641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
Question 1. What is the primary difference between fire-tube and water-tube boilers?
A) Fire-tube boilers have tubes filled with water inside a fire chamber, while water-tube boilers have
tubes filled with fire inside a water chamber.
B) Fire-tube boilers have hot gases passing through tubes surrounded by water, whereas water-tube
boilers have water passing through tubes heated externally by combustion gases.
C) Fire-tube boilers are used only for high-pressure applications, while water-tube boilers are used for
low-pressure applications.
D) Fire-tube boilers are more efficient than water-tube boilers in all applications.
Answer: B
Explanation: In fire-tube boilers, hot gases flow through tubes surrounded by water, while in water-tube
boilers, water flows through tubes heated externally by combustion gases, making B the correct choice.
Question 2. Which component is primarily responsible for preventing boiler overpressure?
A) Low-water cutoff
B) Safety relief valve
C) Feedwater pump
D) Air vent
Answer: B
Explanation: The safety relief valve is designed to release excess pressure to prevent overpressure
conditions in the boiler, ensuring safety.
Question 3. What does a boiler horsepower (BHP) measure?
A) The maximum pressure a boiler can handle
B) The heat transfer rate equivalent to the amount of water evaporated per hour
C) The mechanical power output of the boiler’s turbine
D) The fuel consumption rate of the boiler
Answer: B
Explanation: Boiler horsepower measures the heat transfer capacity, specifically the amount of water
evaporated at 212°F per hour, making B correct.
, 641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
Question 4. Which safety device is most critical in protecting against excessive pressure buildup?
A) Water column
B) Pressure relief valve
C) Low-water cutoff
D) Manometer
Answer: B
Explanation: The pressure relief valve automatically opens to release pressure when it exceeds safe
limits, preventing potential explosions.
Question 5. What is the primary purpose of a low-water cutoff in a boiler?
A) To regulate fuel supply
B) To prevent operation when water level is too low, avoiding boiler damage
C) To control the temperature of the steam
D) To release excess pressure
Answer: B
Explanation: The low-water cutoff shuts down the boiler if water levels fall below a safe point,
protecting against dry firing and damage.
Question 6. Which fuel type is characterized by a high energy content and is commonly used in large
industrial boilers?
A) Natural gas
B) Fuel oil
C) Coal
D) Propane
Answer: C
Explanation: Coal has a high energy content per unit weight and is often used in large-scale industrial
boilers due to its availability and cost-effectiveness.
Question 7. Which combustion element is NOT typically controlled to optimize boiler efficiency?
A) Air supply
, 641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
B) Fuel feed rate
C) Water temperature
D) Combustion turbulence
Answer: C
Explanation: While air supply and fuel rate are actively controlled, water temperature is not directly
managed in combustion control; turbulence is an operational factor.
Question 8. What is the primary advantage of using a water-tube boiler over a fire-tube boiler?
A) Higher pressure capability and faster steam generation
B) Simpler construction and lower initial cost
C) Better suited for small-scale applications
D) Less maintenance required
Answer: A
Explanation: Water-tube boilers can operate at higher pressures and generate steam more quickly,
which is advantageous for large or high-pressure applications.
Question 9. Which water treatment process is used to remove calcium and magnesium ions that cause
hardness?
A) Softening with zeolite
B) Reverse osmosis
C) Filtration
D) Alkaline treatment
Answer: A
Explanation: Zeolite softening exchanges calcium and magnesium ions with sodium, removing hardness-
causing minerals.
Question 10. What is the purpose of blowdown in a boiler system?
A) To remove accumulated impurities and maintain water quality
B) To release excess pressure
C) To increase water level
, 641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
D) To control combustion efficiency
Answer: A
Explanation: Blowdown removes concentrated impurities and sludge from the boiler, maintaining water
quality and preventing scale buildup.
Question 11. Which of the following is a common cause of tube leaks in a boiler?
A) Excessive water flow
B) Corrosion or thermal stress
C) Low fuel pressure
D) Overpressure relief valve malfunction
Answer: B
Explanation: Corrosion and thermal stress weaken tube material, leading to leaks and potential failure.
Question 12. During a routine inspection, which safety device should be tested to ensure proper
operation?
A) Feedwater pump
B) Safety relief valve
C) Main steam stop valve
D) Water level gauge
Answer: B
Explanation: Safety relief valves must be tested periodically to verify proper opening pressure and
functionality to ensure safety.
Question 13. What is the primary function of a deaerator in a boiler system?
A) To remove dissolved oxygen and carbon dioxide from feedwater
B) To increase water temperature before entering the boiler
C) To add chemicals to the feedwater
D) To regulate pressure in the feedwater line
Answer: A
Boilers Exam
Question 1. What is the primary difference between fire-tube and water-tube boilers?
