3rd Class Power Engineer B2 Exam Questions
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which type of feedwater heater uses extracted steam that mixes
directly with feedwater?
A. Closed feedwater heater
B. Surface condenser
C. Open feedwater heater (deaerator)
D. Economizer
Rationale: An open feedwater heater, commonly called a deaerator,
mixes extraction steam directly with feedwater. This raises feedwater
temperature while removing dissolved oxygen and carbon dioxide,
improving boiler efficiency and reducing corrosion.
2. The primary purpose of a deaerator is to:
A. Increase boiler pressure
B. Remove suspended solids
,C. Remove dissolved oxygen and carbon dioxide
D. Reduce steam temperature
Rationale: Deaerators eliminate dissolved gases that cause corrosion
in boilers and condensate systems. Oxygen promotes pitting, while
carbon dioxide forms carbonic acid that attacks piping.
3. What is the primary function of a steam separator?
A. Lower steam pressure
B. Increase steam velocity
C. Remove entrained moisture from steam
D. Increase condensate flow
Rationale: Steam separators remove water droplets from steam,
ensuring dry steam reaches turbines and process equipment. Dry
steam improves efficiency and minimizes erosion.
4. Boiler feed pumps are typically designed to produce pressure that
is:
A. Equal to boiler pressure
B. Less than boiler pressure
,C. Higher than boiler pressure
D. Independent of boiler pressure
Rationale: Feedwater must overcome boiler pressure before entering
the boiler. Therefore, feed pumps always develop a discharge pressure
greater than boiler operating pressure.
5. Which valve prevents reverse flow from a boiler into the
feedwater system?
A. Globe valve
B. Gate valve
C. Pressure relief valve
D. Check valve
Rationale: Check valves automatically prevent reverse flow, protecting
feedwater equipment and maintaining safe operation during pump
shutdown or pressure fluctuations.
6. Cavitation in a centrifugal pump is caused primarily by:
A. High discharge pressure
B. Low motor voltage
, C. Insufficient suction pressure causing vapor formation
D. Excessive lubrication
Rationale: Cavitation occurs when pressure at the pump inlet falls
below the liquid's vapor pressure. Vapor bubbles form and collapse
violently, damaging impellers and reducing pump performance.
7. The Net Positive Suction Head (NPSH) is important because it:
A. Increases discharge pressure
B. Controls motor speed
C. Prevents cavitation
D. Measures pump efficiency
Rationale: Adequate NPSH ensures sufficient pressure at the pump
inlet to prevent vaporization of the liquid and subsequent cavitation.
8. A centrifugal pump converts:
A. Heat into pressure
B. Pressure into velocity only
C. Mechanical energy into hydraulic energy
D. Hydraulic energy into electrical energy
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which type of feedwater heater uses extracted steam that mixes
directly with feedwater?
A. Closed feedwater heater
B. Surface condenser
C. Open feedwater heater (deaerator)
D. Economizer
Rationale: An open feedwater heater, commonly called a deaerator,
mixes extraction steam directly with feedwater. This raises feedwater
temperature while removing dissolved oxygen and carbon dioxide,
improving boiler efficiency and reducing corrosion.
2. The primary purpose of a deaerator is to:
A. Increase boiler pressure
B. Remove suspended solids
,C. Remove dissolved oxygen and carbon dioxide
D. Reduce steam temperature
Rationale: Deaerators eliminate dissolved gases that cause corrosion
in boilers and condensate systems. Oxygen promotes pitting, while
carbon dioxide forms carbonic acid that attacks piping.
3. What is the primary function of a steam separator?
A. Lower steam pressure
B. Increase steam velocity
C. Remove entrained moisture from steam
D. Increase condensate flow
Rationale: Steam separators remove water droplets from steam,
ensuring dry steam reaches turbines and process equipment. Dry
steam improves efficiency and minimizes erosion.
4. Boiler feed pumps are typically designed to produce pressure that
is:
A. Equal to boiler pressure
B. Less than boiler pressure
,C. Higher than boiler pressure
D. Independent of boiler pressure
Rationale: Feedwater must overcome boiler pressure before entering
the boiler. Therefore, feed pumps always develop a discharge pressure
greater than boiler operating pressure.
5. Which valve prevents reverse flow from a boiler into the
feedwater system?
A. Globe valve
B. Gate valve
C. Pressure relief valve
D. Check valve
Rationale: Check valves automatically prevent reverse flow, protecting
feedwater equipment and maintaining safe operation during pump
shutdown or pressure fluctuations.
6. Cavitation in a centrifugal pump is caused primarily by:
A. High discharge pressure
B. Low motor voltage
, C. Insufficient suction pressure causing vapor formation
D. Excessive lubrication
Rationale: Cavitation occurs when pressure at the pump inlet falls
below the liquid's vapor pressure. Vapor bubbles form and collapse
violently, damaging impellers and reducing pump performance.
7. The Net Positive Suction Head (NPSH) is important because it:
A. Increases discharge pressure
B. Controls motor speed
C. Prevents cavitation
D. Measures pump efficiency
Rationale: Adequate NPSH ensures sufficient pressure at the pump
inlet to prevent vaporization of the liquid and subsequent cavitation.
8. A centrifugal pump converts:
A. Heat into pressure
B. Pressure into velocity only
C. Mechanical energy into hydraulic energy
D. Hydraulic energy into electrical energy
