FDNY Z51/ Z-51 REFRIGERATION EXAM TEST2024-2026 ACTUAL EXAM
250 QUESTIONS AND CORRECT DETAILED ANSWERS |ALREADY
GRADED A+
A refrigerant engineer verifies that a condenser water pump is cavitating. Of the
following, the most likely cause for this condition is: - CORRECT ANSWER✔✔A faulty
cooling tower water level controller
A centrifugal water pump is known as a lift pump when the: - CORRECT ANSWER✔✔
The water supply to the pump suction inlet is below the pump level
A TXV is used to maintain constant: - CORRECT ANSWER✔✔Evaporator superheat
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? - CORRECT ANSWER
✔✔Yes, this temp is too high for human comfort purposes
The packing gland of a centrifugal pump serves to: - CORRECT ANSWER✔✔The drip
part of the packing gland gives evidence that there is water in the pump
Capacity control of reciprocating hermetic compressor is typically achieved through: -
CORRECT ANSWER✔✔Operation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that:
- CORRECT 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? - CORRECT ANSWER
✔✔An expansion valve that is open too wide
A low side float valve is used to maintain: - CORRECT ANSWER✔✔The level of the
refrigerant in the evaporator
Regarding fire safety, which ASHRAE refrigerant safety classification indicates no
flammability and lower toxicity? - CORRECT ANSWER✔✔A1
When an expansion valve is operating properly, at the end of the evaporator will
contain: - CORRECT ANSWER✔✔Only superheated vapor
,What information is not contained in a Material Safety Data Sheet? - CORRECT
ANSWER✔✔Cost of the material
In a steam turbine, what is the function of the Kingsbury thrust bearing? - CORRECT
ANSWER✔✔Maintain axial positioning of the rotor shaft
A centrifugal water pump is considered to the fully primed when? - CORRECT
ANSWER✔✔The pump is full of liquid
Copper tubing refrigerant lines must be installed for a new system. It is a well known
service practice that tubing collapses at bends that must be made, the refrigerant
engineer should use? - CORRECT ANSWER✔✔Level type tubing bender
A reciprocating compressor is making a knocking sound during operation. If the
refrigerant worn parts are not causing the knocking, what probably the cause? -
CORRECT ANSWER✔✔Slugging of the liquid refrigerant
In order for a refrigerant to become superheated, it must be heated in a section of the
low side refrigerant line: - CORRECT ANSWER✔✔Where no liquid refrigerant is
present
All liquid has been recovered from a system to be overhauled, the system: - CORRECT
ANSWER✔✔Should not be opened until all vapor has been recovered
When 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? - CORRECT ANSWER✔✔The compressor efficiency is
decreasing
You are the engineer running a 2000-ton (steam driven turbine) centrifugal refrigeration
system, a refrigeration system supplies chilled water to a college campus with multiple
buildings. During the course of making your rounds, you check the 9 cell cooling tower
on the roof. You note the water level in all of the cooling tower cells is very low. Which
one of the following immediate actions would take? - CORRECT ANSWER✔✔Add
additional make up water to the cooling tower
A rooftop water cooling tower is connected to a water pump in the building basement
with a 12 inch diameter pipe. With the pipe turned off, a pressure gauge at the pumps
inlet show a pressure of 140 PSIG the height of the water column, in feet, would be
closest to: - CORRECT ANSWER✔✔323
What device protects the steam turbine from excessive speed? - CORRECT ANSWER
✔✔Governor assembly
, A refrigeration compressor has failed to turn on. The refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
is complete according to recommended service practice, the next item to be checked
would likely be the: - CORRECT ANSWER✔✔Temperature and pressure controls
Refrigerants are characterized by their physical properties included flashpoint,
refrigeration effect, and others. Of the refrigerants in commercial and industrial, the one
with the highest latent heat and refrigerant effect is: - CORRECT ANSWER✔✔
Ammonia
Of what characteristics is ASHRAE refrigerant safety group classification system: -
CORRECT ANSWER✔✔Flammability and toxicity
Of the following, an example of an in line refrigerant cleaning system that may be used
with a centrifugal compressor containing R-123 refrigerant is: - CORRECT ANSWER✔
✔Recycling
Information about the physical and chemical properties of a hazardous material can be
found in: - CORRECT ANSWER✔✔Material Safety Data Sheet
What is the function of the turbine auxiliary oil pump? - CORRECT ANSWER✔✔
Establish oil pressure during turbine start up
The rupture disc for a low pressure centrifugal refrigeration machine is normally located
on the: - CORRECT ANSWER✔✔Compressor suction
What is the primary reason ribbed metal piping is used for electrical wires connected to
the refrigeration system shown below? - CORRECT ANSWER✔✔It allows for flexibility
and accounts for vibrations
A multi cylinder reciprocating compressor uses cylinder unloaders to regulate capacity,
what would not occur if some of the unloaders fail to operate when needed? -
CORRECT ANSWER✔✔The chill water temperature will increase
As shown in the picture below, the suction gauge of a condenser water pump reads 55
PSI. The pipe supplying the pump is 75 feet long and 12 inches in diameter.
