Hawaii Sheet Metal Contractor (C-44)
Examination Practice Exam 2026 | 100
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. A rectangular supply duct operates at a pressure class substantially higher
than originally anticipated. The installed duct has minimal reinforcement
and shows panel deflection. What is the best corrective approach?
A. Increase fan speed to stabilize the panels
B. Add insulation to the exterior only
C. Evaluate the duct against the applicable pressure class and provide engineered
reinforcement or replacement as required
D. Seal only the transverse joints
Answer: C. Evaluate the duct against the applicable pressure class and provide
engineered reinforcement or replacement as required
Rationale: Duct reinforcement must correspond to pressure, dimensions,
material, and construction method. Simply increasing fan speed or adding
insulation does not correct structural inadequacy.
, 2. A duct carries 2,400 CFM through a rectangular cross-sectional area of 4 ft².
What is its approximate average velocity?
A. 400 FPM
B. 600 FPM
C. 800 FPM
D. 1,200 FPM
Answer: B. 600 FPM
Rationale: Velocity is approximately CFM divided by area. Therefore, 2,400 ÷ 4 =
600 FPM.
3. A rectangular duct elbow has no turning vanes and produces excessive
turbulence and pressure loss. Which modification is most appropriate?
A. Reduce the elbow radius to zero
B. Install properly designed turning vanes where permitted
C. Reduce the duct width immediately before the elbow
D. Increase the number of branch dampers
Answer: B. Install properly designed turning vanes where permitted
Rationale: Turning vanes can provide a more controlled airflow path through
rectangular elbows and reduce turbulence and pressure loss when properly
selected and installed.
4. A high-pressure duct system has numerous unsealed longitudinal seams.
Which consequence is most likely?
A. Lower leakage and reduced fan load
B. Excessive air leakage and increased system energy consumption
C. Automatic balancing of the system
D. Increased insulation R-value
Answer: B. Excessive air leakage and increased system energy consumption
,Rationale: Higher-pressure systems are particularly sensitive to leakage because
leakage increases the amount of fan energy required to deliver the intended
airflow.
5. A duct transition changes from a large rectangular section to a much
smaller section over a very short distance. Which problem is most likely?
A. Reduced turbulence
B. Increased pressure loss and flow separation
C. Elimination of velocity pressure
D. Improved acoustic performance
Answer: B. Increased pressure loss and flow separation
Rationale: Abrupt transitions can produce turbulence, separation, and excessive
pressure loss. Properly proportioned transitions provide smoother airflow.
6. A supply duct carries 3,000 CFM at 750 FPM. What approximate cross-
sectional area is required?
A. 2 ft²
B. 3 ft²
C. 4 ft²
D. 5 ft²
Answer: C. 4 ft²
Rationale: Area = CFM ÷ velocity. Thus, 3,000 ÷ 750 = 4 ft².
7. Which change generally increases frictional pressure loss in a duct system?
A. Increasing duct diameter
B. Decreasing surface roughness
C. Increasing airflow velocity
D. Eliminating unnecessary fittings
Answer: C. Increasing airflow velocity
, Rationale: Frictional and dynamic losses generally increase as airflow velocity
increases.
8. A branch duct is receiving substantially less airflow than the design
documents indicate. The main duct pressure is adequate. Which condition
should be investigated first?
A. Branch damper position and downstream restrictions
B. Roof flashing
C. Duct insulation color
D. Sheet-metal gauge of an unrelated exhaust duct
Answer: A. Branch damper position and downstream restrictions
Rationale: A closed or partially closed damper, obstruction, excessive fitting
resistance, or incorrect branch configuration can restrict airflow even when
upstream pressure is adequate.
9. What is the primary purpose of a balancing damper in a branch duct?
A. Provide structural support
B. Regulate branch airflow
C. Prevent all smoke movement
D. Replace the supply diffuser
Answer: B. Regulate branch airflow
Rationale: Balancing dampers introduce adjustable resistance so that branch
airflow can be brought into the desired range during testing and balancing.
10.A duct system has adequate airflow at the fan but insufficient airflow at
distant terminals. Which system characteristic should be evaluated?
