STATIONARY ENGINEER 2026 CORE EXAM TEST
QUESTIONS AND SOLUTIONS RATED A+
✔✔How is moisture removed from a refrigerant system? - ✔✔filter dryer
✔✔What type of gas DONT you use to leak test an AC system? - ✔✔OXYGEN
✔✔What is the maximum voltage on a boiler control circuit? - ✔✔150 VOLTS
✔✔A fuel oil that has an API of 32 has how many btus per lb of heating? - ✔✔19490
✔✔Which fuel oils need heating? - ✔✔#4;#5;#6
✔✔What size pipe is used as a header in a boiler operating at 100 psi? - ✔✔6 inches
✔✔What function can an operator contribute towards boiler function? - ✔✔saftey -
efficiency - log plant readings
✔✔How is heat transferred in a boiler ? - ✔✔CONVECTION - CONDUCTION -
RADIATION
✔✔What is not an organic sludge conditioner? - ✔✔Amines
✔✔Which by-product has the largest heating value? - ✔✔Butane
✔✔An increase in 10-20 degrees can reduce creep life by how manuy years - ✔✔10-20
✔✔which coal burns with a yellow flame? - ✔✔Bituminous
✔✔What nondestructive testing is best for testing thickness of plates and tubes? -
✔✔Ultrasound
✔✔On a 2"valve auxillary staem what valves are needed? - ✔✔Single supply OS&Y
✔✔What are the min and max size of a safely valve per code for boilers? - ✔✔Min 3/4
and max 4 1/2
✔✔What stamp is put on a safety valve after its been repairs? - ✔✔VR stamp
✔✔How often do you test your float controls on a hot water boiler? - ✔✔Weekly
✔✔How often do you test a safety valve with pressure? - ✔✔Annually
,✔✔How often do you test a safety valve with a lever test? - ✔✔Monthly
✔✔This part of the safety valve works in conjunction with the adjusting ring to allow it to
pop open. - ✔✔Huddling Chamber
✔✔What do you do if a safety valve is leaking? - ✔✔Reground seat
✔✔A safety valve discharge pipe should go how high when workers maybe present? -
✔✔6 feet high
✔✔If 2 safety valves are used with the same discharge pipe the discharge line must
have - ✔✔The same area as both valves area
✔✔Every discharge valve should have what size drain? - ✔✔3/8 to 1/2 drain
✔✔What are the Blowback setting on a safety valve? - ✔✔Up to 4% but not less than 2
lbs
✔✔Safety valve plate has; - ✔✔Manufacturer's name or trade mark- type or design# -
Size - seat dial - set pressure -blowdown - Discharge capacity lb per hr - capacity lift -
AMSE symbol or NB stamping.
✔✔What percentage of boiler pressure is needed to hand check a boiler safety valve? -
✔✔75%
✔✔On an open air expansion tank hot boiler system; How high should it be mounted? -
✔✔4 feet above the highest heating element.
✔✔What is the minimum clearance of boilers without manhole covers on top? - ✔✔2 ft
✔✔Under what code are oil fired boilers & their control systems covered? - ✔✔Listed &
labeled in accordance with UL 726.NFPA 8501
✔✔How high is a pull station mounted on a wall? - ✔✔48 inches
✔✔When working in a boiler; work permits should be acquired? - ✔✔For the work shift.
✔✔To inspect a boiler they must be what? - ✔✔Be employed either by the state or by
an insurance company licensed to write boiler and pressure vessel insurance in that
jurisdiction
✔✔ASME CSD 1 requires the main gas burners train to have what? - ✔✔2 manual
safety shutoff valves
,✔✔Welds must be approved and witnessed who? - ✔✔Authorized inspector.
✔✔Hydrostatic test is done at what pressure? - ✔✔1.5 times the MAWP or 50% over
MAWP
✔✔During a hydro test if the boiler leaks who do you notify? - ✔✔Authorized boiler
inspector and they will advise you what to do.
