Page | 1
Z-51 REFRIGERATION TEST
Questions and Verified
Answers
Question: 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
Question: The heat removed from the refrigerant in a condenser is:
Ans: Sensible and latent heat
Question: 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
Question: 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
Question: In most semi-hermetic compressors, the suction vapor is used to:
Ans: Cool the motor
Question: 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
Question: The installation of an inline refrigerant cleaning system is advisable:
, Page | 2
Ans: To remove impurities from the system
Question: The type of refrigerant system that is least likely to leak refrigerant into the
building space that are being cooled:
Ans: Indirect system
Question: 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
Question: A superheated vapor is:
Ans: Dry vapor above the saturation temperature
Question: 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
Question: 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
Question: A TXV is used to maintain constant:
Ans: Evaporator superheat
Question: 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
Question: 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
Question: Capacity control of reciprocating hermetic compressor is typically achieved
through:
, Page | 3
Ans: Operation of the hot gas bypass valve
Question: The most important reason to sub-cool the refrigerant in the condenser is to
ensure that:
Ans: A pure liquid refrigerant will enter the metering device
Question: 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
Question: A low side float valve is used to maintain:
Ans: The level of the refrigerant in the evaporator
Question: Regarding fire safety, which ASHRAE refrigerant safety classification indicates
no flammability and lower toxicity?
Ans: A1
Question: When an expansion valve is operating properly, at the end of the evaporator
will contain:
Ans: Only superheated vapor
Question: What information is not contained in a Material Safety Data Sheet?
Ans: Cost of the material
Question: In a steam turbine, what is the function of the Kingsbury thrust bearing?
Ans: Maintain axial positioning of the rotor shaft
Question: A centrifugal water pump is considered to the fully primed when?
Ans: The pump is full of liquid
Question: 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?
Z-51 REFRIGERATION TEST
Questions and Verified
Answers
Question: 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
Question: The heat removed from the refrigerant in a condenser is:
Ans: Sensible and latent heat
Question: 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
Question: 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
Question: In most semi-hermetic compressors, the suction vapor is used to:
Ans: Cool the motor
Question: 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
Question: The installation of an inline refrigerant cleaning system is advisable:
, Page | 2
Ans: To remove impurities from the system
Question: The type of refrigerant system that is least likely to leak refrigerant into the
building space that are being cooled:
Ans: Indirect system
Question: 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
Question: A superheated vapor is:
Ans: Dry vapor above the saturation temperature
Question: 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
Question: 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
Question: A TXV is used to maintain constant:
Ans: Evaporator superheat
Question: 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
Question: 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
Question: Capacity control of reciprocating hermetic compressor is typically achieved
through:
, Page | 3
Ans: Operation of the hot gas bypass valve
Question: The most important reason to sub-cool the refrigerant in the condenser is to
ensure that:
Ans: A pure liquid refrigerant will enter the metering device
Question: 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
Question: A low side float valve is used to maintain:
Ans: The level of the refrigerant in the evaporator
Question: Regarding fire safety, which ASHRAE refrigerant safety classification indicates
no flammability and lower toxicity?
Ans: A1
Question: When an expansion valve is operating properly, at the end of the evaporator
will contain:
Ans: Only superheated vapor
Question: What information is not contained in a Material Safety Data Sheet?
Ans: Cost of the material
Question: In a steam turbine, what is the function of the Kingsbury thrust bearing?
Ans: Maintain axial positioning of the rotor shaft
Question: A centrifugal water pump is considered to the fully primed when?
Ans: The pump is full of liquid
Question: 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?
