FDNY WRITTEN EXAM WITH CORRECT
QUESTIONS AND ANSWERS 2025
A more efficient centrifugal compressor operation results from - CORRECT-
ANSWERSLowering the condensing pressure
The heat removed from the refrigerant in a condenser is - CORRECT-
ANSWERSSensible and latent heat
According to the New York City fire code, refrigerant containers must - CORRECT-
ANSWERSBe approved by the US Department of Transportation
The cylinder unloader works by - CORRECT-ANSWERSKeeping the suction valve
opened while the compressor is in the return stroke
In most semi-hermetic compressors, the suction vapor is used to - CORRECT-
ANSWERSCool the motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the - CORRECT-ANSWERSDifference between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable to - CORRECT-
ANSWERSRemove impurities from the system
The type of refrigerant system least likely to leak refrigerant into the building space is -
CORRECT-ANSWERSThe indirect system
The compression ratio for a reciprocating compressor with a suction pressure of 65 PSIG
and a discharge pressure of 120 PSIG is closest to - CORRECT-ANSWERS1.69
A superheated vapor is - CORRECT-ANSWERSDry vapor above the saturation
temperature
, A condenser water pump cavitating is most likely caused by - CORRECT-ANSWERSA
faulty cooling tower water level controller
A centrifugal water pump is known as a lift pump when - CORRECT-ANSWERSThe
water supply to the pump suction inlet is below the pump level
A TXV is used to maintain constant - CORRECT-ANSWERSEvaporator superheat
A chilled water supply of 55°F for human comfort is - CORRECT-ANSWERSToo high
for human comfort purpose
The packing gland of a centrifugal pump serves to - CORRECT-ANSWERSKeep air out
of the pumps when the impeller housing is under negative pressure
Capacity control of a reciprocating hermetic compressor is typically achieved through -
CORRECT-ANSWERSOperation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that -
CORRECT-ANSWERSA pure liquid refrigerant will enter the metering device
If a compressor discharge temperature has dropped significantly and the suction line
pressure is high, this may be caused by - CORRECT-ANSWERSAn expansion valve that
is open too wide
A low side float valve is used to maintain - CORRECT-ANSWERSThe level of the
refrigerant in the evaporator
The ASHRAE refrigerant safety classification indicating no flammability and lower
toxicity is - CORRECT-ANSWERSA1
When an expansion valve is operating properly, the end of the evaporator will contain -
CORRECT-ANSWERSOnly superheated vapor
, Information not contained in a Material Safety Data Sheet (MSDS) includes -
CORRECT-ANSWERSCost of the material
In a steam turbine, the Kingsbury thrust bearing functions to - CORRECT-
ANSWERSMaintain axial positioning of the rotor shaft
A centrifugal water pump is considered fully primed when - CORRECT-ANSWERSThe
pump is full of liquid
To avoid collapsing tubing when making bends, a refrigerant engineer should use -
CORRECT-ANSWERSLever type tubing bender
A reciprocating compressor making a clicking sound during operation, if not caused by
worn parts, is probably due to - CORRECT-ANSWERSSlugging of the liquid refrigerant
For a refrigerant to become superheated, it must be heated in a section of the low side
refrigerant line - CORRECT-ANSWERSWhere no liquid refrigerant is present
After all liquid refrigerant has been recovered, the system - CORRECT-
ANSWERSShould not be opened until all vapor has been recovered
The removal rate of refrigerant using a portable compressor recovery unit gradually slows
down because - CORRECT-ANSWERSThe vapor density is decreasing
If the water level in all cooling tower cells is very low, the immediate action should be to
- CORRECT-ANSWERSAdd additional makeup water to the cooling tower
The height of the water column, in feet, with a pressure gauge reading 140 PSIG is
closest to - CORRECT-ANSWERS323 feet
The device that protects a steam turbine from excessive speed is the - CORRECT-
ANSWERSGovernor assembly
QUESTIONS AND ANSWERS 2025
A more efficient centrifugal compressor operation results from - CORRECT-
ANSWERSLowering the condensing pressure
The heat removed from the refrigerant in a condenser is - CORRECT-
ANSWERSSensible and latent heat
According to the New York City fire code, refrigerant containers must - CORRECT-
ANSWERSBe approved by the US Department of Transportation
The cylinder unloader works by - CORRECT-ANSWERSKeeping the suction valve
opened while the compressor is in the return stroke
In most semi-hermetic compressors, the suction vapor is used to - CORRECT-
ANSWERSCool the motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the - CORRECT-ANSWERSDifference between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable to - CORRECT-
ANSWERSRemove impurities from the system
The type of refrigerant system least likely to leak refrigerant into the building space is -
CORRECT-ANSWERSThe indirect system
The compression ratio for a reciprocating compressor with a suction pressure of 65 PSIG
and a discharge pressure of 120 PSIG is closest to - CORRECT-ANSWERS1.69
A superheated vapor is - CORRECT-ANSWERSDry vapor above the saturation
temperature
, A condenser water pump cavitating is most likely caused by - CORRECT-ANSWERSA
faulty cooling tower water level controller
A centrifugal water pump is known as a lift pump when - CORRECT-ANSWERSThe
water supply to the pump suction inlet is below the pump level
A TXV is used to maintain constant - CORRECT-ANSWERSEvaporator superheat
A chilled water supply of 55°F for human comfort is - CORRECT-ANSWERSToo high
for human comfort purpose
The packing gland of a centrifugal pump serves to - CORRECT-ANSWERSKeep air out
of the pumps when the impeller housing is under negative pressure
Capacity control of a reciprocating hermetic compressor is typically achieved through -
CORRECT-ANSWERSOperation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that -
CORRECT-ANSWERSA pure liquid refrigerant will enter the metering device
If a compressor discharge temperature has dropped significantly and the suction line
pressure is high, this may be caused by - CORRECT-ANSWERSAn expansion valve that
is open too wide
A low side float valve is used to maintain - CORRECT-ANSWERSThe level of the
refrigerant in the evaporator
The ASHRAE refrigerant safety classification indicating no flammability and lower
toxicity is - CORRECT-ANSWERSA1
When an expansion valve is operating properly, the end of the evaporator will contain -
CORRECT-ANSWERSOnly superheated vapor
, Information not contained in a Material Safety Data Sheet (MSDS) includes -
CORRECT-ANSWERSCost of the material
In a steam turbine, the Kingsbury thrust bearing functions to - CORRECT-
ANSWERSMaintain axial positioning of the rotor shaft
A centrifugal water pump is considered fully primed when - CORRECT-ANSWERSThe
pump is full of liquid
To avoid collapsing tubing when making bends, a refrigerant engineer should use -
CORRECT-ANSWERSLever type tubing bender
A reciprocating compressor making a clicking sound during operation, if not caused by
worn parts, is probably due to - CORRECT-ANSWERSSlugging of the liquid refrigerant
For a refrigerant to become superheated, it must be heated in a section of the low side
refrigerant line - CORRECT-ANSWERSWhere no liquid refrigerant is present
After all liquid refrigerant has been recovered, the system - CORRECT-
ANSWERSShould not be opened until all vapor has been recovered
The removal rate of refrigerant using a portable compressor recovery unit gradually slows
down because - CORRECT-ANSWERSThe vapor density is decreasing
If the water level in all cooling tower cells is very low, the immediate action should be to
- CORRECT-ANSWERSAdd additional makeup water to the cooling tower
The height of the water column, in feet, with a pressure gauge reading 140 PSIG is
closest to - CORRECT-ANSWERS323 feet
The device that protects a steam turbine from excessive speed is the - CORRECT-
ANSWERSGovernor assembly
