FIRST CLASS STEAM LICENSE ACTUAL EXAM NEWEST COMPLETE 100 QUESTIONS AND
CORRECT DETAILED ANSWERS| ALREADY GRADED A+
uestion 1
If a high-pressure boiler is generating 20,000 lb/hr of steam, what is the minimum amount of
feedwater that must be supplied to the boiler to maintain a constant water level?
A) 10,000 lb/hr
B) 15,000 lb/hr
C) 20,000 lb/hr
D) 25,000 lb/hr
E) 40,000 lb/hr
Correct Answer: C) 20,000 lb/hr
Rationale: The principle of mass balance dictates that for a boiler to maintain a steady state
(Normal Operating Water Level), the mass of water entering the boiler must equal the
mass of steam exiting the boiler. Therefore, if 20,000 pounds of steam are produced per
hour, 20,000 pounds of water must be supplied, excluding minor losses for blowdown or
leaks.
Question 2
In a deaerator, how are oxygen and other noncondensable gases physically removed from the
system after being separated from the feedwater?
A) Through a bottom drain
B) Through a vacuum pump only
C) Through the vent to the atmosphere
D) By being dissolved back into the condensate
E) Through the main steam header
Correct Answer: C) through the vent
Rationale: A deaerator works by heating feedwater to the boiling point for its pressure,
which reduces the solubility of gases. As oxygen and carbon dioxide are released from the
water, they accumulate at the top of the vessel and must be constantly bled off to the
atmosphere through a vent. If the vent is closed, the gases will re-entrain into the water,
causing corrosive damage to the boiler internals.
Question 3
Which term best describes an integrated network of measuring instruments and controllers that
coordinate to maintain a specific industrial process?
A) Manual system
B) Control system
C) Mechanical system
D) Expansion system
E) Auxiliary system
Correct Answer: B) control
Rationale: A control system in a steam plant refers to the combination of sensors
(transmitters), logic units (controllers), and final elements (valves or dampers). These
, Page 2
components work in a "loop" to ensure that variables like pressure, temperature, and
water level remain within safe and efficient operating parameters without requiring
constant manual adjustment.
Question 4
How much water is theoretically required to produce exactly one pound of steam?
A) 0.5 lb
B) 1 lb
C) 8.3 lb
D) 1 gallon
E) 2 lbs
Correct Answer: B) 1lb
Rationale: In accordance with the law of conservation of mass, matter is neither created nor
destroyed in a closed or open system. One pound of liquid water, when heated to its boiling
point and provided with the latent heat of vaporization, will transform into exactly one
pound of steam vapor.
Question 5
In a low-pressure gas combustion system, what is the function of the "manual reset" valve?
A) It regulates the pressure of the gas
B) It allows the operator to bypass the pilot
C) It is an electric safety valve that cannot be opened until the gas pilot is proven lit
D) It controls the volume of gas based on steam demand
E) It vents gas to the atmosphere during an overpressure event
Correct Answer: C) manual reset
Rationale: The manual reset valve is a critical safety interlock. It is designed to stay closed
to prevent the flow of main gas into the furnace unless specific safety conditions are met—
the primary condition being that a pilot flame is established and "proven" by a flame
scanner. This prevents a buildup of unburned gas that could lead to a furnace explosion.
Question 6
Which component is specifically used for steam loads that require "dry" steam, such as high-
speed steam turbines?
A) Economizers
B) Deaerators
C) Superheaters
D) Feedwater regulators
E) Surface condensers
Correct Answer: C) superheaters
Rationale: Turbines are extremely sensitive to moisture, which can cause erosion and
mechanical damage to the blades. Superheaters heat the steam to a temperature above its
, Page 3
saturation point, ensuring that no liquid water droplets remain. This results in "dry" steam
and significantly higher thermal efficiency for power generation cycles.
Question 7
In a standard feedwater piping arrangement, why is the stop valve located closest to the boiler
shell?
A) To increase the pressure of the water
B) To allow the check valve to be repaired without draining the boiler
C) To prevent the boiler from overfilling
D) To cool the water before it enters the drum
E) To measure the flow of water
Correct Answer: B) stop
Rationale: By placing a manual stop valve between the boiler and the check valve, the
operator can isolate the boiler pressure. This allows for the maintenance or replacement of
the check valve (which is prone to wear) while the boiler remains under pressure and full of
water, avoiding a costly and time-consuming "dump" and restart.
Question 8
In an operating boiler, if the feedwater supply is lost, approximately how long might it take for
the water level in the gauge glass to drop from half full to completely empty?
