Z-51 REFRIGERATION TEST With Correct Solutions
2024 Update
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 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
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
A 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
A 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
A TXV is used to maintain constant: - 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? - 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
, 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
Regarding fire safety, which ASHRAE refrigerant safety classification indicates no flammability and lower
toxicity? - Answer -A1
When an expansion valve is operating properly, at the end of the evaporator will contain: - Answer -Only
superheated vapor
What information is not contained in a Material Safety Data Sheet? - Answer -Cost of the material
In a steam turbine, what is the function of the Kingsbury thrust bearing? - Answer -Maintain axial
positioning of the rotor shaft
A centrifugal water pump is considered to the fully primed when? - 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? - 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? - 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: - Answer -Where no liquid refrigerant is present
All liquid has been recovered from a system to be overhauled, the system: - 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? - 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? - Answer -
Add additional make up water to the cooling tower
2024 Update
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 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
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
A 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
A 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
A TXV is used to maintain constant: - 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? - 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
, 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
Regarding fire safety, which ASHRAE refrigerant safety classification indicates no flammability and lower
toxicity? - Answer -A1
When an expansion valve is operating properly, at the end of the evaporator will contain: - Answer -Only
superheated vapor
What information is not contained in a Material Safety Data Sheet? - Answer -Cost of the material
In a steam turbine, what is the function of the Kingsbury thrust bearing? - Answer -Maintain axial
positioning of the rotor shaft
A centrifugal water pump is considered to the fully primed when? - 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? - 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? - 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: - Answer -Where no liquid refrigerant is present
All liquid has been recovered from a system to be overhauled, the system: - 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? - 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? - Answer -
Add additional make up water to the cooling tower
