FDNY Z51 Z-51 REFRIGERATION
EXAM (2026) COMPREHENSIVE
QUESTIONS AND VERIFIED
ANSWERS ACTUAL EXAM 2026
TEST
QUESTIONIn most semi-hermetic compressors, the suction vapor
is used to: - answer-Cool the motor
QUESTIONThe amount of refrigerant that flows through the
orifices of an economizer is determined by the: - answer-
Differences between the high side and low side pressure
QUESTIONThe installation of an inline refrigerant cleaning
system is advisable: - answer-To remove impurities from the
system
QUESTIONThe type of refrigerant system that is least likely to
leak refrigerant into the building space that are being cooled: -
answer-Indirect system
QUESTIONThe suction pressure of a reciprocating compressor is
65 PSIG. The discharge pressure of this compressor is 120 PSIG.
The atmospheric is 14.7 PSI. The compression ratio for the given
condition is closest to: - answer-1.69
,QUESTIONA superheated vapor is: - answer-Dry vapor above the
saturation temperature
QUESTIONA refrigerant engineer verifies that a condenser water
pump is cavitating. Of the following, the most likely cause for this
condition is: - answer-A faulty cooling tower water level controller
Efficiency of the refrigerant cycle is affected by the operations of
the condenser. Of the following, a more efficient centrifugal
compressor operation results from: - answer-Lowering the
condensing pressure
QUESTIONThe heat removed from the refrigerant in a condenser
is: - answer-Sensible and latent heat
QUESTIONThe refrigerant unit that you have been assigned to is
being taken out of service for a major repair. You have been
assigned to withdraw refrigerant for storage in suitable containers.
According to the NYC Fire Code, you must ensure that the
containers: - answer-Are approved by the US Dept. of
Transportation
QUESTIONWhich of the following best describes how the cylinder
unloader works? - answer-Keep in the suction valve opened while
the compressor is in the return stroke
QUESTIONA centrifugal water pump is known as a lift pump
when the: - answer-The water supply to the pump suction inlet is
below the pump level
QUESTIONA TXV is used to maintain constant: - answer-
Evaporator superheat
, QUESTIONThe chilled water supply to the building is 55 deg F. If
the chiller is being used for human comfort, should you be
concerned about this, and why? - answer-Yes, this temp is too
high for human comfort purposes
QUESTIONThe packing gland of a centrifugal pump serves to: -
answer-The drip part of the packing gland gives evidence that
there is water in the pump
QUESTIONCapacity control of reciprocating hermetic compressor
is typically achieved through: - answer-Operation of the hot gas
bypass valve
QUESTIONThe most important reason to sub-cool the refrigerant
in the condenser is to ensure that: - answer-A pure liquid
refrigerant will enter the metering device
QUESTIONIn order for a refrigerant to become superheated, it
must be heated in a section of the low side refrigerant line: -
answer-Where no liquid refrigerant is present
QUESTIONAll liquid has been recovered from a system to be
overhauled, the system: - answer-Should not be opened until all
vapor has been recovered
QUESTIONWhen a refrigerant engineer uses a portable
compressor recovery unit to remove vapor refrigerant from a
refrigeration system the removal rate of the refrigerant will
gradually slow down because? - answer-The compressor
efficiency is decreasing
QUESTIONYou are the engineer running a 2000-ton (steam
driven turbine) centrifugal refrigeration system, a refrigeration
EXAM (2026) COMPREHENSIVE
QUESTIONS AND VERIFIED
ANSWERS ACTUAL EXAM 2026
TEST
QUESTIONIn most semi-hermetic compressors, the suction vapor
is used to: - answer-Cool the motor
QUESTIONThe amount of refrigerant that flows through the
orifices of an economizer is determined by the: - answer-
Differences between the high side and low side pressure
QUESTIONThe installation of an inline refrigerant cleaning
system is advisable: - answer-To remove impurities from the
system
QUESTIONThe type of refrigerant system that is least likely to
leak refrigerant into the building space that are being cooled: -
answer-Indirect system
QUESTIONThe suction pressure of a reciprocating compressor is
65 PSIG. The discharge pressure of this compressor is 120 PSIG.
The atmospheric is 14.7 PSI. The compression ratio for the given
condition is closest to: - answer-1.69
,QUESTIONA superheated vapor is: - answer-Dry vapor above the
saturation temperature
QUESTIONA refrigerant engineer verifies that a condenser water
pump is cavitating. Of the following, the most likely cause for this
condition is: - answer-A faulty cooling tower water level controller
Efficiency of the refrigerant cycle is affected by the operations of
the condenser. Of the following, a more efficient centrifugal
compressor operation results from: - answer-Lowering the
condensing pressure
QUESTIONThe heat removed from the refrigerant in a condenser
is: - answer-Sensible and latent heat
QUESTIONThe refrigerant unit that you have been assigned to is
being taken out of service for a major repair. You have been
assigned to withdraw refrigerant for storage in suitable containers.
According to the NYC Fire Code, you must ensure that the
containers: - answer-Are approved by the US Dept. of
Transportation
QUESTIONWhich of the following best describes how the cylinder
unloader works? - answer-Keep in the suction valve opened while
the compressor is in the return stroke
QUESTIONA centrifugal water pump is known as a lift pump
when the: - answer-The water supply to the pump suction inlet is
below the pump level
QUESTIONA TXV is used to maintain constant: - answer-
Evaporator superheat
, QUESTIONThe chilled water supply to the building is 55 deg F. If
the chiller is being used for human comfort, should you be
concerned about this, and why? - answer-Yes, this temp is too
high for human comfort purposes
QUESTIONThe packing gland of a centrifugal pump serves to: -
answer-The drip part of the packing gland gives evidence that
there is water in the pump
QUESTIONCapacity control of reciprocating hermetic compressor
is typically achieved through: - answer-Operation of the hot gas
bypass valve
QUESTIONThe most important reason to sub-cool the refrigerant
in the condenser is to ensure that: - answer-A pure liquid
refrigerant will enter the metering device
QUESTIONIn order for a refrigerant to become superheated, it
must be heated in a section of the low side refrigerant line: -
answer-Where no liquid refrigerant is present
QUESTIONAll liquid has been recovered from a system to be
overhauled, the system: - answer-Should not be opened until all
vapor has been recovered
QUESTIONWhen a refrigerant engineer uses a portable
compressor recovery unit to remove vapor refrigerant from a
refrigeration system the removal rate of the refrigerant will
gradually slow down because? - answer-The compressor
efficiency is decreasing
QUESTIONYou are the engineer running a 2000-ton (steam
driven turbine) centrifugal refrigeration system, a refrigeration