A) Several hours
B) 30 to 45 minutes
C) A matter of minutes
D) Less than 10 seconds
E) It will never go empty due to the steam pressure
Correct Answer: C) minutes
Rationale: Modern boilers, especially water-tube designs, have a relatively small water
volume compared to their evaporation rate. If the feedwater pump fails while the boiler is
at high fire, the remaining water is converted to steam very rapidly. This makes the water
level one of the most critical variables for the engineer to monitor constantly.
Question 9
What is the primary operational advantage of installing "duplex strainers" in a fuel oil supply
system?
A) They increase the fuel pressure
B) They heat the oil automatically
C) They permit one strainer to be cleaned while the other remains in service
D) They separate water from the oil using centrifugal force
E) They mix different grades of oil together
Correct Answer: C) permit one strainer to be cleaned while the other is in service
Rationale: Continuous operation is vital in steam plants. A duplex strainer consists of two
strainer baskets and a diverter valve. If one basket becomes clogged with debris, the
, Page 4
operator can switch the flow to the clean basket without shutting down the fuel supply to
the burner, ensuring uninterrupted combustion.
Question 10
When comparing superheated steam to saturated steam at the identical pressure, superheated
steam will always possess more:
A) Volume
B) Moisture
C) Heat energy (Enthalpy)
D) Liquid particles
E) Density
Correct Answer: C) heat energy
Rationale: Superheating is the process of adding "sensible heat" to steam after it has
already absorbed the "latent heat" required to change state. Because the temperature of
superheated steam is higher than the saturation temperature for its pressure, its total
enthalpy (BTU content) is significantly higher, allowing it to do more work.
Question 11
To ensure a positive suction head and prevent cavitation in the feedwater pumps, where is the
deaerator traditionally located?
A) In the basement below the pumps
B) Directly on the floor next to the pumps
C) Above the feedwater pumps
D) On the roof of the building
E) Inside the boiler drum
Correct Answer: C) above the feedwater pumps
Rationale: Feedwater in a deaerator is at or near its boiling point. If the pressure at the
pump suction drops, the water will "flash" into steam, causing cavitation. Elevating the
deaerator provides "Static Head" (pressure due to gravity), which ensures the Net Positive
Suction Head (NPSH) is high enough to keep the water in a liquid state as it enters the
pump.
Question 12
On a high-pressure gas system, the gas pilot line provides fuel through which type of valve to the
pressure regulator?
A) Needle valve
B) Check valve
C) Shutoff valve
D) Blowdown valve
E) Safety valve
Correct Answer: C) shutoff
Rationale: A manual shutoff valve is required on the pilot gas line to allow for the complete
CORRECT DETAILED ANSWERS| ALREADY GRADED A+
uestion 1
If a high-pressure boiler is generating 20,000 lb/hr of steam, what is the minimum amount of
feedwater that must be supplied to the boiler to maintain a constant water level?
A) 10,000 lb/hr
B) 15,000 lb/hr
C) 20,000 lb/hr
D) 25,000 lb/hr
E) 40,000 lb/hr
Correct Answer: C) 20,000 lb/hr
Rationale: The principle of mass balance dictates that for a boiler to maintain a steady state
(Normal Operating Water Level), the mass of water entering the boiler must equal the
mass of steam exiting the boiler. Therefore, if 20,000 pounds of steam are produced per
hour, 20,000 pounds of water must be supplied, excluding minor losses for blowdown or
leaks.
Question 2
In a deaerator, how are oxygen and other noncondensable gases physically removed from the
system after being separated from the feedwater?
A) Through a bottom drain
B) Through a vacuum pump only
C) Through the vent to the atmosphere
D) By being dissolved back into the condensate
E) Through the main steam header
Correct Answer: C) through the vent
Rationale: A deaerator works by heating feedwater to the boiling point for its pressure,
which reduces the solubility of gases. As oxygen and carbon dioxide are released from the
water, they accumulate at the top of the vessel and must be constantly bled off to the
atmosphere through a vent. If the vent is closed, the gases will re-entrain into the water,
causing corrosive damage to the boiler internals.
Question 3
Which term best describes an integrated network of measuring instruments and controllers that
coordinate to maintain a specific industrial process?
A) Manual system
B) Control system
C) Mechanical system
D) Expansion system
E) Auxiliary system
Correct Answer: B) control
Rationale: A control system in a steam plant refers to the combination of sensors
(transmitters), logic units (controllers), and final elements (valves or dampers). These
, Page 2
components work in a "loop" to ensure that variables like pressure, temperature, and
water level remain within safe and efficient operating parameters without requiring
constant manual adjustment.
Question 4
How much water is theoretically required to produce exactly one pound of steam?
A) 0.5 lb
B) 1 lb
C) 8.3 lb
D) 1 gallon
E) 2 lbs
Correct Answer: B) 1lb
Rationale: In accordance with the law of conservation of mass, matter is neither created nor
destroyed in a closed or open system. One pound of liquid water, when heated to its boiling
point and provided with the latent heat of vaporization, will transform into exactly one
pound of steam vapor.
