DC 3RD CLASS BOILER 2026 EXAMS TEST QUESTIONS AND
ANSWERS GRADED A+
✔✔A turbine valve designed to prevent the turbine from overheating during a turbine trip
or shutdown by discharging hot, trapped steam to a low pressure area. - ✔✔ventilator
valve
✔✔A(n) ______ gas is a gas that does not change into a liquid when its temperature is
reduced. - ✔✔non-condensable
✔✔The boilers in a boiler installation are consuming a total of 780 gallons of fuel per
hour. The fuel oil storage tank is a vertical cylinder tank that is 18 feet in diameter. The
tank currently contains 14'6" of oil. At the current fuel oil consumption rate, how many
hours will the fuel oil supply last? - ✔✔35.4 hours. V=A x L (3.14 (9x9) x 14.5 x
7.48)/780
✔✔A _____ is a metal brace on a HRT boiler used to attach a wall to steel framework
that supports the wall - ✔✔buckstay
✔✔Find the stress in pounds per square inch on a stably 2.75" in diameter, stays are
pitched 26" x 9". Boiler is operating at 450psi. - ✔✔17,730.
TF= P x A
26 x 9x 450=105,300
P=F/A
105,300/3.14(1.375 x 1.375)
✔✔A bearing consisting of two thrust plates, which surround a turbine shaft and on
thrust runner, which is an integral part of the shaft. Axial rotor movement is prevented
by the thrust plates blocking the movement of the thrust runner. - ✔✔Thrust bearing
✔✔In a three-element feedwater regulating system, ______ are measured. - ✔✔steam
flow, feedwater flow, and water level
✔✔A sectional (sinuous) header boiler is classified as which type? - ✔✔Straight tube
✔✔What is the last valve to be closed before lighting off? - ✔✔Economizer vent
✔✔A ______ boiler is water tube boiler design which three steam and water drums on
the top and a mud drum beneath, interconnected by a large number of water tubes. -
✔✔Sterling
✔✔_______ combustion control ensures that an oxygen-deficient condition is not
encountered, especially during load changes - ✔✔Cross-limiting
, ✔✔Pumps of the centrifugal type are generally manufactured in either of two general
designs: turbine with a diffuser ring or volute without a diffuser ring. In the volute
designed pumps the discharge chamber acts as a diffuser. The primary purpose for the
use of a diffuser ring or chamber is to_____. - ✔✔Convert high velocity to pressure
✔✔A thermo-expansion feedwater regulator operated on ______. - ✔✔expansion and
contraction of a thermostatic element
✔✔_______ is the weight of a given volume of material divided by the weight of an
equal volume of water when both are measured at the same temperature (typically
60°F) - ✔✔Specific gravity
✔✔The conductivity of the make-up water is 390 micromhos. The conductivity of feed
water is 180 micromhos, and the conductivity of the condensate is 45 micromhos. What
is the percentage of condensate return? - ✔✔60.9%. CR= (MC-FC/MC-RC) x 100
✔✔A component of the gland seal system made of grooves and ridges that form
Amazon tortuous path to restrict the passage of a fluid such as air or steam. -
✔✔Labyrinth
✔✔Baffle are used in the steam and water drum of water tube boilers to _____. -
✔✔prevent water carryover with the steam
✔✔A boiler can be hydrostatically tested using water at _____°F. - ✔✔100°. (70°-100°)
✔✔In a boiler room the is a HRT boiler with the following dimensions: Drum is 86" in
diameter and 26 feet long; a total of 120 tubes 4.5" in diameter; boiler shell is bricked in
1/4 of the distance from above. What is the total heating surface? - ✔✔4167 sq/ft
✔✔A raised knob on the end of a moving blade that is peened over shrouding to ricotta
the shrouding to the blading. - ✔✔Tenon
✔✔Which type of waste to energy plants process for the removal of non combustible
materials? - ✔✔refuse derived fuel burning
✔✔Turbine blading that is attached to the shaft and converts the thermal energy in
steam into mechanical energy. - ✔✔Moving blading or buckets
✔✔A flame rod______. - ✔✔Ensure the gas pilot is lighted
✔✔The two types of relays used to start a single-phase hermetic compressor
are_______. - ✔✔Potential relay and current relay
ANSWERS GRADED A+
✔✔A turbine valve designed to prevent the turbine from overheating during a turbine trip
or shutdown by discharging hot, trapped steam to a low pressure area. - ✔✔ventilator
valve
✔✔A(n) ______ gas is a gas that does not change into a liquid when its temperature is
reduced. - ✔✔non-condensable
✔✔The boilers in a boiler installation are consuming a total of 780 gallons of fuel per
hour. The fuel oil storage tank is a vertical cylinder tank that is 18 feet in diameter. The
tank currently contains 14'6" of oil. At the current fuel oil consumption rate, how many
hours will the fuel oil supply last? - ✔✔35.4 hours. V=A x L (3.14 (9x9) x 14.5 x
7.48)/780
✔✔A _____ is a metal brace on a HRT boiler used to attach a wall to steel framework
that supports the wall - ✔✔buckstay
✔✔Find the stress in pounds per square inch on a stably 2.75" in diameter, stays are
pitched 26" x 9". Boiler is operating at 450psi. - ✔✔17,730.
