Michigan Sheet Metal Designer Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In sheet metal design, the primary purpose of a backdraft damper in a
ventilation system is to:
A. Increase fan static pressure
B. Prevent reverse airflow
C. Filter particulates from the airstream
D. Reduce sound transmission
The correct answer is bolded because a backdraft damper’s
fundamental function is to stop air from flowing backward through
the ductwork when the fan is off or under negative pressure,
ensuring proper airflow direction.
2. The minimum recommended clearance between uninsulated
rectangular ductwork and combustibles in a nonrated assembly is
typically:
A. 2 inches
B. 4 inches
C. 6 inches
D. 8 inches
The correct answer is bolded because building codes generally specify
at least a 2-inch clearance between non-insulated sheet metal ducts
and combustible materials to prevent heat transfer hazards.
3. When calculating static pressure loss in a duct system, which of the
following has the greatest impact on resistance?
A. Duct length
B. Duct size
, C. Ambient air temperature
D. Fan horsepower
The correct answer is bolded because duct diameter inversely affects
friction loss exponentially; smaller ducts dramatically increase
resistance compared to other listed factors.
4. A 90° elbow in a duct will cause:
A. Decreased turbulence
B. Higher airflow capacity
C. Increased pressure loss
D. Lower fan energy usage
The correct answer is bolded because sharp changes in direction
create turbulence and friction, which increase pressure loss in the
system.
5. In sheet metal gauge nomenclature, a higher gauge number indicates:
A. Thicker metal
B. Thinner metal
C. Higher tensile strength
D. Greater width
The correct answer is bolded because sheet metal gauge works
inversely; as the gauge number increases, the thickness of the metal
decreases.
6. Which of the following sheet metal seams is most appropriate for
low-pressure air distribution systems?
A. Pittsburgh
B. Snap lock
C. Welded
D. Riveted with sealant
The correct answer is bolded because snap lock seams provide
sufficient airtightness for low-pressure systems and are quick to
assemble.
7. When designing a rectangular duct, the most efficient cross-section
occurs when:
A. The perimeter is maximized
B. The aspect ratio is close to 1:1
C. Length is twice the width
, D. Height is half the width
The correct answer is bolded because near-square ducts minimize
surface area for a given cross-section, reducing friction loss and
material cost.
8. In HVAC sheet metal design, the term “CFM” refers to:
A. Cubic Foot Mass
B. Cubic Feet per Minute
C. Compressor Flow Measure
D. Coefficient of Friction
The correct answer is bolded because CFM is the standard unit for
measuring airflow rate, critical in duct sizing and equipment
selection.
9. A relief air configuration in rooftop units is used primarily to:
A. Increase supply air temperature
B. Prevent negative building pressure
C. Filter intake air
D. Reduce noise levels
The correct answer is bolded because relief air helps balance building
air pressure when exhaust exceeds makeup air.
10. The ideal airflow velocity in a main supply duct is generally
controlled to avoid:
A. Excess static pressure
B. Excessive noise and friction loss
C. Reduced filter efficiency
D. Increased humidity
The correct answer is bolded because high velocities can cause noise
and increase friction losses requiring more fan energy.
11. A plenum is best described as:
A. A type of fan
B. An air distribution chamber
C. A filter rack
D. A duct support
The correct answer is bolded because a plenum is an enclosed space
used to distribute conditioned air before it enters the branch ducts.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In sheet metal design, the primary purpose of a backdraft damper in a
ventilation system is to:
A. Increase fan static pressure
B. Prevent reverse airflow
C. Filter particulates from the airstream
D. Reduce sound transmission
The correct answer is bolded because a backdraft damper’s
fundamental function is to stop air from flowing backward through
the ductwork when the fan is off or under negative pressure,
ensuring proper airflow direction.
2. The minimum recommended clearance between uninsulated
rectangular ductwork and combustibles in a nonrated assembly is
typically:
A. 2 inches
B. 4 inches
C. 6 inches
D. 8 inches
The correct answer is bolded because building codes generally specify
at least a 2-inch clearance between non-insulated sheet metal ducts
and combustible materials to prevent heat transfer hazards.
3. When calculating static pressure loss in a duct system, which of the
following has the greatest impact on resistance?
A. Duct length
B. Duct size
, C. Ambient air temperature
D. Fan horsepower
The correct answer is bolded because duct diameter inversely affects
friction loss exponentially; smaller ducts dramatically increase
resistance compared to other listed factors.
4. A 90° elbow in a duct will cause:
A. Decreased turbulence
B. Higher airflow capacity
C. Increased pressure loss
D. Lower fan energy usage
The correct answer is bolded because sharp changes in direction
create turbulence and friction, which increase pressure loss in the
system.
5. In sheet metal gauge nomenclature, a higher gauge number indicates:
A. Thicker metal
B. Thinner metal
C. Higher tensile strength
D. Greater width
The correct answer is bolded because sheet metal gauge works
inversely; as the gauge number increases, the thickness of the metal
decreases.
6. Which of the following sheet metal seams is most appropriate for
low-pressure air distribution systems?
A. Pittsburgh
B. Snap lock
C. Welded
D. Riveted with sealant
The correct answer is bolded because snap lock seams provide
sufficient airtightness for low-pressure systems and are quick to
assemble.
7. When designing a rectangular duct, the most efficient cross-section
occurs when:
A. The perimeter is maximized
B. The aspect ratio is close to 1:1
C. Length is twice the width
, D. Height is half the width
The correct answer is bolded because near-square ducts minimize
surface area for a given cross-section, reducing friction loss and
material cost.
8. In HVAC sheet metal design, the term “CFM” refers to:
A. Cubic Foot Mass
B. Cubic Feet per Minute
C. Compressor Flow Measure
D. Coefficient of Friction
The correct answer is bolded because CFM is the standard unit for
measuring airflow rate, critical in duct sizing and equipment
selection.
9. A relief air configuration in rooftop units is used primarily to:
A. Increase supply air temperature
B. Prevent negative building pressure
C. Filter intake air
D. Reduce noise levels
The correct answer is bolded because relief air helps balance building
air pressure when exhaust exceeds makeup air.
10. The ideal airflow velocity in a main supply duct is generally
controlled to avoid:
A. Excess static pressure
B. Excessive noise and friction loss
C. Reduced filter efficiency
D. Increased humidity
The correct answer is bolded because high velocities can cause noise
and increase friction losses requiring more fan energy.
11. A plenum is best described as:
A. A type of fan
B. An air distribution chamber
C. A filter rack
D. A duct support
The correct answer is bolded because a plenum is an enclosed space
used to distribute conditioned air before it enters the branch ducts.