Question 5
In a low-pressure gas combustion system, what is the function of the "manual reset" valve?
A) It regulates the pressure of the gas
B) It allows the operator to bypass the pilot
C) It is an electric safety valve that cannot be opened until the gas pilot is proven lit
D) It controls the volume of gas based on steam demand
E) It vents gas to the atmosphere during an overpressure event
Correct Answer: C) manual reset
Rationale: The manual reset valve is a critical safety interlock. It is designed to stay closed
to prevent the flow of main gas into the furnace unless specific safety conditions are met—
the primary condition being that a pilot flame is established and "proven" by a flame
scanner. This prevents a buildup of unburned gas that could lead to a furnace explosion.
Question 6
Which component is specifically used for steam loads that require "dry" steam, such as high-
speed steam turbines?
A) Economizers
B) Deaerators
C) Superheaters
D) Feedwater regulators
E) Surface condensers
Correct Answer: C) superheaters
Rationale: Turbines are extremely sensitive to moisture, which can cause erosion and
mechanical damage to the blades. Superheaters heat the steam to a temperature above its
, Page 3
saturation point, ensuring that no liquid water droplets remain. This results in "dry" steam
and significantly higher thermal efficiency for power generation cycles.
Question 7
In a standard feedwater piping arrangement, why is the stop valve located closest to the boiler
shell?
A) To increase the pressure of the water
B) To allow the check valve to be repaired without draining the boiler
C) To prevent the boiler from overfilling
D) To cool the water before it enters the drum
E) To measure the flow of water
Correct Answer: B) stop
Rationale: By placing a manual stop valve between the boiler and the check valve, the
operator can isolate the boiler pressure. This allows for the maintenance or replacement of
the check valve (which is prone to wear) while the boiler remains under pressure and full of
water, avoiding a costly and time-consuming "dump" and restart.
Question 8
In an operating boiler, if the feedwater supply is lost, approximately how long might it take for
the water level in the gauge glass to drop from half full to completely empty?
A) Several hours
B) 30 to 45 minutes
C) A matter of minutes
D) Less than 10 seconds
E) It will never go empty due to the steam pressure
Correct Answer: C) minutes
Rationale: Modern boilers, especially water-tube designs, have a relatively small water
volume compared to their evaporation rate. If the feedwater pump fails while the boiler is
at high fire, the remaining water is converted to steam very rapidly. This makes the water
level one of the most critical variables for the engineer to monitor constantly.
Question 9
What is the primary operational advantage of installing "duplex strainers" in a fuel oil supply
system?
A) They increase the fuel pressure
B) They heat the oil automatically
C) They permit one strainer to be cleaned while the other remains in service
D) They separate water from the oil using centrifugal force
E) They mix different grades of oil together
Correct Answer: C) permit one strainer to be cleaned while the other is in service
Rationale: Continuous operation is vital in steam plants. A duplex strainer consists of two
strainer baskets and a diverter valve. If one basket becomes clogged with debris, the
, Page 4
operator can switch the flow to the clean basket without shutting down the fuel supply to
the burner, ensuring uninterrupted combustion.
Question 10
When comparing superheated steam to saturated steam at the identical pressure, superheated
steam will always possess more:
A) Volume
B) Moisture
C) Heat energy (Enthalpy)
D) Liquid particles
E) Density
Correct Answer: C) heat energy
Rationale: Superheating is the process of adding "sensible heat" to steam after it has
already absorbed the "latent heat" required to change state. Because the temperature of
superheated steam is higher than the saturation temperature for its pressure, its total
enthalpy (BTU content) is significantly higher, allowing it to do more work.
Question 11
To ensure a positive suction head and prevent cavitation in the feedwater pumps, where is the
deaerator traditionally located?
A) In the basement below the pumps
B) Directly on the floor next to the pumps
C) Above the feedwater pumps
D) On the roof of the building
E) Inside the boiler drum
Correct Answer: C) above the feedwater pumps
Rationale: Feedwater in a deaerator is at or near its boiling point. If the pressure at the
pump suction drops, the water will "flash" into steam, causing cavitation. Elevating the
deaerator provides "Static Head" (pressure due to gravity), which ensures the Net Positive
Suction Head (NPSH) is high enough to keep the water in a liquid state as it enters the
pump.
Question 12
On a high-pressure gas system, the gas pilot line provides fuel through which type of valve to the
pressure regulator?
A) Needle valve
B) Check valve
C) Shutoff valve
D) Blowdown valve
E) Safety valve
Correct Answer: C) shutoff
Rationale: A manual shutoff valve is required on the pilot gas line to allow for the complete
