Power Engineer Fourth Class Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1.A boiler operator observes that the pressure inside a closed steam boiler is
increasing while the burner continues firing. Which device is designed to
prevent excessive pressure from developing?
A. Feedwater regulator
B. Safety valve
C. Blowdown valve
D. Pressure gauge
Correct Answer: B. Safety valve
The safety valve is a protective device that automatically releases steam
when boiler pressure exceeds a predetermined safe limit, preventing
catastrophic failure.
2. The primary purpose of a boiler water treatment program is to:
A. Increase fuel consumption
B. Prevent scale and corrosion formation
C. Increase steam temperature above design limits
D. Reduce boiler pressure
Correct Answer: B. Prevent scale and corrosion formation
,Proper water treatment removes impurities and controls chemical
conditions to minimize deposits, corrosion, and operational problems
inside the boiler system.
3. In a steam boiler, the function of the feedwater system is to:
A. Remove steam from the turbine
B. Supply treated water to replace converted steam
C. Increase combustion temperature
D. Reduce exhaust pressure
Correct Answer: B. Supply treated water to replace converted steam
The feedwater system continuously supplies properly conditioned water to
the boiler to maintain water level and steam production.
4. The boiling point of water increases when:
A. Atmospheric pressure decreases
B. Pressure increases
C. Temperature decreases
D. Water volume decreases
Correct Answer: B. Pressure increases
Increasing pressure raises the temperature required for water to change
from liquid to steam because the molecules require more energy to escape.
5. The main purpose of a boiler gauge glass is to:
A. Measure steam temperature
B. Show the water level inside the boiler
C. Control fuel pressure
D. Measure combustion efficiency
Correct Answer: B. Show the water level inside the boiler
,The gauge glass provides a direct visual indication of the boiler water level,
helping operators maintain safe operating conditions.
6. A boiler low-water condition is dangerous because it can:
A. Reduce steam pressure only
B. Cause overheating of boiler heating surfaces
C. Increase water treatment efficiency
D. Improve combustion
Correct Answer: B. Cause overheating of boiler heating surfaces
When water level becomes too low, metal surfaces may lose cooling and
become overheated, potentially causing severe boiler damage.
7. The purpose of a boiler blowdown operation is to:
A. Add chemicals into the boiler
B. Remove concentrated impurities from boiler water
C. Increase combustion air supply
D. Increase steam temperature
Correct Answer: B. Remove concentrated impurities from boiler water
Blowdown removes dissolved solids and contaminants that accumulate as
water is converted into steam.
8. The unit of pressure commonly used in boiler operations is:
A. Celsius
B. Kilowatt
C. Pascal or psi
D. Joule
Correct Answer: C. Pascal or psi
Pressure is measured as force applied over an area, commonly expressed in
pascals in SI units or pounds per square inch in imperial units.
, 9. The primary function of a burner in a boiler is to:
A. Remove dissolved gases
B. Convert chemical energy into heat energy
C. Control steam flow
D. Reduce pressure
Correct Answer: B. Convert chemical energy into heat energy
A burner mixes fuel and air to produce combustion, releasing heat that
transfers to boiler water.
10. The term “latent heat of vaporization” refers to:
A. Heat required to change liquid into vapor without temperature change
B. Heat lost from insulation
C. Heat used to increase temperature only
D. Heat produced by combustion
Correct Answer: A. Heat required to change liquid into vapor without
temperature change
Latent heat is energy absorbed during a phase change while the substance
remains at the same temperature.
11. The purpose of insulation on steam piping is to:
A. Increase heat loss
B. Reduce heat transfer to the surroundings
C. Increase pipe corrosion
D. Reduce steam pressure
Correct Answer: B. Reduce heat transfer to the surroundings
Insulation minimizes energy losses, improves efficiency, and protects
personnel from hot surfaces.
12. A centrifugal pump operates by converting:
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1.A boiler operator observes that the pressure inside a closed steam boiler is
increasing while the burner continues firing. Which device is designed to
prevent excessive pressure from developing?
A. Feedwater regulator
B. Safety valve
C. Blowdown valve
D. Pressure gauge
Correct Answer: B. Safety valve
The safety valve is a protective device that automatically releases steam
when boiler pressure exceeds a predetermined safe limit, preventing
catastrophic failure.
2. The primary purpose of a boiler water treatment program is to:
A. Increase fuel consumption
B. Prevent scale and corrosion formation
C. Increase steam temperature above design limits
D. Reduce boiler pressure
Correct Answer: B. Prevent scale and corrosion formation
,Proper water treatment removes impurities and controls chemical
conditions to minimize deposits, corrosion, and operational problems
inside the boiler system.
3. In a steam boiler, the function of the feedwater system is to:
A. Remove steam from the turbine
B. Supply treated water to replace converted steam
C. Increase combustion temperature
D. Reduce exhaust pressure
Correct Answer: B. Supply treated water to replace converted steam
The feedwater system continuously supplies properly conditioned water to
the boiler to maintain water level and steam production.
4. The boiling point of water increases when:
A. Atmospheric pressure decreases
B. Pressure increases
C. Temperature decreases
D. Water volume decreases
Correct Answer: B. Pressure increases
Increasing pressure raises the temperature required for water to change
from liquid to steam because the molecules require more energy to escape.
5. The main purpose of a boiler gauge glass is to:
A. Measure steam temperature
B. Show the water level inside the boiler
C. Control fuel pressure
D. Measure combustion efficiency
Correct Answer: B. Show the water level inside the boiler
,The gauge glass provides a direct visual indication of the boiler water level,
helping operators maintain safe operating conditions.
6. A boiler low-water condition is dangerous because it can:
A. Reduce steam pressure only
B. Cause overheating of boiler heating surfaces
C. Increase water treatment efficiency
D. Improve combustion
Correct Answer: B. Cause overheating of boiler heating surfaces
When water level becomes too low, metal surfaces may lose cooling and
become overheated, potentially causing severe boiler damage.
7. The purpose of a boiler blowdown operation is to:
A. Add chemicals into the boiler
B. Remove concentrated impurities from boiler water
C. Increase combustion air supply
D. Increase steam temperature
Correct Answer: B. Remove concentrated impurities from boiler water
Blowdown removes dissolved solids and contaminants that accumulate as
water is converted into steam.
8. The unit of pressure commonly used in boiler operations is:
A. Celsius
B. Kilowatt
C. Pascal or psi
D. Joule
Correct Answer: C. Pascal or psi
Pressure is measured as force applied over an area, commonly expressed in
pascals in SI units or pounds per square inch in imperial units.
, 9. The primary function of a burner in a boiler is to:
A. Remove dissolved gases
B. Convert chemical energy into heat energy
C. Control steam flow
D. Reduce pressure
Correct Answer: B. Convert chemical energy into heat energy
A burner mixes fuel and air to produce combustion, releasing heat that
transfers to boiler water.
10. The term “latent heat of vaporization” refers to:
A. Heat required to change liquid into vapor without temperature change
B. Heat lost from insulation
C. Heat used to increase temperature only
D. Heat produced by combustion
Correct Answer: A. Heat required to change liquid into vapor without
temperature change
Latent heat is energy absorbed during a phase change while the substance
remains at the same temperature.
11. The purpose of insulation on steam piping is to:
A. Increase heat loss
B. Reduce heat transfer to the surroundings
C. Increase pipe corrosion
D. Reduce steam pressure
Correct Answer: B. Reduce heat transfer to the surroundings
Insulation minimizes energy losses, improves efficiency, and protects
personnel from hot surfaces.
12. A centrifugal pump operates by converting:
