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Z-51 REFRIGERATION TEST Questions and
Answers (Expert Solutions)
Q: Efficiency of the refrigerant cycle is affected by the operations of the condenser. Of
the following, a more efficient centrifugal compressor operation results from:
ANS 🗹🗹: Lowering the condensing pressure
Q: The heat removed from the refrigerant in a condenser is:
ANS 🗹🗹: Sensible and latent heat
Q: 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:
ANS 🗹🗹: Are approved by the US Dept. of Transportation
Q: Which of the following best describes how the cylinder unloader works?
ANS 🗹🗹: Keep in the suction valve opened while the compressor is in the return
stroke
Q: In most semi-hermetic compressors, the suction vapor is used to:
ANS 🗹🗹: Cool the motor
Q: The amount of refrigerant that flows through the orifices of an economizer is
determined by the:
ANS 🗹🗹: Differences between the high side and low side pressure
Q: The installation of an inline refrigerant cleaning system is advisable:
ANS 🗹🗹: To remove impurities from the system
Q: The type of refrigerant system that is least likely to leak refrigerant into the building
space that are being cooled:
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ANS 🗹🗹: Indirect system
Q: 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:
ANS 🗹🗹: 1.69
Q: A superheated vapor is:
ANS 🗹🗹: Dry vapor above the saturation temperature
Q: A refrigerant engineer verifies that a condenser water pump is cavitating. Of the
following, the most likely cause for this condition is:
ANS 🗹🗹: A faulty cooling tower water level controller
Q: A centrifugal water pump is known as a lift pump when the:
ANS 🗹🗹: The water supply to the pump suction inlet is below the pump level
Q: A TXV is used to maintain constant:
ANS 🗹🗹: Evaporator superheat
Q: 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?
ANS 🗹🗹: Yes, this temp is too high for human comfort purposes
Q: The packing gland of a centrifugal pump serves to:
ANS 🗹🗹: The drip part of the packing gland gives evidence that there is water in
the pump
Q: Capacity control of reciprocating hermetic compressor is typically achieved through:
ANS 🗹🗹: Operation of the hot gas bypass valve
Q: The most important reason to sub-cool the refrigerant in the condenser is to ensure
that:
, Page | 3
ANS 🗹🗹: A pure liquid refrigerant will enter the metering device
Q: 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?
ANS 🗹🗹: An expansion valve that is open too wide
Q: A low side float valve is used to maintain:
ANS 🗹🗹: The level of the refrigerant in the evaporator
Q: Regarding fire safety, which ASHRAE refrigerant safety classification indicates no
flammability and lower toxicity?
ANS 🗹🗹: A1
Q: When an expansion valve is operating properly, at the end of the evaporator will
contain:
ANS 🗹🗹: Only superheated vapor
Q: What information is not contained in a Material Safety Data Sheet?
ANS 🗹🗹: Cost of the material
Q: In a steam turbine, what is the function of the Kingsbury thrust bearing?
ANS 🗹🗹: Maintain axial positioning of the rotor shaft
Q: A centrifugal water pump is considered to the fully primed when?
ANS 🗹🗹: The pump is full of liquid
Q: 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?
ANS 🗹🗹: Level type tubing bender
Q: A reciprocating compressor is making a knocking sound during operation. If the
refrigerant worn parts are not causing the knocking, what probably the cause?
Z-51 REFRIGERATION TEST Questions and
Answers (Expert Solutions)
Q: Efficiency of the refrigerant cycle is affected by the operations of the condenser. Of
the following, a more efficient centrifugal compressor operation results from:
ANS 🗹🗹: Lowering the condensing pressure
Q: The heat removed from the refrigerant in a condenser is:
ANS 🗹🗹: Sensible and latent heat
Q: 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:
ANS 🗹🗹: Are approved by the US Dept. of Transportation
Q: Which of the following best describes how the cylinder unloader works?
ANS 🗹🗹: Keep in the suction valve opened while the compressor is in the return
stroke
Q: In most semi-hermetic compressors, the suction vapor is used to:
ANS 🗹🗹: Cool the motor
Q: The amount of refrigerant that flows through the orifices of an economizer is
determined by the:
ANS 🗹🗹: Differences between the high side and low side pressure
Q: The installation of an inline refrigerant cleaning system is advisable:
ANS 🗹🗹: To remove impurities from the system
Q: The type of refrigerant system that is least likely to leak refrigerant into the building
space that are being cooled:
, Page | 2
ANS 🗹🗹: Indirect system
Q: 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:
ANS 🗹🗹: 1.69
Q: A superheated vapor is:
ANS 🗹🗹: Dry vapor above the saturation temperature
Q: A refrigerant engineer verifies that a condenser water pump is cavitating. Of the
following, the most likely cause for this condition is:
ANS 🗹🗹: A faulty cooling tower water level controller
Q: A centrifugal water pump is known as a lift pump when the:
ANS 🗹🗹: The water supply to the pump suction inlet is below the pump level
Q: A TXV is used to maintain constant:
ANS 🗹🗹: Evaporator superheat
Q: 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?
ANS 🗹🗹: Yes, this temp is too high for human comfort purposes
Q: The packing gland of a centrifugal pump serves to:
ANS 🗹🗹: The drip part of the packing gland gives evidence that there is water in
the pump
Q: Capacity control of reciprocating hermetic compressor is typically achieved through:
ANS 🗹🗹: Operation of the hot gas bypass valve
Q: The most important reason to sub-cool the refrigerant in the condenser is to ensure
that:
, Page | 3
ANS 🗹🗹: A pure liquid refrigerant will enter the metering device
Q: 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?
ANS 🗹🗹: An expansion valve that is open too wide
Q: A low side float valve is used to maintain:
ANS 🗹🗹: The level of the refrigerant in the evaporator
Q: Regarding fire safety, which ASHRAE refrigerant safety classification indicates no
flammability and lower toxicity?
ANS 🗹🗹: A1
Q: When an expansion valve is operating properly, at the end of the evaporator will
contain:
ANS 🗹🗹: Only superheated vapor
Q: What information is not contained in a Material Safety Data Sheet?
ANS 🗹🗹: Cost of the material
Q: In a steam turbine, what is the function of the Kingsbury thrust bearing?
ANS 🗹🗹: Maintain axial positioning of the rotor shaft
Q: A centrifugal water pump is considered to the fully primed when?
ANS 🗹🗹: The pump is full of liquid
Q: 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?
ANS 🗹🗹: Level type tubing bender
Q: A reciprocating compressor is making a knocking sound during operation. If the
refrigerant worn parts are not causing the knocking, what probably the cause?
