South Carolina Boiler Service Technician
License Exam Practice Questions And
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Rationale 2026 Q&A| Instant Download
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1. A low-pressure steam boiler in South Carolina must be equipped with
a safety relief valve set to open at what maximum pressure?
A. 10 psi
B. 15 psi
C. 30 psi
D. 50 psi
Rationale: Low-pressure steam boilers are limited to a maximum of
15 psi steam and the safety valve must be set to open at that
pressure to comply with code.
2. Which of the following ASME code sections governs the construction
of stationary boilers?
A. Section I
B. Section IV
C. Section VIII
D. Section IX
Rationale: ASME Section IV covers the construction of heating boilers
and hot water supply boilers typically used in building heating
systems.
3. What is the primary purpose of a boiler’s feedwater economizer?
A. To reduce combustion air requirements
B. To increase fuel volatility
, C. To recover heat from flue gases and preheat feedwater
D. To control water level in the boiler
Rationale: An economizer captures residual heat in the flue gases to
raise the temperature of incoming feedwater, improving overall
efficiency.
4. In South Carolina, a boiler technician must verify the operation of the
low-water cutoff on a steam boiler because failure of this device can
result in what condition?
A. Excessive draft
B. Boiler dry firing and serious damage
C. High fuel consumption only
D. Pump cavitation
Rationale: A low-water cutoff prevents the boiler from firing when
water level is too low; without it, the boiler can overheat and suffer
severe damage.
5. Which gas detector type is most appropriate for monitoring oxygen
deficiency near combustion equipment?
A. Catalytic bead sensor
B. Electrochemical oxygen sensor
C. Infrared hydrocarbon sensor
D. Photoionization detector
Rationale: Electrochemical sensors are specifically designed to detect
oxygen levels to protect against asphyxiation hazards around
combustion equipment.
6. The flame safeguard control on a boiler is intended to:
A. Reduce stack temperatures
B. Balance fuel/air ratio continuously
C. Prevent fuel flow without proven ignition
D. Circulate feedwater
Rationale: Flame safeguard controls ensure fuel is only delivered
when ignition and flame presence can be confirmed for safety.
7. What is the minimum clearance required between a boiler and a
combustible wall when no protection is provided?
A. 6 inches
B. 12 inches
, C. 24 inches
D. 36 inches
Rationale: Safety codes require 24 inches clearance between boilers
and combustible materials unless protective shielding is used.
8. A pressure gauge on a boiler must be calibrated to within what
percent of actual pressure?
A. ±2%
B. ±4%
C. ±3%
D. ±5%
Rationale: Codes typically require pressure gauges to have an
accuracy of ±3% of the span to ensure proper monitoring and safety.
9. In boiler combustion, what is the primary effect of excess air beyond
the stoichiometric amount?
A. Reduced stack gas volume
B. Higher combustion temperature
C. Lower thermal efficiency
D. Increased fuel volatility
Rationale: Excess air cools the flame and carries heat out the stack,
reducing burner thermal efficiency.
10. When venting a gas-fired boiler, the vent connector must:
A. Terminate below the draft hood outlet
B. Be as short and direct as practicable
C. Increase in size away from the boiler
D. Be made of rubber hose
Rationale: Vent connectors should be kept short and direct to
promote proper draft and minimize flow resistance.
11. Which device prevents backfiring into the burner in forced-draft
boilers?
A. Blower damper
B. Low-water cutoff
C. Backflow preventer or check valve in fuel line
D. Air aspirator
Rationale: A check valve prevents reverse flow of fuel that can lead
to backfire conditions.
License Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download
1. A low-pressure steam boiler in South Carolina must be equipped with
a safety relief valve set to open at what maximum pressure?
A. 10 psi
B. 15 psi
C. 30 psi
D. 50 psi
Rationale: Low-pressure steam boilers are limited to a maximum of
15 psi steam and the safety valve must be set to open at that
pressure to comply with code.
2. Which of the following ASME code sections governs the construction
of stationary boilers?
A. Section I
B. Section IV
C. Section VIII
D. Section IX
Rationale: ASME Section IV covers the construction of heating boilers
and hot water supply boilers typically used in building heating
systems.
3. What is the primary purpose of a boiler’s feedwater economizer?
A. To reduce combustion air requirements
B. To increase fuel volatility
, C. To recover heat from flue gases and preheat feedwater
D. To control water level in the boiler
Rationale: An economizer captures residual heat in the flue gases to
raise the temperature of incoming feedwater, improving overall
efficiency.
4. In South Carolina, a boiler technician must verify the operation of the
low-water cutoff on a steam boiler because failure of this device can
result in what condition?
A. Excessive draft
B. Boiler dry firing and serious damage
C. High fuel consumption only
D. Pump cavitation
Rationale: A low-water cutoff prevents the boiler from firing when
water level is too low; without it, the boiler can overheat and suffer
severe damage.
5. Which gas detector type is most appropriate for monitoring oxygen
deficiency near combustion equipment?
A. Catalytic bead sensor
B. Electrochemical oxygen sensor
C. Infrared hydrocarbon sensor
D. Photoionization detector
Rationale: Electrochemical sensors are specifically designed to detect
oxygen levels to protect against asphyxiation hazards around
combustion equipment.
6. The flame safeguard control on a boiler is intended to:
A. Reduce stack temperatures
B. Balance fuel/air ratio continuously
C. Prevent fuel flow without proven ignition
D. Circulate feedwater
Rationale: Flame safeguard controls ensure fuel is only delivered
when ignition and flame presence can be confirmed for safety.
7. What is the minimum clearance required between a boiler and a
combustible wall when no protection is provided?
A. 6 inches
B. 12 inches
, C. 24 inches
D. 36 inches
Rationale: Safety codes require 24 inches clearance between boilers
and combustible materials unless protective shielding is used.
8. A pressure gauge on a boiler must be calibrated to within what
percent of actual pressure?
A. ±2%
B. ±4%
C. ±3%
D. ±5%
Rationale: Codes typically require pressure gauges to have an
accuracy of ±3% of the span to ensure proper monitoring and safety.
9. In boiler combustion, what is the primary effect of excess air beyond
the stoichiometric amount?
A. Reduced stack gas volume
B. Higher combustion temperature
C. Lower thermal efficiency
D. Increased fuel volatility
Rationale: Excess air cools the flame and carries heat out the stack,
reducing burner thermal efficiency.
10. When venting a gas-fired boiler, the vent connector must:
A. Terminate below the draft hood outlet
B. Be as short and direct as practicable
C. Increase in size away from the boiler
D. Be made of rubber hose
Rationale: Vent connectors should be kept short and direct to
promote proper draft and minimize flow resistance.
11. Which device prevents backfiring into the burner in forced-draft
boilers?
A. Blower damper
B. Low-water cutoff
C. Backflow preventer or check valve in fuel line
D. Air aspirator
Rationale: A check valve prevents reverse flow of fuel that can lead
to backfire conditions.
