seam on rectangular duct?

Accepted Answer

Hammer and bar folder

Answer

A mallet and a bar folder or hand seamer are used to close the Pittsburgh lock seam by folding the male edge into the female pocket.

HVAC Practice Test