Newest 2026/2027 Louisiana (New Orleans) Second Class Stationary Boilers (661-
LA 661) exam verified with correct answers and rationales
1. What is the primary purpose of a boiler safety valve?
A. Increase steam pressure
B. Prevent excessive boiler pressure by automatically releasing steam
C. Improve combustion efficiency
D. Remove condensate
Correct Answer: B
Rationale: The safety valve is the boiler's primary overpressure protection device. It opens
automatically when pressure exceeds the set point.
2. What is the primary cause of scale formation inside a boiler?
A. Hard water containing calcium and magnesium
B. Excess oxygen in the water
C. Low steam pressure
D. High fuel consumption
Correct Answer: A
Rationale: Hard water minerals deposit on heating surfaces, reducing heat transfer and
increasing fuel consumption.
3. Which device indicates the water level inside a boiler?
A. Gauge glass (water column)
B. Thermostat
C. Pressure switch
D. Flow meter
Correct Answer: A
Rationale: The gauge glass allows the operator to visually monitor the boiler water level.
4. Low boiler water can result in:
,A. Overheating of boiler tubes
B. Improved efficiency
C. Lower fuel consumption
D. Reduced steam production only
Correct Answer: A
Rationale: Insufficient water exposes heating surfaces, causing overheating and possible boiler
failure.
5. What is the purpose of boiler blowdown?
A. Remove sludge and dissolved solids from the boiler
B. Increase steam pressure
C. Cool the furnace
D. Increase oxygen content
Correct Answer: A
Rationale: Blowdown controls dissolved solids and prevents scale formation.
6. Which chemical is commonly used to remove dissolved oxygen from boiler
water?
A. Sodium sulfite
B. Chlorine
C. Calcium carbonate
D. Hydrochloric acid
Correct Answer: A
Rationale: Sodium sulfite reacts with dissolved oxygen, reducing corrosion.
7. What is the purpose of a deaerator?
A. Remove dissolved oxygen and carbon dioxide from feedwater
B. Increase steam temperature
C. Raise fuel pressure
D. Reduce combustion air
, Correct Answer: A
Rationale: Deaerators reduce corrosion by removing dissolved gases before water enters the
boiler.
8. Which fuel requires the greatest amount of combustion air?
A. Natural gas
B. Fuel oil
C. Coal
D. All fuels require appropriate combustion air based on their composition
Correct Answer: D
Rationale: Every fuel has a specific theoretical air requirement for complete combustion.
9. Black smoke from the stack usually indicates:
A. Incomplete combustion due to insufficient air
B. Excessive water level
C. High feedwater temperature
D. Low steam pressure
Correct Answer: A
Rationale: Black smoke represents unburned carbon caused by inadequate combustion air.
10. Which instrument measures boiler pressure?
A. Pressure gauge
B. Thermometer
C. Hydrometer
D. Sight glass
Correct Answer: A
Rationale: Pressure gauges provide continuous pressure readings.
LA 661) exam verified with correct answers and rationales
1. What is the primary purpose of a boiler safety valve?
A. Increase steam pressure
B. Prevent excessive boiler pressure by automatically releasing steam
C. Improve combustion efficiency
D. Remove condensate
Correct Answer: B
Rationale: The safety valve is the boiler's primary overpressure protection device. It opens
automatically when pressure exceeds the set point.
2. What is the primary cause of scale formation inside a boiler?
A. Hard water containing calcium and magnesium
B. Excess oxygen in the water
C. Low steam pressure
D. High fuel consumption
Correct Answer: A
Rationale: Hard water minerals deposit on heating surfaces, reducing heat transfer and
increasing fuel consumption.
3. Which device indicates the water level inside a boiler?
A. Gauge glass (water column)
B. Thermostat
C. Pressure switch
D. Flow meter
Correct Answer: A
Rationale: The gauge glass allows the operator to visually monitor the boiler water level.
4. Low boiler water can result in:
,A. Overheating of boiler tubes
B. Improved efficiency
C. Lower fuel consumption
D. Reduced steam production only
Correct Answer: A
Rationale: Insufficient water exposes heating surfaces, causing overheating and possible boiler
failure.
5. What is the purpose of boiler blowdown?
A. Remove sludge and dissolved solids from the boiler
B. Increase steam pressure
C. Cool the furnace
D. Increase oxygen content
Correct Answer: A
Rationale: Blowdown controls dissolved solids and prevents scale formation.
6. Which chemical is commonly used to remove dissolved oxygen from boiler
water?
A. Sodium sulfite
B. Chlorine
C. Calcium carbonate
D. Hydrochloric acid
Correct Answer: A
Rationale: Sodium sulfite reacts with dissolved oxygen, reducing corrosion.
7. What is the purpose of a deaerator?
A. Remove dissolved oxygen and carbon dioxide from feedwater
B. Increase steam temperature
C. Raise fuel pressure
D. Reduce combustion air
, Correct Answer: A
Rationale: Deaerators reduce corrosion by removing dissolved gases before water enters the
boiler.
8. Which fuel requires the greatest amount of combustion air?
A. Natural gas
B. Fuel oil
C. Coal
D. All fuels require appropriate combustion air based on their composition
Correct Answer: D
Rationale: Every fuel has a specific theoretical air requirement for complete combustion.
9. Black smoke from the stack usually indicates:
A. Incomplete combustion due to insufficient air
B. Excessive water level
C. High feedwater temperature
D. Low steam pressure
Correct Answer: A
Rationale: Black smoke represents unburned carbon caused by inadequate combustion air.
10. Which instrument measures boiler pressure?
A. Pressure gauge
B. Thermometer
C. Hydrometer
D. Sight glass
Correct Answer: A
Rationale: Pressure gauges provide continuous pressure readings.