A) Fire-tube boilers have tubes filled with water inside a fire chamber, while water-tube boilers have
tubes filled with fire inside a water chamber.
B) Fire-tube boilers have hot gases passing through tubes surrounded by water, whereas water-tube
boilers have water passing through tubes heated externally by combustion gases.
C) Fire-tube boilers are used only for high-pressure applications, while water-tube boilers are used for
low-pressure applications.
D) Fire-tube boilers are more efficient than water-tube boilers in all applications.
Answer: B
Explanation: In fire-tube boilers, hot gases flow through tubes surrounded by water, while in water-tube
boilers, water flows through tubes heated externally by combustion gases, making B the correct choice.
Question 2. Which component is primarily responsible for preventing boiler overpressure?
A) Low-water cutoff
B) Safety relief valve
C) Feedwater pump
D) Air vent
Answer: B
Explanation: The safety relief valve is designed to release excess pressure to prevent overpressure
conditions in the boiler, ensuring safety.
Question 3. What does a boiler horsepower (BHP) measure?
A) The maximum pressure a boiler can handle
B) The heat transfer rate equivalent to the amount of water evaporated per hour
C) The mechanical power output of the boiler’s turbine
D) The fuel consumption rate of the boiler
Answer: B
Explanation: Boiler horsepower measures the heat transfer capacity, specifically the amount of water
evaporated at 212°F per hour, making B correct.
, 641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
Question 4. Which safety device is most critical in protecting against excessive pressure buildup?
A) Water column
B) Pressure relief valve
C) Low-water cutoff
D) Manometer
Answer: B
Explanation: The pressure relief valve automatically opens to release pressure when it exceeds safe
limits, preventing potential explosions.
Question 5. What is the primary purpose of a low-water cutoff in a boiler?
A) To regulate fuel supply
B) To prevent operation when water level is too low, avoiding boiler damage
C) To control the temperature of the steam
D) To release excess pressure
Answer: B
Explanation: The low-water cutoff shuts down the boiler if water levels fall below a safe point,
protecting against dry firing and damage.
Question 6. Which fuel type is characterized by a high energy content and is commonly used in large
industrial boilers?
A) Natural gas
B) Fuel oil
C) Coal
D) Propane
Answer: C
Explanation: Coal has a high energy content per unit weight and is often used in large-scale industrial
boilers due to its availability and cost-effectiveness.
Question 7. Which combustion element is NOT typically controlled to optimize boiler efficiency?
A) Air supply
, 641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
B) Fuel feed rate
C) Water temperature
D) Combustion turbulence
Answer: C
Explanation: While air supply and fuel rate are actively controlled, water temperature is not directly
managed in combustion control; turbulence is an operational factor.
Question 8. What is the primary advantage of using a water-tube boiler over a fire-tube boiler?
A) Higher pressure capability and faster steam generation
B) Simpler construction and lower initial cost
C) Better suited for small-scale applications
D) Less maintenance required
Answer: A
Explanation: Water-tube boilers can operate at higher pressures and generate steam more quickly,
which is advantageous for large or high-pressure applications.
Question 9. Which water treatment process is used to remove calcium and magnesium ions that cause
hardness?
A) Softening with zeolite
B) Reverse osmosis
C) Filtration
D) Alkaline treatment
Answer: A
Explanation: Zeolite softening exchanges calcium and magnesium ions with sodium, removing hardness-
causing minerals.
Question 10. What is the purpose of blowdown in a boiler system?
A) To remove accumulated impurities and maintain water quality
B) To release excess pressure
C) To increase water level
, 641 LA 641 Louisiana New Orleans Third Class Stationary
Boilers Exam
D) To control combustion efficiency
Answer: A
Explanation: Blowdown removes concentrated impurities and sludge from the boiler, maintaining water
quality and preventing scale buildup.
Question 11. Which of the following is a common cause of tube leaks in a boiler?
A) Excessive water flow
B) Corrosion or thermal stress
C) Low fuel pressure
D) Overpressure relief valve malfunction
Answer: B
Explanation: Corrosion and thermal stress weaken tube material, leading to leaks and potential failure.
Question 12. During a routine inspection, which safety device should be tested to ensure proper
operation?
A) Feedwater pump
B) Safety relief valve
C) Main steam stop valve
D) Water level gauge
Answer: B
Explanation: Safety relief valves must be tested periodically to verify proper opening pressure and
functionality to ensure safety.
Question 13. What is the primary function of a deaerator in a boiler system?
A) To remove dissolved oxygen and carbon dioxide from feedwater
B) To increase water temperature before entering the boiler
C) To add chemicals to the feedwater
D) To regulate pressure in the feedwater line
Answer: A
