1st Class Power Engineer B3 Exam Questions
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a deaerator in a boiler plant?
A. To increase boiler pressure
B. To remove dissolved oxygen and carbon dioxide from feedwater
C. To increase steam temperature
D. To reduce boiler blowdown
Correct Answer: B. To remove dissolved oxygen and carbon dioxide
from feedwater
Rationale: A deaerator removes dissolved gases, primarily oxygen and
carbon dioxide, from boiler feedwater. These gases contribute
significantly to corrosion within boilers, piping, and condensate
systems. By heating the feedwater and venting dissolved gases, the
deaerator helps extend equipment life, improve efficiency, and reduce
maintenance costs.
, 2. Which boiler component separates steam from water before
steam leaves the drum?
A. Economizer
B. Steam separator
C. Mud drum
D. Air preheater
Correct Answer: B. Steam separator
Rationale: Steam separators remove entrained water droplets from
saturated steam before it exits the steam drum. Dry steam improves
turbine efficiency, reduces erosion, and prevents water hammer in
downstream piping.
3. The purpose of an economizer is to:
A. Increase condensate pressure
B. Recover waste heat to preheat feedwater
C. Superheat steam
D. Cool flue gases below ambient temperature
Correct Answer: B. Recover waste heat to preheat feedwater
Rationale: An economizer uses residual heat from boiler flue gases to
preheat incoming feedwater. This reduces fuel consumption, improves
,boiler efficiency, and lowers stack temperatures while recovering
energy that would otherwise be lost.
4. What is the normal function of a safety valve?
A. Maintain water level
B. Prevent excessive boiler pressure
C. Increase steam flow
D. Remove impurities
Correct Answer: B. Prevent excessive boiler pressure
Rationale: Safety valves automatically open when boiler pressure
exceeds a predetermined setpoint, preventing dangerous overpressure
conditions that could lead to catastrophic boiler failure.
5. Boiler blowdown primarily removes:
A. Steam bubbles
B. Dissolved and suspended solids
C. Oxygen only
D. Fuel residue
Correct Answer: B. Dissolved and suspended solids
, Rationale: Blowdown controls the concentration of dissolved solids,
sludge, and contaminants that accumulate during steam generation.
Proper blowdown minimizes scale formation, corrosion, and carryover
while maintaining water chemistry.
6. What instrument measures boiler drum water level?
A. Bourdon gauge
B. Sight glass (gauge glass)
C. Thermocouple
D. Venturi meter
Correct Answer: B. Sight glass (gauge glass)
Rationale: The gauge glass provides operators with a direct visual
indication of boiler water level. It serves as a primary safety device
and is routinely checked to ensure proper boiler operation.
7. Superheated steam differs from saturated steam because it:
A. Contains more water droplets
B. Has a temperature above its saturation temperature at a given
pressure
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a deaerator in a boiler plant?
A. To increase boiler pressure
B. To remove dissolved oxygen and carbon dioxide from feedwater
C. To increase steam temperature
D. To reduce boiler blowdown
Correct Answer: B. To remove dissolved oxygen and carbon dioxide
from feedwater
Rationale: A deaerator removes dissolved gases, primarily oxygen and
carbon dioxide, from boiler feedwater. These gases contribute
significantly to corrosion within boilers, piping, and condensate
systems. By heating the feedwater and venting dissolved gases, the
deaerator helps extend equipment life, improve efficiency, and reduce
maintenance costs.
, 2. Which boiler component separates steam from water before
steam leaves the drum?
A. Economizer
B. Steam separator
C. Mud drum
D. Air preheater
Correct Answer: B. Steam separator
Rationale: Steam separators remove entrained water droplets from
saturated steam before it exits the steam drum. Dry steam improves
turbine efficiency, reduces erosion, and prevents water hammer in
downstream piping.
3. The purpose of an economizer is to:
A. Increase condensate pressure
B. Recover waste heat to preheat feedwater
C. Superheat steam
D. Cool flue gases below ambient temperature
Correct Answer: B. Recover waste heat to preheat feedwater
Rationale: An economizer uses residual heat from boiler flue gases to
preheat incoming feedwater. This reduces fuel consumption, improves
,boiler efficiency, and lowers stack temperatures while recovering
energy that would otherwise be lost.
4. What is the normal function of a safety valve?
A. Maintain water level
B. Prevent excessive boiler pressure
C. Increase steam flow
D. Remove impurities
Correct Answer: B. Prevent excessive boiler pressure
Rationale: Safety valves automatically open when boiler pressure
exceeds a predetermined setpoint, preventing dangerous overpressure
conditions that could lead to catastrophic boiler failure.
5. Boiler blowdown primarily removes:
A. Steam bubbles
B. Dissolved and suspended solids
C. Oxygen only
D. Fuel residue
Correct Answer: B. Dissolved and suspended solids
, Rationale: Blowdown controls the concentration of dissolved solids,
sludge, and contaminants that accumulate during steam generation.
Proper blowdown minimizes scale formation, corrosion, and carryover
while maintaining water chemistry.
6. What instrument measures boiler drum water level?
A. Bourdon gauge
B. Sight glass (gauge glass)
C. Thermocouple
D. Venturi meter
Correct Answer: B. Sight glass (gauge glass)
Rationale: The gauge glass provides operators with a direct visual
indication of boiler water level. It serves as a primary safety device
and is routinely checked to ensure proper boiler operation.
7. Superheated steam differs from saturated steam because it:
A. Contains more water droplets
B. Has a temperature above its saturation temperature at a given
pressure
