DC BOILER & STATIONARY Test Exam 2026–
2027 Real Exam Questions and Correct Answers
| Graded A+ | Guaranteed Pass!!
With normal oxygen and low alkalinity, what is added to boiler water? -
ANSWERNeutralizing Amines
What is hard forming scale? - ANSWER-Silica
What takes no actual action in combustion? - ANSWER-Nitrogen
With hydroxide present and normal oxygen levels which chemical will cause problem? -
ANSWER- Chlorine
Which chemicals are used to combat scale? - ANSWER-Combined Phosphate Treatment
Which compound not heat produce? - ANSWER-Nitrogen
What mechanical device is used to remove scale from Fire Tubes? - ANSWER-A Tube
Rattler or Vibrator is used (page 623)
Who can make Adjustments or repairs on a Safety Valve? - ANSWER-Qualify person from
Manufacturer or Representative
,What mechanical device is used to remove scale from water Tubes? - ANSWER-A Tube
Turbine is used
In a duct air handling system, space thermostat control building temperatures by? -
ANSWERMixing 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 dehumification? -
ANSWER- Passive
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? - ANSWER-A 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? - ANSWER-Multi zone
A duplex reciprocating pump runs at 75 rpm. The pump is a 12 x 5 x 12, Operating with 7%
slip. What is the capacity of the pump?
GPM = LANE
231 - ANSWER-GPM = 12 x (5 x 5 x 0.7854) x 75 x 2 x (1-0.07)
231
GPM = 32868.99
231
GPM = 142.29 gpm.
,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? - ANSWER-160 (10 x 24 x 2/3 ) =160
In a dual duct air handling system space thermostatic control building temperature by? -
ANSWER- Moving the air from the hot & cold duct in a molding box serving the space
In a multi-zone air handler unit, the zone thermostat controls the zone temperature by? -
ANSWER- Dampers that control the air flow from the hot & cold deck
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? - ANSWER-Dual duct
A boiler is rated at (86,250 lbs, 88,250 lbs, 96,250 lbs) of steam per hour. What is the
equivalent boiler horsepower? - ANSWER-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? - ANSWER-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? - ANSWER-150.79 TF = 150.79
The expansion tank on a closed loop system should be located? - ANSWER-On the suction
side of the pump
What is the primary purpose of a crank case heater on a reciprocating chiller? - ANSWERTo
prevent refrigeration migration
, What is meant by the percent of (skip, step, and slip) in a pump? - ANSWER-Percentage of
flow compared minimum speed and full speed
e. The difference in theoretical capacity compared to the actual capacity
What is meant by a pump becoming steam bound? - ANSWER-When the static pressure at
the suction of the pump falls below the vapor pressure corresponding to its temperature.
62.Which of the following is a positive displacement pump? - ANSWER-Reciprocating
The heart of a refrigeration system is the ? - ANSWER-Compressor
Refrigerant flow into the evaporator is controlled by ? - ANSWER-A metering device
What does the whistle on the top of the water column indicating? - ANSWER-High and low
water condition
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? - ANSWER-4
= 4:1 2nd choice
The part of the refrigeration system that absorbs heat into the system is controlled by the
? - ANSWER-Evaporator
2027 Real Exam Questions and Correct Answers
| Graded A+ | Guaranteed Pass!!
With normal oxygen and low alkalinity, what is added to boiler water? -
ANSWERNeutralizing Amines
What is hard forming scale? - ANSWER-Silica
What takes no actual action in combustion? - ANSWER-Nitrogen
With hydroxide present and normal oxygen levels which chemical will cause problem? -
ANSWER- Chlorine
Which chemicals are used to combat scale? - ANSWER-Combined Phosphate Treatment
Which compound not heat produce? - ANSWER-Nitrogen
What mechanical device is used to remove scale from Fire Tubes? - ANSWER-A Tube
Rattler or Vibrator is used (page 623)
Who can make Adjustments or repairs on a Safety Valve? - ANSWER-Qualify person from
Manufacturer or Representative
,What mechanical device is used to remove scale from water Tubes? - ANSWER-A Tube
Turbine is used
In a duct air handling system, space thermostat control building temperatures by? -
ANSWERMixing 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 dehumification? -
ANSWER- Passive
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? - ANSWER-A 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? - ANSWER-Multi zone
A duplex reciprocating pump runs at 75 rpm. The pump is a 12 x 5 x 12, Operating with 7%
slip. What is the capacity of the pump?
GPM = LANE
231 - ANSWER-GPM = 12 x (5 x 5 x 0.7854) x 75 x 2 x (1-0.07)
231
GPM = 32868.99
231
GPM = 142.29 gpm.
,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? - ANSWER-160 (10 x 24 x 2/3 ) =160
In a dual duct air handling system space thermostatic control building temperature by? -
ANSWER- Moving the air from the hot & cold duct in a molding box serving the space
In a multi-zone air handler unit, the zone thermostat controls the zone temperature by? -
ANSWER- Dampers that control the air flow from the hot & cold deck
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? - ANSWER-Dual duct
A boiler is rated at (86,250 lbs, 88,250 lbs, 96,250 lbs) of steam per hour. What is the
equivalent boiler horsepower? - ANSWER-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? - ANSWER-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? - ANSWER-150.79 TF = 150.79
The expansion tank on a closed loop system should be located? - ANSWER-On the suction
side of the pump
What is the primary purpose of a crank case heater on a reciprocating chiller? - ANSWERTo
prevent refrigeration migration
, What is meant by the percent of (skip, step, and slip) in a pump? - ANSWER-Percentage of
flow compared minimum speed and full speed
e. The difference in theoretical capacity compared to the actual capacity
What is meant by a pump becoming steam bound? - ANSWER-When the static pressure at
the suction of the pump falls below the vapor pressure corresponding to its temperature.
62.Which of the following is a positive displacement pump? - ANSWER-Reciprocating
The heart of a refrigeration system is the ? - ANSWER-Compressor
Refrigerant flow into the evaporator is controlled by ? - ANSWER-A metering device
What does the whistle on the top of the water column indicating? - ANSWER-High and low
water condition
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? - ANSWER-4
= 4:1 2nd choice
The part of the refrigeration system that absorbs heat into the system is controlled by the
? - ANSWER-Evaporator
