age 1 of 56
FDNY Z51, Z-51 REFRIGERATION EXAM
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
The 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
The 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
,age 2 of 56
Capacity control of reciprocating hermetic compressor is
typically achieved through: .......Answer.........Operation of the hot
gas bypass valve
The 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
A refrigeration engineer is logging readings from a
reciprocating system. Compressor discharge temperature have
dropped significantly and the suction line pressure is high. Which
of the following that may be causing this set of condition?
.......Answer.........An expansion valve that is open too wide
A low side float valve is used to maintain: .......Answer.........The
level of the refrigerant in the evaporator
,age 3 of 56
The heat removed from the refrigerant in a condenser is:
.......Answer.........Sensible and latent heat
The 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
Which 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
In most semi-hermetic compressors, the suction vapor is used to:
.......Answer.........Cool the motor
, age 4 of 56
The 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
The installation of an inline refrigerant cleaning system is
advisable: .......Answer.........To remove impurities from the system
The type of refrigerant system that is least likely to leak
refrigerant into the building space that are being cooled:
.......Answer.........Indirect system
The 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
A superheated vapor is: .......Answer.........Dry vapor above the
saturation temperature
FDNY Z51, Z-51 REFRIGERATION EXAM
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
The 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
The 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
,age 2 of 56
Capacity control of reciprocating hermetic compressor is
typically achieved through: .......Answer.........Operation of the hot
gas bypass valve
The 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
A refrigeration engineer is logging readings from a
reciprocating system. Compressor discharge temperature have
dropped significantly and the suction line pressure is high. Which
of the following that may be causing this set of condition?
.......Answer.........An expansion valve that is open too wide
A low side float valve is used to maintain: .......Answer.........The
level of the refrigerant in the evaporator
,age 3 of 56
The heat removed from the refrigerant in a condenser is:
.......Answer.........Sensible and latent heat
The 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
Which 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
In most semi-hermetic compressors, the suction vapor is used to:
.......Answer.........Cool the motor
, age 4 of 56
The 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
The installation of an inline refrigerant cleaning system is
advisable: .......Answer.........To remove impurities from the system
The type of refrigerant system that is least likely to leak
refrigerant into the building space that are being cooled:
.......Answer.........Indirect system
The 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
A superheated vapor is: .......Answer.........Dry vapor above the
saturation temperature
