Maryland Stationary Engineer Grade 4 License Exam Prep 2026: Entry-Level Study Guide with 200+ Practice Questions, Detailed Explanations, 30–99 HP Operation, Boiler Safety Fundamentals, COMAR 09.17, and PSI Exam Tips – Start Your Stationary Engineerin

Maryland Stationary Engineer Grade 4 License Exam Prep 2026:
Entry-Level Study Guide with 200+ Practice Questions, Detailed
Explanations, 30–99 HP Operation, Boiler Safety Fundamentals,
COMAR 09.17, and PSI Exam Tips – Start Your Stationary
Engineering Career

1. What is the maximum horsepower (HP) a Grade 4 stationary engineer is authorized to
operate in Maryland?

 A) 15 – 29 HP
 B) 30 – 99 HP
 C) 100 – 299 HP
 D) 300 – 499 HP

Explanation: A Grade 4 license authorizes operation of boilers and equipment in the range
of 30 to 99 horsepower. Grade 3 is required for 100 HP and above.

2. What is the minimum experience required to qualify for the Grade 4 examination via the
progressive pathway?

 A) No experience required
 B) 6 months as a Grade 5 engineer
 C) 1 year as a Grade 5 engineer
 D) 2 years as a Grade 5 engineer

Explanation: The standard progressive pathway requires 6 months of documented
experience as a Grade 5 stationary engineer.

3. What alternative qualification can be used instead of 6 months of Grade 5 experience?

 A) High school diploma
 B) 3 credit hours or CEUs in boiler operations
 C) Valid driver's license
 D) First aid certification

Explanation: Completion of 3 credit hours or continuing education units (CEUs) in
boiler safety or operations qualifies for the Grade 4 examination.

, 4. What is the first thing you should check before starting a boiler?

 A) Fuel pressure
 B) Water level in the gauge glass
 C) Steam pressure
 D) Stack temperature

Explanation: Before any startup, the operator must confirm that the boiler has a safe water
level to prevent overheating and tube damage.

5. What is the purpose of a low-water fuel cutoff?

 A) Reduce fuel pressure
 B) Shut off fuel supply when water level drops below safe limits
 C) Increase feedwater flow
 D) Control steam pressure

Explanation: A low-water fuel cutoff is a critical safety device that interrupts the fuel supply
if water level falls to a dangerous point.

6. What is the function of a safety valve on a boiler?

 A) Control steam temperature
 B) Relieve pressure if maximum allowable working pressure is exceeded
 C) Regulate fuel flow
 D) Monitor water chemistry

Explanation: The safety valve automatically opens at the set pressure to prevent
overpressure and potential explosion.

7. How often should gauge glasses be blown down?

 A) Weekly
 B) At least once per shift or daily
 C) Monthly
 D) Annually

Explanation: Blowing down gauge glasses daily confirms that water passages are clear
and the water level indication is accurate.

8. What is the purpose of a try lever on a safety valve?

,  A) Adjust pressure setting
 B) Manually test the valve operation
 C) Lock the valve closed
 D) Increase valve capacity

Explanation: The try lever allows manual testing of the safety valve to ensure it is not stuck
and will open freely when required.

9. What does a gauge glass indicate?

 A) Steam pressure
 B) Water level in the boiler
 C) Fuel flow
 D) Flue gas temperature

Explanation: The gauge glass provides a direct visual indication of the water level,
essential for safe boiler operation.

10. What is the purpose of a steam pressure gauge?

 A) Measure water level
 B) Measure steam pressure inside the boiler
 C) Measure fuel flow
 D) Measure stack temperature

Explanation: The pressure gauge indicates the operating pressure of the boiler.

11. What is the minimum required purging time for a boiler before ignition?

 A) No purge required
 B) Sufficient time to complete multiple air changes (typically 5–10)
 C) 10 seconds
 D) 30 seconds

Explanation: Proper purging removes combustible gases from the furnace. Follow
manufacturer specifications for purge timing.

12. What is the purpose of a steam trap?

 A) Trap steam in the system
 B) Remove condensate and non-condensable gases while retaining steam