Louisiana (New Orleans) Second Class Stationary Boilers
661-LA 661 Exam ACTUAL EXAM COMPLETE QUESTIONS
AND CORRECT ANSWERS LATEST UPDATED 2026
INTRODUCTION
Preparing for the Louisiana (New Orleans) Second Class Stationary
Boilers 661-LA Exam requires a rigorous understanding of high-pressure
steam plant operations, thermodynamics, water chemistry, and municipal
safety codes. This complete study resource features verified multiple-
choice questions complete with bold-italicized answers and in-depth
explanations designed to ensure absolute mastery of the material.
1. What is the primary purpose of a low-water fuel cutoff (LWCO) on a
steam boiler?
A) To maintain the correct steam pressure
B) To shut off the burner when the water level drops below a safe
operating point
C) To regulate the feedwater pump speed
D) To drain excess water from the boiler drum
Answer: B) To shut off the burner when the water level drops below
a safe operating point
Explanation: The low-water fuel cutoff is a critical safety device
,designed to immediately interrupt the fuel supply to the burner if
the water level falls below the lowest safe visible water line in the
gauge glass, preventing catastrophic overheating and vessel failure.
2. When blowing down a steam boiler with a combination of quick-
opening and slow-opening valves, which valve is opened first?
A) The slow-opening valve
B) The quick-opening valve
C) Both valves must be opened simultaneously
D) The sequence does not matter
Answer: B) The quick-opening valve
Explanation: The quick-opening valve (nearest the boiler) is always
opened first and closed last to take the brunt of the wear and high-
velocity abrasive scaling, protecting the downstream slow-opening
valve which acts as the primary sealing mechanism.
3. What condition is caused by oil or organic contamination in boiler
water?
A) Caustic embrittlement
B) Priming and foaming
C) Scale formation
D) Oxygen pitting
Answer: B) Priming and foaming
Explanation: Oil, grease, and high concentrations of suspended solids
lower the surface tension of the water in the steam drum, leading to
,unstable bubbling (foaming) and the violent projection of water slugs
into the steam lines (priming).
4. Why is a block valve strictly prohibited between the boiler shell and
its safety valve?
A) It increases the operating pressure drop
B) It can be accidentally closed, isolating the safety valve and
risking an overpressure explosion
C) It interferes with regular water level testing
D) It causes turbulence in the steam header
Answer: B) It can be accidentally closed, isolating the safety valve
and risking an overpressure explosion
Explanation: ASME codes explicitly forbid any type of shutoff or block
valve between the pressure vessel and the safety relief valve to
ensure that overpressure protection remains permanently and
unconditionally functional.
5. What is the primary function of a deaerator in a boiler feedwater
system?
A) To increase the temperature of the makeup water
B) To remove dissolved gases such as oxygen and carbon dioxide
C) To precipitate out dissolved calcium and magnesium
D) To adjust the pH level of the incoming water supply
Answer: B) To remove dissolved gases such as oxygen and carbon
dioxide
Explanation: Dissolved oxygen and carbon dioxide cause severe
, pitting and corrosive attack on metal surfaces within the boiler
tubes and piping. A deaerator mechanically heats the feedwater to
its saturation point to strip out these non-condensable gases.
6. What term describes the carryover of water droplets and impurities
into the steam header due to high water levels or surging?
A) Thermal shock
B) Carryover
C) Condensation
D) Stratification
Answer: B) Carryover
Explanation: Carryover is the general term for the undesirable-
carrying of moisture, solid salts, and suspended matter out of the
boiler and into the steam piping system, often caused by high boiler
water level or sudden steam demand.
7. How frequently should the low-water fuel cutoff be tested by
blowing down the float chamber during normal operation?