✔✔How many low water cut offs are needed per code for hot water boiler systems? -
✔✔When the boiler has an input greater than 400 000 BTU's per hr 1 L.W. cutout is
needed
✔✔What are the minimum and maximum sizes permitted for blowdown valves or
connection? - ✔✔1 min & 2-1/2 max
✔✔If a boiler has 1" blow down pipe; what diameter should the boiler blow down tank air
vent should be? - ✔✔2.5"
✔✔What are 3 low water cutouts? - ✔✔(Float magnet type - it has a plunger on a float
rod an a permanent magnet with a mercury switch) (Float-linkage type- a linkage
connected to a mercury switch) (Submerged-electrode type- uses an electrode make
the complete burner circuit)
✔✔What does a low water cut out do in a low water condition? - ✔✔Shuts off the fuel
supply when it drops below the visible level
✔✔Boiler that exceeds 100 psi must have how many blow downs - ✔✔TWO
✔✔How many times the safety valve setting should the pressure gauge be? - ✔✔1-1/2
to 2 times
✔✔When blowing down the water column you notice the gauge glass slowly returns to
the normal level; this could be indication of what? - ✔✔The bottom of the gauge glass is
clogged and giving a false reading
✔✔How many inches should the lowest visible level in the gauge glass be in a boiler? -
✔✔TWO inches
✔✔What are the minimum gauge glass connection and drain? - ✔✔1/2 connection and
1/4 drain
, ✔✔What must be done if the gauge glass cannot be seen from the operating area? -
✔✔There must be 2 independent remote level indicators installed.
✔✔Blowdown shall not be less than __ or lower than __ of the safety valve? - ✔✔Less
than 2 lbs or lower than 96% of the safety valve
✔✔Blow down valves fitting should be designed at least __ % greater pressure than the
MAWP? - ✔✔25%
✔✔What are two types of commonly used feed water pumps - ✔✔Injectors and
Inspirator
✔✔How does steam flow through pipes? - ✔✔Larger diameter slower the flow Smaller
diameter higher velocity - Pressure difference draws flow
✔✔An acid is a compound that yeilds ________ ions and has a pH value lower than 7. -
✔✔hydrogen
✔✔A base is a compound that yields __________ ions and has a pH value greater than
7. - ✔✔hydroxyl
✔✔A _________ is a gelatin like sustance that has very small particles in suspension.
These particles are usually less than ___ microns in size. - ✔✔colloidal 0.2
✔✔One grain is equal to ______ parts per million. ________ grains equals one pound. -
✔✔17.1 ; 7000
✔✔A solid that is separated from a solution is a_________________. - ✔✔precipate
✔✔All impurities are in one of four states - ✔✔they are ________; __________;
_________; and _________.
✔✔The capacity of a substance to combine with another substance is its
_____________. - ✔✔Valence
✔✔Calcium and Magnesium bicarbonate produce ___________ hardness. -
✔✔temporary
✔✔Scale that is soft and muddy simular to magnesium carbonate
is___________________. - ✔✔calcium carbonate
✔✔In order to prevent corrosion - ✔✔boiler water pH is maintained between
________________.
QUESTIONS AND SOLUTIONS RATED A+
✔✔How is moisture removed from a refrigerant system? - ✔✔filter dryer
✔✔What type of gas DONT you use to leak test an AC system? - ✔✔OXYGEN
✔✔What is the maximum voltage on a boiler control circuit? - ✔✔150 VOLTS
✔✔A fuel oil that has an API of 32 has how many btus per lb of heating? - ✔✔19490
✔✔Which fuel oils need heating? - ✔✔#4;#5;#6
✔✔What size pipe is used as a header in a boiler operating at 100 psi? - ✔✔6 inches
✔✔What function can an operator contribute towards boiler function? - ✔✔saftey -
efficiency - log plant readings
✔✔How is heat transferred in a boiler ? - ✔✔CONVECTION - CONDUCTION -
RADIATION
✔✔What is not an organic sludge conditioner? - ✔✔Amines
✔✔Which by-product has the largest heating value? - ✔✔Butane
✔✔An increase in 10-20 degrees can reduce creep life by how manuy years - ✔✔10-20
✔✔which coal burns with a yellow flame? - ✔✔Bituminous
✔✔What nondestructive testing is best for testing thickness of plates and tubes? -
✔✔Ultrasound
✔✔On a 2"valve auxillary staem what valves are needed? - ✔✔Single supply OS&Y
✔✔What are the min and max size of a safely valve per code for boilers? - ✔✔Min 3/4
and max 4 1/2
✔✔What stamp is put on a safety valve after its been repairs? - ✔✔VR stamp
✔✔How often do you test your float controls on a hot water boiler? - ✔✔Weekly
✔✔How often do you test a safety valve with pressure? - ✔✔Annually
,✔✔How often do you test a safety valve with a lever test? - ✔✔Monthly
✔✔This part of the safety valve works in conjunction with the adjusting ring to allow it to
pop open. - ✔✔Huddling Chamber
✔✔What do you do if a safety valve is leaking? - ✔✔Reground seat
✔✔A safety valve discharge pipe should go how high when workers maybe present? -
✔✔6 feet high
✔✔If 2 safety valves are used with the same discharge pipe the discharge line must
have - ✔✔The same area as both valves area
✔✔Every discharge valve should have what size drain? - ✔✔3/8 to 1/2 drain
✔✔What are the Blowback setting on a safety valve? - ✔✔Up to 4% but not less than 2
lbs
✔✔Safety valve plate has; - ✔✔Manufacturer's name or trade mark- type or design# -
Size - seat dial - set pressure -blowdown - Discharge capacity lb per hr - capacity lift -
AMSE symbol or NB stamping.
