DC 1ST CLASS BOILER EXAM 2025
QUESTIONS AND ANSWERS
Moving blading in which space between blades is the same size at the blading inlet, and the
blading outlet. - ANS Impulse Blading
To blowdown a boiler equipped with a quick opening and slow opening valve on the bottom
blowdown line, the_________. - ANS quick opening valve is opened first and closed last.
Hardness of water is the measurement in ppm of ________ and ________ in the water. -
ANS 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? - ANS HP=5.1 HP= (Head in
Feet) x (Weight in Lbs.)/ 33,000 x Efficiency
a duplex double-acting reciprocating feed water pump has____ - ANS 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. - ANS Selective Catalytic Reduction
Spalling in a boiler occurs in the ____? - ANS 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 ______? - ANS Pyrolysis
1
Page
@COPYRIGHT FYNDLAY 2025/2026
, What is the primary purpose of using wet scrubbers? - ANS 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_______? - ANS 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. - ANS Reverse osmosis
The airflow switch at the burner fan housing______. - ANS 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? - ANS 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? - ANS 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 - ANS process variable
Although boiler tubes and boiler drums withstand the same pressure, the walls of the boiler
tubes are much thinner because ______. - ANS The tubes are much smaller in diameter
A lead sulfide cell detects_____. - ANS Burner pilot and main flame
Which of the following indicates a malfunction in the DC heater? 1. The boiler requires
excessive amounts of oxygen absorbing chemicals.
2.Water and steam are entering the DC heater at the same temperature. - ANS Both 1 & 2
2
______ is the plasticity exhibited by a material under tension loading. - ANS Ductility
Page
@COPYRIGHT FYNDLAY 2025/2026
QUESTIONS AND ANSWERS
Moving blading in which space between blades is the same size at the blading inlet, and the
blading outlet. - ANS Impulse Blading
To blowdown a boiler equipped with a quick opening and slow opening valve on the bottom
blowdown line, the_________. - ANS quick opening valve is opened first and closed last.
Hardness of water is the measurement in ppm of ________ and ________ in the water. -
ANS 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? - ANS HP=5.1 HP= (Head in
Feet) x (Weight in Lbs.)/ 33,000 x Efficiency
a duplex double-acting reciprocating feed water pump has____ - ANS 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. - ANS Selective Catalytic Reduction
Spalling in a boiler occurs in the ____? - ANS 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 ______? - ANS Pyrolysis
1
Page
@COPYRIGHT FYNDLAY 2025/2026
, What is the primary purpose of using wet scrubbers? - ANS 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_______? - ANS 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. - ANS Reverse osmosis
The airflow switch at the burner fan housing______. - ANS 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? - ANS 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? - ANS 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 - ANS process variable
Although boiler tubes and boiler drums withstand the same pressure, the walls of the boiler
tubes are much thinner because ______. - ANS The tubes are much smaller in diameter
A lead sulfide cell detects_____. - ANS Burner pilot and main flame
Which of the following indicates a malfunction in the DC heater? 1. The boiler requires
excessive amounts of oxygen absorbing chemicals.
2.Water and steam are entering the DC heater at the same temperature. - ANS Both 1 & 2
2
______ is the plasticity exhibited by a material under tension loading. - ANS Ductility
Page
@COPYRIGHT FYNDLAY 2025/2026
