FDNY Z51 WRITTEN EXAM ACTUAL EXAM 2
VERSIONS (VERSION 1AND 2) COMPLETE 400
QUESTIONS WITH DETAILED VERIFIED ANSWERS /
ALREADY GRADED A+
VERSION 1
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: -
ANSWERLowering the condensing pressure
The heat removed from the refrigerant in a condenser is: - ANSWERSensible 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: - ANSWERAre approved by the US department of transportation
Which of the following best describes how the cylinder unloader work? - ANSWERKeep
in the suction valve opened while the compressor is in the return stroke
In most semi hermetic compressors, the suction vapor is used to: - ANSWERCool the
motor
The amount of refrigerant that flows through the orifices of a economizer is determined
by the: - ANSWERDifference between the high side and load side pressure
The installation of an inline refrigerant cleaning system is advisable: - ANSWERTo
remove impurities from the system
The type of refrigerant system that is least likely to leak refrigerant into the building
space that are cooled - ANSWERThe 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: - ANSWER1.69
A super heated vapor is a ? - ANSWERDry 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: - ANSWERA faulty cooling tower
water level controller
A centrifugal water pump is known as a lift pump when the: - ANSWERThe water supply
to the pump suction inlet is below the pump level
A TXV is used to maintain constant: - ANSWEREvaporator 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? - ANSWERYes, this
temperature is too high for human comfort purpose
The packing gland of a centrifugal pump serves to: - ANSWERThe 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 -
ANSWEROperation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that:
- ANSWERA 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. - ANSWERAn
expansion valve that is open to wide
A low side float valve is used to maintain: - ANSWERThe level of the refrigerant in the
evaporator
Regarding fire safety, which ASHARE refrigerant safety classification indicates no
flammability and lower the toxicity? - ANSWERA1
When an expansion valve is operating properly, at the end of the evaporator will
contain: - ANSWEROnly superheated vapor
What information is not contained in a material safety data sheet-MSDS? -
ANSWERCost of material
In a steam turbine, what is the function of the kingsbury thrust bearing -
ANSWERMaintain axial positioning of the rotor shaft
A centrifugal water pump is considered to be fully primed when - ANSWERThe 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 - ANSWERLever 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 -
ANSWERThe slugging of the liquid refrigerant
In order for a refrigerant to become superheated in a section of the lowside refrigerant
line: - ANSWERWhere no liquid refrigerant is present
All liquid has been recovered from a system to be overhauled, the system -
ANSWERShould 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 - ANSWERThe 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? - ANSWERAdd additional make up
water to cooling tower
A rooftop water cooling tower is connected to a water pump in the building basement
with a 12 inches diameter pipe. with the pump turn off, a pressure gauge at the pumps
inlet show a pressure of 140 PSIG the height of the water column, in feet, would be
closet to. - ANSWER323
What device protects the steam turbine from excessive speed? - ANSWERgovernor
assembly
A refrigeration compressor has failed to turn on. the refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
is complete according to recommended service practice, the next item to be checked
would likely be the: - ANSWERTemperature and pressure controls
Refrigerants are characterized by their physical properties included flash point,
refrigeration effect, and others. of the refrigerant in commercial and industrial the
highest latent hear and refrigerant effect is: - ANSWERAmmonia
On what characteristics is ASHRAE refrigerant safety group classification system: -
ANSWERFlammability and toxicity
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