TF= P x A
26 x 9x 450=105,300
P=F/A
105,300/3.14(1.375 x 1.375)
✔✔A bearing consisting of two thrust plates, which surround a turbine shaft and on
thrust runner, which is an integral part of the shaft. Axial rotor movement is prevented
by the thrust plates blocking the movement of the thrust runner. - ✔✔Thrust bearing
✔✔In a three-element feedwater regulating system, ______ are measured. - ✔✔steam
flow, feedwater flow, and water level
✔✔A sectional (sinuous) header boiler is classified as which type? - ✔✔Straight tube
✔✔What is the last valve to be closed before lighting off? - ✔✔Economizer vent
✔✔A ______ boiler is water tube boiler design which three steam and water drums on
the top and a mud drum beneath, interconnected by a large number of water tubes. -
✔✔Sterling
✔✔_______ combustion control ensures that an oxygen-deficient condition is not
encountered, especially during load changes - ✔✔Cross-limiting
, ✔✔Pumps of the centrifugal type are generally manufactured in either of two general
designs: turbine with a diffuser ring or volute without a diffuser ring. In the volute
designed pumps the discharge chamber acts as a diffuser. The primary purpose for the
use of a diffuser ring or chamber is to_____. - ✔✔Convert high velocity to pressure
✔✔A thermo-expansion feedwater regulator operated on ______. - ✔✔expansion and
contraction of a thermostatic element
✔✔_______ is the weight of a given volume of material divided by the weight of an
equal volume of water when both are measured at the same temperature (typically
60°F) - ✔✔Specific gravity
✔✔The conductivity of the make-up water is 390 micromhos. The conductivity of feed
water is 180 micromhos, and the conductivity of the condensate is 45 micromhos. What
is the percentage of condensate return? - ✔✔60.9%. CR= (MC-FC/MC-RC) x 100
✔✔A component of the gland seal system made of grooves and ridges that form
Amazon tortuous path to restrict the passage of a fluid such as air or steam. -
✔✔Labyrinth
✔✔Baffle are used in the steam and water drum of water tube boilers to _____. -
✔✔prevent water carryover with the steam
✔✔A boiler can be hydrostatically tested using water at _____°F. - ✔✔100°. (70°-100°)
✔✔In a boiler room the is a HRT boiler with the following dimensions: Drum is 86" in
diameter and 26 feet long; a total of 120 tubes 4.5" in diameter; boiler shell is bricked in
1/4 of the distance from above. What is the total heating surface? - ✔✔4167 sq/ft
✔✔A raised knob on the end of a moving blade that is peened over shrouding to ricotta
the shrouding to the blading. - ✔✔Tenon
✔✔Which type of waste to energy plants process for the removal of non combustible
materials? - ✔✔refuse derived fuel burning
✔✔Turbine blading that is attached to the shaft and converts the thermal energy in
steam into mechanical energy. - ✔✔Moving blading or buckets
✔✔A flame rod______. - ✔✔Ensure the gas pilot is lighted
✔✔The two types of relays used to start a single-phase hermetic compressor
are_______. - ✔✔Potential relay and current relay
