Z-51 REFRIGERATION TEST QUESTIONS
AND ANSWERS 100% VERIFIED.
Efficiency of the refrigerant cycle is affected by the operations of the condenser. Of the
following, a more efficient centrifugal compressor operation results from: - correct
answer. Lowering the condensing pressure
The heat removed from the refrigerant in a condenser is: - correct 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: -
correct answer. Are approved by the US Dept. of Transportation
Which of the following best describes how the cylinder unloader works? - correct
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: - correct answer.
Cool the motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the: - correct answer. Differences between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable: - correct 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: - correct 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: - correct answer. 1.69
A superheated vapor is: - correct answer. Dry vapor above the saturation temperature
,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
AND ANSWERS 100% VERIFIED.
Efficiency of the refrigerant cycle is affected by the operations of the condenser. Of the
following, a more efficient centrifugal compressor operation results from: - correct
answer. Lowering the condensing pressure
The heat removed from the refrigerant in a condenser is: - correct 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: -
correct answer. Are approved by the US Dept. of Transportation
Which of the following best describes how the cylinder unloader works? - correct
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: - correct answer.
Cool the motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the: - correct answer. Differences between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable: - correct 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: - correct 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: - correct answer. 1.69
A superheated vapor is: - correct answer. Dry vapor above the saturation temperature
,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
