Examination — Local Jurisdiction
Practice Exam 2026 | 100 Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1.
A rectangular supply duct is being installed in a long horizontal run. What is the
primary reason for installing properly spaced transverse joints and
reinforcement?
A. To increase airflow velocity
B. To reduce the duct's static pressure
C. To maintain the duct's structural rigidity and prevent excessive deflection
D. To eliminate the need for hangers
Answer: To maintain the duct's structural rigidity and prevent excessive
deflection
,Rationale: Proper reinforcement controls panel deflection, vibration, oil-
canning, and joint movement. It does not replace required supports or directly
increase airflow.
2.
When calculating the developed length of a rectangular sheet-metal fitting, why
must bend allowances be considered?
A. To determine insulation thickness
B. To compensate for material consumed by bending
C. To increase the gauge of the metal
D. To determine fan horsepower
Answer: To compensate for material consumed by bending
Rationale: Bending changes the neutral-axis geometry of the sheet. Bend
allowance or an equivalent fabrication method is necessary for accurate flat-
pattern development.
3.
A duct system has excessive leakage at several transverse joints. Which correction
is generally most appropriate?
A. Increase fan speed
B. Seal the joints using an approved duct-sealing method appropriate to the
pressure class
C. Remove all reinforcement
D. Reduce the duct size
Answer: Seal the joints using an approved duct-sealing method appropriate to
the pressure class
Rationale: Leakage is controlled through proper joint construction and approved
sealants or sealing systems selected for the duct pressure and application.
4.
,A rectangular duct has a high aspect ratio. What is a likely consequence of using
an unnecessarily wide and shallow duct instead of a more nearly square duct?
A. Lower surface area in all cases
B. Increased pressure loss and greater structural reinforcement requirements
C. Elimination of turbulence
D. Elimination of the need for turning vanes
Answer: Increased pressure loss and greater structural reinforcement
requirements
Rationale: High-aspect-ratio ducts generally have greater perimeter for a given
area and can require additional reinforcement, increasing both fabrication
complexity and system resistance.
5.
What is the principal function of turning vanes in a rectangular elbow?
A. Increase duct leakage
B. Reduce turbulence and pressure loss through the turn
C. Increase the duct's operating temperature
D. Replace flexible connectors
Answer: Reduce turbulence and pressure loss through the turn
Rationale: Properly designed turning vanes guide airflow through a rectangular
elbow and can reduce separation, turbulence, and fitting losses.
6.
A sheet-metal contractor discovers that a duct shown on the mechanical drawings
conflicts with a structural beam. What should be done first?
A. Cut the beam
B. Ignore the conflict and install the duct
C. Coordinate the conflict with the appropriate project parties before modifying
, the design
D. Reduce the duct gauge
Answer: Coordinate the conflict with the appropriate project parties before
modifying the design
Rationale: Field personnel should not independently modify structural elements
or alter engineered systems. Conflicts should be resolved through proper
coordination and approved changes.
7.
What is the main purpose of a flexible duct connector at an air-handling unit?
A. Increase system pressure
B. Isolate vibration and prevent transmission of equipment movement into rigid
ductwork
C. Replace equipment supports
D. Increase duct velocity
Answer: Isolate vibration and prevent transmission of equipment movement
into rigid ductwork
Rationale: Flexible connectors help isolate vibration and accommodate limited
equipment movement. They are not intended to support the equipment or
function as ordinary duct sections.
8.
A duct hanger is attached to a ceiling system that is not designed to support the
duct load. What is the primary concern?
A. Excessive airflow
B. Structural failure or damage to the ceiling assembly
C. Reduced duct temperature
D. Excessive filter loading
Answer: Structural failure or damage to the ceiling assembly