A. Total system pressure losses and distribution balance
B. Exterior paint thickness
C. Roof color
D. Electrical conduit color
Examination Practice Exam 2026 | 100
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. A rectangular supply duct operates at a pressure class substantially higher
than originally anticipated. The installed duct has minimal reinforcement
and shows panel deflection. What is the best corrective approach?
A. Increase fan speed to stabilize the panels
B. Add insulation to the exterior only
C. Evaluate the duct against the applicable pressure class and provide engineered
reinforcement or replacement as required
D. Seal only the transverse joints
Answer: C. Evaluate the duct against the applicable pressure class and provide
engineered reinforcement or replacement as required
Rationale: Duct reinforcement must correspond to pressure, dimensions,
material, and construction method. Simply increasing fan speed or adding
insulation does not correct structural inadequacy.
, 2. A duct carries 2,400 CFM through a rectangular cross-sectional area of 4 ft².
What is its approximate average velocity?
A. 400 FPM
B. 600 FPM
C. 800 FPM
D. 1,200 FPM
Answer: B. 600 FPM
Rationale: Velocity is approximately CFM divided by area. Therefore, 2,400 ÷ 4 =
600 FPM.
3. A rectangular duct elbow has no turning vanes and produces excessive
turbulence and pressure loss. Which modification is most appropriate?
A. Reduce the elbow radius to zero
B. Install properly designed turning vanes where permitted
C. Reduce the duct width immediately before the elbow
D. Increase the number of branch dampers
Answer: B. Install properly designed turning vanes where permitted
Rationale: Turning vanes can provide a more controlled airflow path through
rectangular elbows and reduce turbulence and pressure loss when properly
selected and installed.
4. A high-pressure duct system has numerous unsealed longitudinal seams.
Which consequence is most likely?
A. Lower leakage and reduced fan load
B. Excessive air leakage and increased system energy consumption
C. Automatic balancing of the system
D. Increased insulation R-value
Answer: B. Excessive air leakage and increased system energy consumption
,Rationale: Higher-pressure systems are particularly sensitive to leakage because
leakage increases the amount of fan energy required to deliver the intended
airflow.
5. A duct transition changes from a large rectangular section to a much
smaller section over a very short distance. Which problem is most likely?
A. Reduced turbulence
B. Increased pressure loss and flow separation
C. Elimination of velocity pressure
D. Improved acoustic performance
Answer: B. Increased pressure loss and flow separation
Rationale: Abrupt transitions can produce turbulence, separation, and excessive
pressure loss. Properly proportioned transitions provide smoother airflow.
6. A supply duct carries 3,000 CFM at 750 FPM. What approximate cross-
sectional area is required?
A. 2 ft²
B. 3 ft²
C. 4 ft²
D. 5 ft²
Answer: C. 4 ft²
Rationale: Area = CFM ÷ velocity. Thus, 3,000 ÷ 750 = 4 ft².
7. Which change generally increases frictional pressure loss in a duct system?
A. Increasing duct diameter
B. Decreasing surface roughness
C. Increasing airflow velocity
D. Eliminating unnecessary fittings
Answer: C. Increasing airflow velocity
, Rationale: Frictional and dynamic losses generally increase as airflow velocity
increases.
8. A branch duct is receiving substantially less airflow than the design
documents indicate. The main duct pressure is adequate. Which condition
should be investigated first?
A. Branch damper position and downstream restrictions
B. Roof flashing
C. Duct insulation color
D. Sheet-metal gauge of an unrelated exhaust duct
Answer: A. Branch damper position and downstream restrictions
Rationale: A closed or partially closed damper, obstruction, excessive fitting
resistance, or incorrect branch configuration can restrict airflow even when
upstream pressure is adequate.
9. What is the primary purpose of a balancing damper in a branch duct?
A. Provide structural support
B. Regulate branch airflow
C. Prevent all smoke movement
D. Replace the supply diffuser
Answer: B. Regulate branch airflow
Rationale: Balancing dampers introduce adjustable resistance so that branch
airflow can be brought into the desired range during testing and balancing.
10.A duct system has adequate airflow at the fan but insufficient airflow at
distant terminals. Which system characteristic should be evaluated?
A. Total system pressure losses and distribution balance
B. Exterior paint thickness
C. Roof color
D. Electrical conduit color
