Z-51 REFRIGERATION TEST Questions with Detailed Verified Answers

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Z-51 REFRIGERATION TEST
Questions with Detailed 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

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Question: The installation of an inline refrigerant cleaning system is advisable:

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:

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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:

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?

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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?

Ans: Level type tubing bender

Question: A reciprocating compressor is making a knocking sound during
operation. If the refrigerant worn parts are not causing the knocking, what
probably the cause?

Ans: Slugging of the liquid refrigerant

Question: In order for a refrigerant to become superheated, it must be heated
in a section of the low side refrigerant line:

Ans: Where no liquid refrigerant is present

Question: All liquid has been recovered from a system to be overhauled, the
system:

Ans: Should not be opened until all vapor has been recovered

Question: 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?

Ans: The compressor efficiency is decreasing

Question: 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?