✔✔What percentage of boiler pressure is needed to hand check a boiler safety valve? -
✔✔75%
✔✔On an open air expansion tank hot boiler system; How high should it be mounted? -
✔✔4 feet above the highest heating element.
✔✔What is the minimum clearance of boilers without manhole covers on top? - ✔✔2 ft
✔✔Under what code are oil fired boilers & their control systems covered? - ✔✔Listed &
labeled in accordance with UL 726.NFPA 8501
✔✔How high is a pull station mounted on a wall? - ✔✔48 inches
✔✔When working in a boiler; work permits should be acquired? - ✔✔For the work shift.
✔✔To inspect a boiler they must be what? - ✔✔Be employed either by the state or by
an insurance company licensed to write boiler and pressure vessel insurance in that
jurisdiction
✔✔ASME CSD 1 requires the main gas burners train to have what? - ✔✔2 manual
safety shutoff valves
,✔✔Welds must be approved and witnessed who? - ✔✔Authorized inspector.
✔✔Hydrostatic test is done at what pressure? - ✔✔1.5 times the MAWP or 50% over
MAWP
✔✔During a hydro test if the boiler leaks who do you notify? - ✔✔Authorized boiler
inspector and they will advise you what to do.
✔✔How many low water cut offs are needed per code for hot water boiler systems? -
✔✔When the boiler has an input greater than 400 000 BTU's per hr 1 L.W. cutout is
needed
✔✔What are the minimum and maximum sizes permitted for blowdown valves or
connection? - ✔✔1 min & 2-1/2 max
✔✔If a boiler has 1" blow down pipe; what diameter should the boiler blow down tank air
vent should be? - ✔✔2.5"
✔✔What are 3 low water cutouts? - ✔✔(Float magnet type - it has a plunger on a float
rod an a permanent magnet with a mercury switch) (Float-linkage type- a linkage
connected to a mercury switch) (Submerged-electrode type- uses an electrode make
the complete burner circuit)
✔✔What does a low water cut out do in a low water condition? - ✔✔Shuts off the fuel
supply when it drops below the visible level
✔✔Boiler that exceeds 100 psi must have how many blow downs - ✔✔TWO
✔✔How many times the safety valve setting should the pressure gauge be? - ✔✔1-1/2
to 2 times
✔✔When blowing down the water column you notice the gauge glass slowly returns to
the normal level; this could be indication of what? - ✔✔The bottom of the gauge glass is
clogged and giving a false reading
✔✔How many inches should the lowest visible level in the gauge glass be in a boiler? -
✔✔TWO inches
✔✔What are the minimum gauge glass connection and drain? - ✔✔1/2 connection and
1/4 drain
, ✔✔What must be done if the gauge glass cannot be seen from the operating area? -
✔✔There must be 2 independent remote level indicators installed.
✔✔Blowdown shall not be less than __ or lower than __ of the safety valve? - ✔✔Less
than 2 lbs or lower than 96% of the safety valve
✔✔Blow down valves fitting should be designed at least __ % greater pressure than the
MAWP? - ✔✔25%
✔✔What are two types of commonly used feed water pumps - ✔✔Injectors and
Inspirator
✔✔How does steam flow through pipes? - ✔✔Larger diameter slower the flow Smaller
diameter higher velocity - Pressure difference draws flow
✔✔An acid is a compound that yeilds ________ ions and has a pH value lower than 7. -
✔✔hydrogen
✔✔A base is a compound that yields __________ ions and has a pH value greater than
7. - ✔✔hydroxyl
✔✔A _________ is a gelatin like sustance that has very small particles in suspension.
These particles are usually less than ___ microns in size. - ✔✔colloidal 0.2
✔✔One grain is equal to ______ parts per million. ________ grains equals one pound. -
✔✔17.1 ; 7000
✔✔A solid that is separated from a solution is a_________________. - ✔✔precipate
✔✔All impurities are in one of four states - ✔✔they are ________; __________;
_________; and _________.
✔✔The capacity of a substance to combine with another substance is its
_____________. - ✔✔Valence
✔✔Calcium and Magnesium bicarbonate produce ___________ hardness. -
✔✔temporary
✔✔Scale that is soft and muddy simular to magnesium carbonate
is___________________. - ✔✔calcium carbonate
✔✔In order to prevent corrosion - ✔✔boiler water pH is maintained between
________________.
