DC 3rd Class Test, 3rd class stationary steam
engineer license prep, Stationary Engineer,
Station engineer exam, DC 1st Class Boiler
Updated Exam 2026 WITH Recent Newest
Verified And Well Analyzed Exam Questions
(Actual Exam 2026-2027) Correct Detailed &
Verified ANSWERS (100% Accurate Solutions)
ALREADY GRADED A+||NEWEST VERSION Of
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What mechanical device is used to remove scale from Fire Tubes? - ANSWERS-A
Tube Rattler or Vibrator is used
What is not an advantage of the economic type boiler over the conventional type boiler?
- ANSWERS-Allows greater flexibility expansion and contraction
An accelerated circulation water tube is one characterized by? - ANSWERS-Heated
down comers
Why is platinum used in RTD (Resistive temperature Device)? - ANSWERS-Because of
its stability at high temperature
In HVAC system's,controlled by a thermostat,the difference is the difference between
the? - ANSWERS-Set point and the temperature at which the switch turns the systems
off
What is the purpose of a suction accumulator? - ANSWERS-It contains liquid refrigerant
to allow evaporation prior to entering the compressor
,What must be submitted to the code official when field assembly of boilers is required? -
ANSWERS-Boiler inspection report
A boiler has 2800 furnaces temperature and 600 stack temperatures reading. What is
the boiler efficiency? (Page 646 BOG) - ANSWERS-78.57 Input - loss x 100 divided by
Input (2800 - 600) x 100/ 2800 = 78.57
What do you call a reading from the center of an impeller across to the gauge? -
ANSWERS-Static pressure
What is the heart of a refrigeration system? - ANSWERS-compressor
Which coal has the biggest level of fixed carbon content? - ANSWERS-Anthracite =
14,000
Who can make Adjustments or repairs on a Safety Valve? - ANSWERS-Qualify person
from Manufacturer or Representative
What mechanical device is used to remove scale from water Tubes? - ANSWERS-A
Tube Turbine is used
In a duct air handling system, space thermostat control building temperatures by? -
ANSWERS-Mixing the air from hot & cold duct in a mixing box serving the space
The removal of moisture from air using a cooling coil is called _________
dehumidification? - ANSWERS-Passive
In a multi-zone air handler unit, the zone thermostat controls the zone temperature by? -
ANSWERS-Dampers that control the air flow from the hot & cold duct
An air handler unit that has hot & cold air ducts connected to (molding boxes?) located
in each building space is called a __________air handler unit? - ANSWERS-dual duct
,An air handler unit supplies a constant supply air temperature of 55 degree F to building
spaces and includes a coil called _____air handler unit? - ANSWERS-terminal reheat
An air handler unit that provides heating, cooling, ventilation, and air conditioning to
more than one building or area and has its cooling & heating Coil in separate side-by
side ducts is called a _______air handling unit? - ANSWERS-multi-zone
In a dual duct air handling system space thermostatic controls building temperature by?
- ANSWERS-Moving the air from the hot & cold duct in a molding box serving the
space.
A boiler is rated at (86,250 lbs, 88,250 lbs, 96,250 lbs) of steam per hour. What is the
equivalent boiler horsepower? - ANSWERS-2500 HP = 86,.5 = 2500 lbs
What is the area of a steam engine cylinder reading 10 x 24, when the piston is only
travelling at 2/3 of the way? - ANSWERS-160. (10 x 24 x 2/3 ) =160
What is the total force acting on a 4 inches diameter safety value disc with a boiler
pressure of 12 psi? - ANSWERS-150.79 TF= P x A
The expansion tank on a closed loop system should be located? - ANSWERS-Suction
side of the pump
What is the primary purpose of a crank case heater on a reciprocating chiller? -
ANSWERS-To prevent refrigeration migration
What is meant by the percent of (skip, step, and slip) in a pump? - ANSWERS-The
difference in theoretical capacity compared to the actual capacity
The vertical distance from the center line of the pump up to the top level of the supply
tank is called? - ANSWERS-Static suction head
, Where in a system is a foot valve value installed and what is its purpose? - ANSWERS-
A type of check value located below the normal level of the tank attached to the end of
the suction line of the pump, used to keep suction line full to facilitate starting.
In a multi-zone air handling unit, the zone thermostat controls the zone temperature by?
- ANSWERS-Dampers that control the air flow from the hot & cold deck
What is meant by a pump becoming steam bound? - ANSWERS-When the static
pressure at the suction of the pump falls below the vapor pressure corresponding to its
temperature.
What does the whistle on the top of the water column indicating? - ANSWERS-High and
low water condition
The heart of a refrigeration system is the _______? - ANSWERS-compressor
Refrigerant flow into the evaporator is controlled by ___________? - ANSWERS-
Metering device
A reciprocating compressor operating with refrigerant R-410 head pressure of 476 psi
and a suction pressure of 118 psi. What is the compressor's compression ratio? -
ANSWERS-3.7 476+14.+14.7 = 3.760
The part of the refrigeration system that absorbs heat into the system is controlled by
the ______? - ANSWERS-evaporator
A replacement refrigerant for R-12 medium and high temperature refrigeration
application is _____? - ANSWERS-134 A
The color for an R-134 a refrigerant cylinder is _______? - ANSWERS-light blue
engineer license prep, Stationary Engineer,
Station engineer exam, DC 1st Class Boiler
Updated Exam 2026 WITH Recent Newest
Verified And Well Analyzed Exam Questions
(Actual Exam 2026-2027) Correct Detailed &
Verified ANSWERS (100% Accurate Solutions)
ALREADY GRADED A+||NEWEST VERSION Of
The Exam Guarantee Pass!!
