DC 1st Class Boiler questions and answers
2026\2027 A+ Grade
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
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 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 because ______.
- correct answer The tubes are much smaller in diameter
A lead sulfide cell detects_____.
- correct answer Burner pilot and main flame
2026\2027 A+ Grade
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
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 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 because ______.
- correct answer The tubes are much smaller in diameter
A lead sulfide cell detects_____.
- correct answer Burner pilot and main flame
