Ultimate Maryland Stationary Engineer Grade 1 Exam
Preparation 2026–2027 (150 Practice Questions &
Answers with Full Explanations | Boiler Plant
Operation, Maintenance, Safety & Troubleshooting
Mastery Test Bank)
SECTION 1: BOILER OPERATION & COMBUSTION (Questions 1–20)
1. What is the maximum horsepower (HP) a Grade 1 stationary engineer is authorized to
operate in Maryland?
A) 300 HP
B) 499 HP
C) 500 HP or more
D) 100 HP
Explanation: A Grade 1 license is the highest level and allows operation of boilers and
equipment with 500 horsepower or more. Lower grades have lower HP limits.
2. What is the primary purpose of a boiler safety valve?
A) Control steam temperature
B) Prevent overpressure and possible explosion
C) Regulate fuel flow
D) Monitor water chemistry
Explanation: The safety valve is a critical safety device designed to automatically relieve
pressure when it exceeds the maximum allowable working pressure (MAWP), preventing
catastrophic failure.
3. During boiler startup, which action is critical BEFORE introducing fuel to the burner?
A) Open the blowdown valve
, B) Verify adequate water level in the gauge glass
C) Close all steam outlet valves
D) Increase combustion air
Explanation: Firing a boiler without sufficient water can cause severe damage, including
tube failure and explosion. The water level must be visibly confirmed in the gauge glass.
4. What is the function of a low-water fuel cutoff?
A) Reduce fuel pressure
B) Shut off fuel supply when water level drops below safe limits
C) Increase feedwater flow
D) Control steam pressure
Explanation: A low-water fuel cutoff is a safety device that interrupts the fuel supply if water
level falls to a dangerous point, preventing boiler overheating and failure.
5. What is the recommended maximum total dissolved solids (TDS) range for a fire-tube
boiler?
A) 50–100 ppm
B) 200–500 ppm
C) 2,500–3,500 ppm
D) 10,000–15,000 ppm
Explanation: High TDS leads to foaming, carryover, and scale. Typical boiler water TDS
limits are between 2,500 and 3,500 ppm, depending on operating pressure and boiler type.
6. What does a flame scanner detect in a burner management system?
A) Fuel pressure
B) Presence or absence of flame
C) Combustion air temperature
D) Stack opacity
Explanation: Flame scanners are optical or ultraviolet sensors that confirm flame presence.
If flame is lost, the system initiates a safety shutdown.
, 7. Which boiler type is most common for high-pressure, high-capacity applications?
A) Cast iron sectional
B) Fire-tube scotch marine
C) Water-tube boiler
D) Electric boiler
Explanation: Water-tube boilers are used for high-pressure and high-capacity applications
because water circulates inside tubes, allowing rapid steam generation and handling higher
pressures.
8. What is the purpose of a deaerator in a boiler system?
A) Increase steam temperature
B) Remove dissolved oxygen and non-condensable gases
C) Reduce fuel consumption
D) Control steam pressure
Explanation: Deaerators use heat and mechanical action to remove oxygen and carbon
dioxide from feedwater, preventing corrosion in the boiler and piping.
9. What action should be taken if a boiler safety valve fails to open at its set pressure?
A) Increase boiler pressure to force it open
B) Shut down the boiler and repair or replace the valve
C) Tap the valve with a hammer
D) Continue operation but monitor pressure closely
Explanation: A stuck safety valve is a critical hazard. The boiler must be taken offline
immediately to repair or replace the valve before resuming operation.
10. What is the function of a burner management system (BMS)?
A) Adjust fuel viscosity
B) Control safe startup, operation, and shutdown of burners
C) Monitor stack emissions
D) Regulate feedwater temperature
, Explanation: The BMS ensures proper purging, ignition sequencing, flame monitoring, and
safety interlocks to prevent unsafe conditions during burner operation.
11. What is the purpose of a steam trap?
A) Trap steam in the system
B) Remove condensate and non-condensable gases while retaining steam
C) Reduce steam pressure
D) Increase steam temperature
Explanation: Steam traps automatically discharge condensate and air while preventing
steam loss, improving system efficiency and preventing water hammer.
12. What is the most common cause of boiler furnace explosions?
A) High feedwater temperature
B) Improper purging before ignition
C) Low steam pressure
D) Excessive blowdown
Explanation: Accumulated unburned fuel in the furnace can ignite explosively. A proper
pre-purge cycle (typically 5–10 air changes) is essential to clear combustible gases.
13. What does the term "carryover" refer to?
A) Loss of flame during operation
B) Water and impurities carried with steam into the distribution system
C) Excess fuel in the combustion chamber
D) Overpressure condition
Explanation: Carryover occurs when boiler water droplets, containing dissolved solids, are
entrained in steam, causing fouling of valves, turbines, and piping.