Approximately, how many gallons of water do you expect to obtain if the pipe is drained
completely? - CORRECT ANSWER✔✔440
A water chiller system uses refrigerant R-123. A leak in the evaporator shell may result
in: - CORRECT ANSWER✔✔A higher than normal high side pressure
Capacitors are used on refrigeration motors. Of the following, the function of these
devices is to: - CORRECT ANSWER✔✔Store electrical chargers during starting and
running the motor
250 QUESTIONS AND CORRECT DETAILED ANSWERS |ALREADY
GRADED A+
A refrigerant engineer verifies that a condenser water pump is cavitating. Of the
following, the most likely cause for this condition is: - CORRECT ANSWER✔✔A faulty
cooling tower water level controller
A centrifugal water pump is known as a lift pump when the: - CORRECT ANSWER✔✔
The water supply to the pump suction inlet is below the pump level
A TXV is used to maintain constant: - CORRECT ANSWER✔✔Evaporator superheat
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? - CORRECT ANSWER
✔✔Yes, this temp is too high for human comfort purposes
The packing gland of a centrifugal pump serves to: - CORRECT ANSWER✔✔The drip
part of the packing gland gives evidence that there is water in the pump
Capacity control of reciprocating hermetic compressor is typically achieved through: -
CORRECT ANSWER✔✔Operation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that:
- CORRECT 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? - CORRECT ANSWER
✔✔An expansion valve that is open too wide
A low side float valve is used to maintain: - CORRECT ANSWER✔✔The level of the
refrigerant in the evaporator
Regarding fire safety, which ASHRAE refrigerant safety classification indicates no
flammability and lower toxicity? - CORRECT ANSWER✔✔A1
When an expansion valve is operating properly, at the end of the evaporator will
contain: - CORRECT ANSWER✔✔Only superheated vapor
,What information is not contained in a Material Safety Data Sheet? - CORRECT
ANSWER✔✔Cost of the material
In a steam turbine, what is the function of the Kingsbury thrust bearing? - CORRECT
ANSWER✔✔Maintain axial positioning of the rotor shaft
A centrifugal water pump is considered to the fully primed when? - CORRECT
ANSWER✔✔The pump is full of liquid
Copper tubing refrigerant lines must be installed for a new system. It is a well known
service practice that tubing collapses at bends that must be made, the refrigerant
engineer should use? - CORRECT ANSWER✔✔Level type tubing bender
A reciprocating compressor is making a knocking sound during operation. If the
refrigerant worn parts are not causing the knocking, what probably the cause? -
CORRECT ANSWER✔✔Slugging of the liquid refrigerant
In order for a refrigerant to become superheated, it must be heated in a section of the
low side refrigerant line: - CORRECT ANSWER✔✔Where no liquid refrigerant is
present
All liquid has been recovered from a system to be overhauled, the system: - CORRECT
ANSWER✔✔Should not be opened until all vapor has been recovered
When 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? - CORRECT ANSWER✔✔The compressor efficiency is
decreasing
You are the engineer running a 2000-ton (steam driven turbine) centrifugal refrigeration
system, a refrigeration system supplies chilled water to a college campus with multiple
buildings. During the course of making your rounds, you check the 9 cell cooling tower
on the roof. You note the water level in all of the cooling tower cells is very low. Which
one of the following immediate actions would take? - CORRECT ANSWER✔✔Add
additional make up water to the cooling tower
A rooftop water cooling tower is connected to a water pump in the building basement
with a 12 inch diameter pipe. With the pipe turned off, a pressure gauge at the pumps
inlet show a pressure of 140 PSIG the height of the water column, in feet, would be
closest to: - CORRECT ANSWER✔✔323
What device protects the steam turbine from excessive speed? - CORRECT ANSWER
✔✔Governor assembly
, A refrigeration compressor has failed to turn on. The refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
is complete according to recommended service practice, the next item to be checked
would likely be the: - CORRECT ANSWER✔✔Temperature and pressure controls
Refrigerants are characterized by their physical properties included flashpoint,
refrigeration effect, and others. Of the refrigerants in commercial and industrial, the one
with the highest latent heat and refrigerant effect is: - CORRECT ANSWER✔✔
Ammonia
Of what characteristics is ASHRAE refrigerant safety group classification system: -
CORRECT ANSWER✔✔Flammability and toxicity
Of the following, an example of an in line refrigerant cleaning system that may be used
with a centrifugal compressor containing R-123 refrigerant is: - CORRECT ANSWER✔
✔Recycling
Information about the physical and chemical properties of a hazardous material can be
found in: - CORRECT ANSWER✔✔Material Safety Data Sheet
What is the function of the turbine auxiliary oil pump? - CORRECT ANSWER✔✔
Establish oil pressure during turbine start up
The rupture disc for a low pressure centrifugal refrigeration machine is normally located
on the: - CORRECT ANSWER✔✔Compressor suction
What is the primary reason ribbed metal piping is used for electrical wires connected to
the refrigeration system shown below? - CORRECT ANSWER✔✔It allows for flexibility
and accounts for vibrations
A multi cylinder reciprocating compressor uses cylinder unloaders to regulate capacity,
what would not occur if some of the unloaders fail to operate when needed? -
CORRECT ANSWER✔✔The chill water temperature will increase
As shown in the picture below, the suction gauge of a condenser water pump reads 55
PSI. The pipe supplying the pump is 75 feet long and 12 inches in diameter.
Approximately, how many gallons of water do you expect to obtain if the pipe is drained
completely? - CORRECT ANSWER✔✔440
A water chiller system uses refrigerant R-123. A leak in the evaporator shell may result
in: - CORRECT ANSWER✔✔A higher than normal high side pressure
Capacitors are used on refrigeration motors. Of the following, the function of these
devices is to: - CORRECT ANSWER✔✔Store electrical chargers during starting and
running the motor
