Z-51 REFRIGERATION TEST UPDATED
ACTUAL Exam Questions and CORRECT
Answers
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
ACTUAL Exam Questions and CORRECT
Answers
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