What mechanical device is used to remove scale from Fire Tubes? - ANSWERS-A
Tube Rattler or Vibrator is used
What is not an advantage of the economic type boiler over the conventional type boiler?
- ANSWERS-Allows greater flexibility expansion and contraction
An accelerated circulation water tube is one characterized by? - ANSWERS-Heated
down comers
Why is platinum used in RTD (Resistive temperature Device)? - ANSWERS-Because of
its stability at high temperature
In HVAC system's,controlled by a thermostat,the difference is the difference between
the? - ANSWERS-Set point and the temperature at which the switch turns the systems
off
What is the purpose of a suction accumulator? - ANSWERS-It contains liquid refrigerant
to allow evaporation prior to entering the compressor
,What must be submitted to the code official when field assembly of boilers is required? -
ANSWERS-Boiler inspection report
A boiler has 2800 furnaces temperature and 600 stack temperatures reading. What is
the boiler efficiency? (Page 646 BOG) - ANSWERS-78.57 Input - loss x 100 divided by
Input (2800 - 600) x 100/ 2800 = 78.57
What do you call a reading from the center of an impeller across to the gauge? -
ANSWERS-Static pressure
What is the heart of a refrigeration system? - ANSWERS-compressor
Which coal has the biggest level of fixed carbon content? - ANSWERS-Anthracite =
14,000
Who can make Adjustments or repairs on a Safety Valve? - ANSWERS-Qualify person
from Manufacturer or Representative
What mechanical device is used to remove scale from water Tubes? - ANSWERS-A
Tube Turbine is used
In a duct air handling system, space thermostat control building temperatures by? -
ANSWERS-Mixing the air from hot & cold duct in a mixing box serving the space
The removal of moisture from air using a cooling coil is called _________
dehumidification? - ANSWERS-Passive
In a multi-zone air handler unit, the zone thermostat controls the zone temperature by? -
ANSWERS-Dampers that control the air flow from the hot & cold duct
An air handler unit that has hot & cold air ducts connected to (molding boxes?) located
in each building space is called a __________air handler unit? - ANSWERS-dual duct
,An air handler unit supplies a constant supply air temperature of 55 degree F to building
spaces and includes a coil called _____air handler unit? - ANSWERS-terminal reheat
An air handler unit that provides heating, cooling, ventilation, and air conditioning to
more than one building or area and has its cooling & heating Coil in separate side-by
side ducts is called a _______air handling unit? - ANSWERS-multi-zone
In a dual duct air handling system space thermostatic controls building temperature by?
- ANSWERS-Moving the air from the hot & cold duct in a molding box serving the
space.
A boiler is rated at (86,250 lbs, 88,250 lbs, 96,250 lbs) of steam per hour. What is the
equivalent boiler horsepower? - ANSWERS-2500 HP = 86,.5 = 2500 lbs
What is the area of a steam engine cylinder reading 10 x 24, when the piston is only
travelling at 2/3 of the way? - ANSWERS-160. (10 x 24 x 2/3 ) =160
What is the total force acting on a 4 inches diameter safety value disc with a boiler
pressure of 12 psi? - ANSWERS-150.79 TF= P x A
The expansion tank on a closed loop system should be located? - ANSWERS-Suction
side of the pump
What is the primary purpose of a crank case heater on a reciprocating chiller? -
ANSWERS-To prevent refrigeration migration
What is meant by the percent of (skip, step, and slip) in a pump? - ANSWERS-The
difference in theoretical capacity compared to the actual capacity
The vertical distance from the center line of the pump up to the top level of the supply
tank is called? - ANSWERS-Static suction head
, Where in a system is a foot valve value installed and what is its purpose? - ANSWERS-
A type of check value located below the normal level of the tank attached to the end of
the suction line of the pump, used to keep suction line full to facilitate starting.
In a multi-zone air handling unit, the zone thermostat controls the zone temperature by?
- ANSWERS-Dampers that control the air flow from the hot & cold deck
What is meant by a pump becoming steam bound? - ANSWERS-When the static
pressure at the suction of the pump falls below the vapor pressure corresponding to its
temperature.
What does the whistle on the top of the water column indicating? - ANSWERS-High and
low water condition
The heart of a refrigeration system is the _______? - ANSWERS-compressor
Refrigerant flow into the evaporator is controlled by ___________? - ANSWERS-
Metering device
A reciprocating compressor operating with refrigerant R-410 head pressure of 476 psi
and a suction pressure of 118 psi. What is the compressor's compression ratio? -
ANSWERS-3.7 476+14.+14.7 = 3.760
The part of the refrigeration system that absorbs heat into the system is controlled by
the ______? - ANSWERS-evaporator
A replacement refrigerant for R-12 medium and high temperature refrigeration
application is _____? - ANSWERS-134 A
The color for an R-134 a refrigerant cylinder is _______? - ANSWERS-light blue
