Illinois Stationary Engineer Examination,
Practice Questions With Correct Answers
(Verified Answers) Plus Rationales
1. What is the main purpose of a boiler’s safety valve?
A. To control fuel supply
B. To release excess pressure
C. To monitor water level
D. To regulate temperature
Safety valves prevent boilers from exceeding maximum pressure,
avoiding explosions.
2. What type of fuel is most commonly used in large industrial
boilers?
A. Coal
B. Natural gas
C. Wood
D. Diesel
Natural gas is preferred for its efficiency and cleaner combustion.
3. What does a deaerator remove from boiler feedwater?
A. Solids
B. Dissolved gases
C. Oil
D. Bacteria
, Dissolved oxygen and carbon dioxide are removed to prevent
corrosion.
4. What is the purpose of a boiler economizer?
A. Reduce water content
B. Recover heat from flue gases
C. Increase pressure
D. Filter impurities
Economizers improve efficiency by using waste heat from flue
gases.
5. What is the function of a steam trap?
A. Generate steam
B. Remove condensate
C. Increase pressure
D. Control temperature
Steam traps remove condensate without losing live steam.
6. What is the primary risk of low water level in a boiler?
A. Reduced efficiency
B. Overheating and potential boiler failure
C. Corrosion
D. Increased fuel consumption
Low water exposes boiler surfaces, causing overheating and
possible rupture.
7. What is the function of a centrifugal pump in a boiler system?
A. Compress steam
B. Heat water
C. Move water or condensate
D. Measure pressure
Centrifugal pumps are used to circulate water in boiler systems.
, 8. Which gauge indicates boiler water level?
A. Pressure gauge
B. Thermometer
C. Sight glass
D. Flow meter
Sight glasses provide a visual indicator of water level.
9. What is the typical operating pressure range for low-pressure
steam boilers?
A. 0–5 psi
B. 15–30 psi
C. 50–100 psi
D. 150–200 psi
Low-pressure steam boilers operate at pressures up to around 30
psi.
10. What is the effect of scale formation inside a boiler?
A. Increase efficiency
B. Reduce heat transfer and cause overheating
C. Improve water circulation
D. Lower fuel consumption
Scale acts as an insulator, reducing heat transfer and causing hot
spots.
11. Which type of valve is used to control water flow to a boiler?
A. Check valve
B. Pressure relief valve
C. Gate valve
D. Steam trap
Gate valves are commonly used to start or stop flow to the boiler.
12. Which device prevents backflow in a boiler feed system?
A. Safety valve
Practice Questions With Correct Answers
(Verified Answers) Plus Rationales
1. What is the main purpose of a boiler’s safety valve?
A. To control fuel supply
B. To release excess pressure
C. To monitor water level
D. To regulate temperature
Safety valves prevent boilers from exceeding maximum pressure,
avoiding explosions.
2. What type of fuel is most commonly used in large industrial
boilers?
A. Coal
B. Natural gas
C. Wood
D. Diesel
Natural gas is preferred for its efficiency and cleaner combustion.
3. What does a deaerator remove from boiler feedwater?
A. Solids
B. Dissolved gases
C. Oil
D. Bacteria
, Dissolved oxygen and carbon dioxide are removed to prevent
corrosion.
4. What is the purpose of a boiler economizer?
A. Reduce water content
B. Recover heat from flue gases
C. Increase pressure
D. Filter impurities
Economizers improve efficiency by using waste heat from flue
gases.
5. What is the function of a steam trap?
A. Generate steam
B. Remove condensate
C. Increase pressure
D. Control temperature
Steam traps remove condensate without losing live steam.
6. What is the primary risk of low water level in a boiler?
A. Reduced efficiency
B. Overheating and potential boiler failure
C. Corrosion
D. Increased fuel consumption
Low water exposes boiler surfaces, causing overheating and
possible rupture.
7. What is the function of a centrifugal pump in a boiler system?
A. Compress steam
B. Heat water
C. Move water or condensate
D. Measure pressure
Centrifugal pumps are used to circulate water in boiler systems.
, 8. Which gauge indicates boiler water level?
A. Pressure gauge
B. Thermometer
C. Sight glass
D. Flow meter
Sight glasses provide a visual indicator of water level.
9. What is the typical operating pressure range for low-pressure
steam boilers?
A. 0–5 psi
B. 15–30 psi
C. 50–100 psi
D. 150–200 psi
Low-pressure steam boilers operate at pressures up to around 30
psi.
10. What is the effect of scale formation inside a boiler?
A. Increase efficiency
B. Reduce heat transfer and cause overheating
C. Improve water circulation
D. Lower fuel consumption
Scale acts as an insulator, reducing heat transfer and causing hot
spots.
11. Which type of valve is used to control water flow to a boiler?
A. Check valve
B. Pressure relief valve
C. Gate valve
D. Steam trap
Gate valves are commonly used to start or stop flow to the boiler.
12. Which device prevents backflow in a boiler feed system?
A. Safety valve
