Z51 Written UPDATED Exam Questions and CORRECT Answers
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Z51 Written
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Z51 Written
Z51 Written UPDATED Exam Questions
and CORRECT Answers
The efficiency of the refrigerant cycle is affected by the operation of the condenser. of the
following. a more efficient centrifugal compressor operation results from: - Correct AnswerLowering the condensing pressure
The heat removed fr...
Z51 Written UPDATED Exam Questions
and CORRECT Answers
The efficiency of the refrigerant cycle is affected by the operation 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 new York city fire code, you must ensure that the containers: - Correct
Answer- Are approved by the US department of transportation
Which of the following best describes how the cylinder unloader work? - 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 a economizer is determined by
the: - Correct Answer- Difference between the high side and load 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 cooled - Correct Answer- The indirect system
The suction pressure of a reciprocating compressor is 65PSIG. the discharge pressure of this
compressor is 120PSIG. the atmospheric is 14.7 PSI. the compression ratio for the given
condition is closet to: - Correct Answer- 1.69
A super heated vapor is a ? - 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 55F. if the chiller is being used for human comfort,
should you be concerned about this , and why? - Correct Answer- Yes, this temperature is too
high for human comfort purpose
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 a 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 reading 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 to wide
A low side float valve is used to maintain: - Correct Answer- The level of the refrigerant in
the evaporator
Regarding fire safety, which ASHARE refrigerant safety classification indicates no
flammability and lower the 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-MSDS? - Correct Answer-
Cost of 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 be 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- Lever type tubing bender
A reciprocating compressor is making a knocking sound during operation. if the refrigerant
worn parts are not causing the knocking, what is probably the cause - Correct Answer- The
slugging of the liquid refrigerant
In order for a refrigerant to become superheated in a section of the lowside 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 removed
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 vapor density 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 action would take? - Correct Answer- Add additional make up water
to cooling tower
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