A) Once a year
B) Once a month
C) Daily or per shift
D) Weekly
Answer: C) Daily or per shift
Explanation: Standard operational safety protocols require daily or
per-shift blowdown of the LWCO float chamber to flush out
661-LA 661 Exam ACTUAL EXAM COMPLETE QUESTIONS
AND CORRECT ANSWERS LATEST UPDATED 2026
INTRODUCTION
Preparing for the Louisiana (New Orleans) Second Class Stationary
Boilers 661-LA Exam requires a rigorous understanding of high-pressure
steam plant operations, thermodynamics, water chemistry, and municipal
safety codes. This complete study resource features verified multiple-
choice questions complete with bold-italicized answers and in-depth
explanations designed to ensure absolute mastery of the material.
1. What is the primary purpose of a low-water fuel cutoff (LWCO) on a
steam boiler?
A) To maintain the correct steam pressure
B) To shut off the burner when the water level drops below a safe
operating point
C) To regulate the feedwater pump speed
D) To drain excess water from the boiler drum
Answer: B) To shut off the burner when the water level drops below
a safe operating point
Explanation: The low-water fuel cutoff is a critical safety device
,designed to immediately interrupt the fuel supply to the burner if
the water level falls below the lowest safe visible water line in the
gauge glass, preventing catastrophic overheating and vessel failure.
2. When blowing down a steam boiler with a combination of quick-
opening and slow-opening valves, which valve is opened first?
A) The slow-opening valve
B) The quick-opening valve
C) Both valves must be opened simultaneously
D) The sequence does not matter
Answer: B) The quick-opening valve
Explanation: The quick-opening valve (nearest the boiler) is always
opened first and closed last to take the brunt of the wear and high-
velocity abrasive scaling, protecting the downstream slow-opening
valve which acts as the primary sealing mechanism.
3. What condition is caused by oil or organic contamination in boiler
water?
A) Caustic embrittlement
B) Priming and foaming
C) Scale formation
D) Oxygen pitting
Answer: B) Priming and foaming
Explanation: Oil, grease, and high concentrations of suspended solids
lower the surface tension of the water in the steam drum, leading to
,unstable bubbling (foaming) and the violent projection of water slugs
into the steam lines (priming).
4. Why is a block valve strictly prohibited between the boiler shell and
its safety valve?
A) It increases the operating pressure drop
B) It can be accidentally closed, isolating the safety valve and
risking an overpressure explosion
C) It interferes with regular water level testing
D) It causes turbulence in the steam header
Answer: B) It can be accidentally closed, isolating the safety valve
and risking an overpressure explosion
Explanation: ASME codes explicitly forbid any type of shutoff or block
valve between the pressure vessel and the safety relief valve to
ensure that overpressure protection remains permanently and
unconditionally functional.
5. What is the primary function of a deaerator in a boiler feedwater
system?
A) To increase the temperature of the makeup water
B) To remove dissolved gases such as oxygen and carbon dioxide
C) To precipitate out dissolved calcium and magnesium
D) To adjust the pH level of the incoming water supply
Answer: B) To remove dissolved gases such as oxygen and carbon
dioxide
Explanation: Dissolved oxygen and carbon dioxide cause severe
, pitting and corrosive attack on metal surfaces within the boiler
tubes and piping. A deaerator mechanically heats the feedwater to
its saturation point to strip out these non-condensable gases.
6. What term describes the carryover of water droplets and impurities
into the steam header due to high water levels or surging?
A) Thermal shock
B) Carryover
C) Condensation
D) Stratification
Answer: B) Carryover
Explanation: Carryover is the general term for the undesirable-
carrying of moisture, solid salts, and suspended matter out of the
boiler and into the steam piping system, often caused by high boiler
water level or sudden steam demand.
7. How frequently should the low-water fuel cutoff be tested by
blowing down the float chamber during normal operation?
A) Once a year
B) Once a month
C) Daily or per shift
D) Weekly
Answer: C) Daily or per shift
Explanation: Standard operational safety protocols require daily or
per-shift blowdown of the LWCO float chamber to flush out
