Exam 100 Practice Questions And

2nd Class Stationary Engineer License Exam 100 Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

Q1. What is the primary purpose of a steam boiler in an industrial plant?

• To store heat
• To increase water temperature slightly
• To convert water into steam for process and power
• To reduce plant emissions

Rationale: Steam boilers’ main function is to generate steam for heating,

process, or power applications.

Q2. What device maintains the water level inside a boiler automatically?

• Pressure switch
• Feedwater regulator 1 / 4

• Blowdown valve
• Gauge glass

Rationale: The feedwater regulator adjusts water flow to maintain proper

boiler level.

Q3. What is the primary function of a boiler safety valve?

• Indicate steam pressure
• Prevent boiler overpressure
• Regulate water level
• Reduce stack temperature

Rationale: Safety valves protect the boiler shell from dangerous pressure

levels.

Q4. What is the minimum number of gauge glasses required on a boiler operating above 400 psi?

• One
• Two
• Three
• Four

Rationale: High-pressure boilers require two gauge glasses for redundancy.

Q5. Which fuel provides the highest heating value per pound? 2 / 4

• Wood
• Bituminous coal
• Lignite
• Fuel oil

Rationale: Fuel oil contains more BTU per pound compared to other listed

fuels.

Q6. What is the main purpose of boiler blowdown?

• Increase steam temperature
• Reduce boiler pressure
• Remove dissolved solids and sludge
• Remove scale from tubes

Rationale: Blowdown prevents concentration of impurities that cause scale

and corrosion.

Q7. What is the term for heat added to steam without increasing its pressure?

• Latent heat
• Superheat
• Sensible heat
• Enthalpy

Rationale: Superheating raises temperature at constant pressure. 3 / 4

Q8. What is the main function of the economizer?

• Store hot water
• Increase boiler pressure
• Recover waste heat from flue gases
• Remove moisture from steam

Rationale: Economizers use flue-gas heat to warm feedwater, improving

efficiency.

Q9. What device reduces steam pressure in a distribution system?

• Check valve
• Relief valve
• Safety valve
• Pressure-reducing valve

Rationale: PRVs regulate downstream pressure for process and heating

systems.

Q10. What is the color of a proper natural-gas flame in a boiler?

• Red
• Yellow
• Blue
• / 4