14. Which chemical is commonly used for oxygen scavenging in boiler feedwater?
A) Sodium hydroxide
B) Sodium sulfite
C) Calcium carbonate
D) Phosphoric acid
Preparation 2026–2027 (150 Practice Questions &
Answers with Full Explanations | Boiler Plant
Operation, Maintenance, Safety & Troubleshooting
Mastery Test Bank)
SECTION 1: BOILER OPERATION & COMBUSTION (Questions 1–20)
1. What is the maximum horsepower (HP) a Grade 1 stationary engineer is authorized to
operate in Maryland?
A) 300 HP
B) 499 HP
C) 500 HP or more
D) 100 HP
Explanation: A Grade 1 license is the highest level and allows operation of boilers and
equipment with 500 horsepower or more. Lower grades have lower HP limits.
2. What is the primary purpose of a boiler safety valve?
A) Control steam temperature
B) Prevent overpressure and possible explosion
C) Regulate fuel flow
D) Monitor water chemistry
Explanation: The safety valve is a critical safety device designed to automatically relieve
pressure when it exceeds the maximum allowable working pressure (MAWP), preventing
catastrophic failure.
3. During boiler startup, which action is critical BEFORE introducing fuel to the burner?
A) Open the blowdown valve
, B) Verify adequate water level in the gauge glass
C) Close all steam outlet valves
D) Increase combustion air
Explanation: Firing a boiler without sufficient water can cause severe damage, including
tube failure and explosion. The water level must be visibly confirmed in the gauge glass.
4. What is the function of a low-water fuel cutoff?
A) Reduce fuel pressure
B) Shut off fuel supply when water level drops below safe limits
C) Increase feedwater flow
D) Control steam pressure
Explanation: A low-water fuel cutoff is a safety device that interrupts the fuel supply if water
level falls to a dangerous point, preventing boiler overheating and failure.
5. What is the recommended maximum total dissolved solids (TDS) range for a fire-tube
boiler?
A) 50–100 ppm
B) 200–500 ppm
C) 2,500–3,500 ppm
D) 10,000–15,000 ppm
Explanation: High TDS leads to foaming, carryover, and scale. Typical boiler water TDS
limits are between 2,500 and 3,500 ppm, depending on operating pressure and boiler type.
6. What does a flame scanner detect in a burner management system?
A) Fuel pressure
B) Presence or absence of flame
C) Combustion air temperature
D) Stack opacity
Explanation: Flame scanners are optical or ultraviolet sensors that confirm flame presence.
If flame is lost, the system initiates a safety shutdown.
, 7. Which boiler type is most common for high-pressure, high-capacity applications?
A) Cast iron sectional
B) Fire-tube scotch marine
C) Water-tube boiler
D) Electric boiler
Explanation: Water-tube boilers are used for high-pressure and high-capacity applications
because water circulates inside tubes, allowing rapid steam generation and handling higher
pressures.
8. What is the purpose of a deaerator in a boiler system?
A) Increase steam temperature
B) Remove dissolved oxygen and non-condensable gases
C) Reduce fuel consumption
D) Control steam pressure
Explanation: Deaerators use heat and mechanical action to remove oxygen and carbon
dioxide from feedwater, preventing corrosion in the boiler and piping.
9. What action should be taken if a boiler safety valve fails to open at its set pressure?
A) Increase boiler pressure to force it open
B) Shut down the boiler and repair or replace the valve
C) Tap the valve with a hammer
D) Continue operation but monitor pressure closely
Explanation: A stuck safety valve is a critical hazard. The boiler must be taken offline
immediately to repair or replace the valve before resuming operation.
10. What is the function of a burner management system (BMS)?
A) Adjust fuel viscosity
B) Control safe startup, operation, and shutdown of burners
C) Monitor stack emissions
D) Regulate feedwater temperature
, Explanation: The BMS ensures proper purging, ignition sequencing, flame monitoring, and
safety interlocks to prevent unsafe conditions during burner operation.
11. What is the purpose of a steam trap?
A) Trap steam in the system
B) Remove condensate and non-condensable gases while retaining steam
C) Reduce steam pressure
D) Increase steam temperature
Explanation: Steam traps automatically discharge condensate and air while preventing
steam loss, improving system efficiency and preventing water hammer.
12. What is the most common cause of boiler furnace explosions?
A) High feedwater temperature
B) Improper purging before ignition
C) Low steam pressure
D) Excessive blowdown
Explanation: Accumulated unburned fuel in the furnace can ignite explosively. A proper
pre-purge cycle (typically 5–10 air changes) is essential to clear combustible gases.
13. What does the term "carryover" refer to?
A) Loss of flame during operation
B) Water and impurities carried with steam into the distribution system
C) Excess fuel in the combustion chamber
D) Overpressure condition
Explanation: Carryover occurs when boiler water droplets, containing dissolved solids, are
entrained in steam, causing fouling of valves, turbines, and piping.
14. Which chemical is commonly used for oxygen scavenging in boiler feedwater?
A) Sodium hydroxide
B) Sodium sulfite
C) Calcium carbonate
D) Phosphoric acid
