ABSA 4B – Fourth Class Power Engineering
Part B Examination Questions and Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary function of a deaerator in a boiler system?
A. To increase steam pressure
B. To remove dissolved gases from feedwater
C. To cool condensate before return
D. To increase boiler water alkalinity
Answer: B
Rationale: A deaerator removes dissolved oxygen and carbon dioxide
from boiler feedwater. These gases can cause corrosion in boilers,
piping, and other system components. By heating and mechanically
separating gases from water, the deaerator protects the system from
corrosion damage.
, 2. In a boiler system, scale formation on heat transfer surfaces will
primarily cause:
A. Increased heat transfer efficiency
B. Reduced fuel consumption
C. Decreased heat transfer efficiency
D. Increased condensate return
Answer: C
Rationale: Scale acts as an insulating layer on heat transfer surfaces.
This reduces the efficiency of heat transfer from the flame or hot gases
to the water, requiring more fuel to produce the same amount of
steam.
3. What device is commonly used to measure the water level in a
boiler?
A. Pressure gauge
B. Gauge glass
C. Thermocouple
D. Manometer
Answer: B
,Rationale: The gauge glass, also known as a sight glass, provides a
direct visual indication of the water level inside the boiler. Maintaining
proper water level is critical for safe boiler operation.
4. The main purpose of a boiler blowdown is to:
A. Increase boiler pressure
B. Remove suspended and dissolved solids
C. Reduce steam temperature
D. Improve combustion efficiency
Answer: B
Rationale: Blowdown removes accumulated impurities, dissolved
solids, and sludge from the boiler water. This prevents scale
formation, foaming, and carryover, helping maintain water quality
and safe operation.
5. A safety valve on a boiler is designed to:
A. Regulate steam pressure during operation
B. Automatically relieve excess pressure
C. Increase steam production
D. Control feedwater flow
, Answer: B
Rationale: Safety valves automatically release steam when the
pressure exceeds a predetermined set point. This prevents dangerous
overpressure conditions that could lead to boiler failure or explosion.
6. In a steam trap, the main purpose is to:
A. Remove steam from the system
B. Remove condensate while retaining steam
C. Increase pressure in the line
D. Regulate temperature
Answer: B
Rationale: Steam traps remove condensate and non-condensable
gases while preventing the loss of live steam. This ensures efficient
heat transfer and prevents water hammer.
7. What condition is most likely to cause water hammer in steam
piping?
A. Excessive steam pressure
B. Condensate accumulation in piping
Part B Examination Questions and Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary function of a deaerator in a boiler system?
A. To increase steam pressure
B. To remove dissolved gases from feedwater
C. To cool condensate before return
D. To increase boiler water alkalinity
Answer: B
Rationale: A deaerator removes dissolved oxygen and carbon dioxide
from boiler feedwater. These gases can cause corrosion in boilers,
piping, and other system components. By heating and mechanically
separating gases from water, the deaerator protects the system from
corrosion damage.
, 2. In a boiler system, scale formation on heat transfer surfaces will
primarily cause:
A. Increased heat transfer efficiency
B. Reduced fuel consumption
C. Decreased heat transfer efficiency
D. Increased condensate return
Answer: C
Rationale: Scale acts as an insulating layer on heat transfer surfaces.
This reduces the efficiency of heat transfer from the flame or hot gases
to the water, requiring more fuel to produce the same amount of
steam.
3. What device is commonly used to measure the water level in a
boiler?
A. Pressure gauge
B. Gauge glass
C. Thermocouple
D. Manometer
Answer: B
,Rationale: The gauge glass, also known as a sight glass, provides a
direct visual indication of the water level inside the boiler. Maintaining
proper water level is critical for safe boiler operation.
4. The main purpose of a boiler blowdown is to:
A. Increase boiler pressure
B. Remove suspended and dissolved solids
C. Reduce steam temperature
D. Improve combustion efficiency
Answer: B
Rationale: Blowdown removes accumulated impurities, dissolved
solids, and sludge from the boiler water. This prevents scale
formation, foaming, and carryover, helping maintain water quality
and safe operation.
5. A safety valve on a boiler is designed to:
A. Regulate steam pressure during operation
B. Automatically relieve excess pressure
C. Increase steam production
D. Control feedwater flow
, Answer: B
Rationale: Safety valves automatically release steam when the
pressure exceeds a predetermined set point. This prevents dangerous
overpressure conditions that could lead to boiler failure or explosion.
6. In a steam trap, the main purpose is to:
A. Remove steam from the system
B. Remove condensate while retaining steam
C. Increase pressure in the line
D. Regulate temperature
Answer: B
Rationale: Steam traps remove condensate and non-condensable
gases while preventing the loss of live steam. This ensures efficient
heat transfer and prevents water hammer.
7. What condition is most likely to cause water hammer in steam
piping?
A. Excessive steam pressure
B. Condensate accumulation in piping
