DC 1st Class Boiler Exam Questions and
Answers (Latest update 2025)
Moving blading in which space between blades is the same
size at the blading inlet, and the blading outlet. - Correct
Answer ✅Impulse Blading
To blowdown a boiler equipped with a quick opening and slow
opening valve on the bottom blowdown line, the_________. -
Correct Answer ✅quick opening valve is opened first and
closed last.
Hardness of water is the measurement in ppm of ________ and
________ in the water. - Correct Answer ✅calcium and
magnesium
A pump delivers 175 gallons per minute against a pressure of
55 psi; the suction pressure is 15 psi. If a pump is 80%
efficient, what is the horsepower needed? - Correct Answer
✅HP=5.1 HP= (Head in Feet) x (Weight in Lbs.)/ 33,000 x
Efficiency
a duplex double-acting reciprocating feed water pump
has____ - Correct Answer ✅two steam Pistons 2 to 2 2/2
times larger in area than the water piston
,DC 1st Class Boiler Exam Questions and
Answers (Latest update 2025)
Name a technique to control the nitrous oxide emissions. -
Correct Answer ✅Selective Catalytic Reduction
Spalling in a boiler occurs in the ____? - Correct Answer
✅Combustion chamber
A technology in which solid waste is heated in an oxygen
starved atmosphere to break down the solids into a gas is
called ______? - Correct Answer ✅Pyrolysis
What is the primary purpose of using wet scrubbers? -
Correct Answer ✅To remove sulfur dioxides
The thermal efficiency of a boiler with a stack temperature of
750°F and and a furnace temperature of 3200°F is_______? -
Correct Answer ✅75% ((3200-750)/3200) x 100
________is a water-purification process in which the water to
be treated is pressurized and applied against the surface of a
, DC 1st Class Boiler Exam Questions and
Answers (Latest update 2025)
semipermeable membrane. - Correct Answer ✅Reverse
osmosis
The airflow switch at the burner fan housing______. - Correct
Answer ✅Ensures the primary air fan is functioning
How many inches of steam space in a cylinder of an engine
12"x28" and the stroke is 5/8 of its full travel? - Correct
Answer ✅1978. V=AxL V=3.14(6x6)x28x.625= 1978
What is the horsepower requirement of a pump that moves
2500 gpm of water against a head of 475' if the pump is
operating at 58% efficiency? - Correct Answer ✅516.8
HP=Head x Weight/33000 x efficiency. (Head =475, Weight =
2500gpm x 8.33) (475x 20825)/19140
A ______ is the condition that is being controlled - Correct
Answer ✅process variable
Although boiler tubes and boiler drums withstand the same
pressure, the walls of the boiler tubes are much thinner
Answers (Latest update 2025)
Moving blading in which space between blades is the same
size at the blading inlet, and the blading outlet. - Correct
Answer ✅Impulse Blading
To blowdown a boiler equipped with a quick opening and slow
opening valve on the bottom blowdown line, the_________. -
Correct Answer ✅quick opening valve is opened first and
closed last.
Hardness of water is the measurement in ppm of ________ and
________ in the water. - Correct Answer ✅calcium and
magnesium
A pump delivers 175 gallons per minute against a pressure of
55 psi; the suction pressure is 15 psi. If a pump is 80%
efficient, what is the horsepower needed? - Correct Answer
✅HP=5.1 HP= (Head in Feet) x (Weight in Lbs.)/ 33,000 x
Efficiency
a duplex double-acting reciprocating feed water pump
has____ - Correct Answer ✅two steam Pistons 2 to 2 2/2
times larger in area than the water piston
,DC 1st Class Boiler Exam Questions and
Answers (Latest update 2025)
Name a technique to control the nitrous oxide emissions. -
Correct Answer ✅Selective Catalytic Reduction
Spalling in a boiler occurs in the ____? - Correct Answer
✅Combustion chamber
A technology in which solid waste is heated in an oxygen
starved atmosphere to break down the solids into a gas is
called ______? - Correct Answer ✅Pyrolysis
What is the primary purpose of using wet scrubbers? -
Correct Answer ✅To remove sulfur dioxides
The thermal efficiency of a boiler with a stack temperature of
750°F and and a furnace temperature of 3200°F is_______? -
Correct Answer ✅75% ((3200-750)/3200) x 100
________is a water-purification process in which the water to
be treated is pressurized and applied against the surface of a
, DC 1st Class Boiler Exam Questions and
Answers (Latest update 2025)
semipermeable membrane. - Correct Answer ✅Reverse
osmosis
The airflow switch at the burner fan housing______. - Correct
Answer ✅Ensures the primary air fan is functioning
How many inches of steam space in a cylinder of an engine
12"x28" and the stroke is 5/8 of its full travel? - Correct
Answer ✅1978. V=AxL V=3.14(6x6)x28x.625= 1978
What is the horsepower requirement of a pump that moves
2500 gpm of water against a head of 475' if the pump is
operating at 58% efficiency? - Correct Answer ✅516.8
HP=Head x Weight/33000 x efficiency. (Head =475, Weight =
2500gpm x 8.33) (475x 20825)/19140
A ______ is the condition that is being controlled - Correct
Answer ✅process variable
Although boiler tubes and boiler drums withstand the same
pressure, the walls of the boiler tubes are much thinner
