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FDNY Z51 EXAM 2024 WITH 350+ REAL EXAM
QUESTIONS AND 100% CORRECT ANSWERS
GRADED A/ REAL FDNY Z -51 EXAM 2024/2025
LATEST VERSION(BRAND NEW!!)
What happens when a steam turbine reaches critical speed? - ANSWER-Turbine will vibrate violently
In a steam turbine, what is the function of the kingsbury thrust bearing - ANSWER-Maintain axial positioning of the rotor shaft
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: - ANSWER-Lowering the condensing pressure
A centrifugal water pump is considered to be fully primed when - ANSWER-The pump is full of liquid
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: - ANSWER-Are approved by the US department of transportation
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 - ANSWER-Lever type tubing bender
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pg. 2 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 - ANSWER-The slugging of the liquid refrigerant
In order for a refrigerant to become superheated in a section of the lowside
refrigerant line: - ANSWER-Where no liquid refrigerant is present
All liquid has been recovered from a system to be overhauled, the system - 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 - 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? - ANSWER-Add 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. - ANSWER-323
The heat removed from the refrigerant in a condenser is: - ANSWER-Sensible and
latent heat
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pg. 3 Which of the following best describes how the cylinder unloader work? - 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: - ANSWER-Cool
the motor
The amount of refrigerant that flows through the orifices of a economizer is
determined by the: - ANSWER-Difference between the high side and load side
pressure
The installation of an inline refrigerant cleaning system is advisable: - 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 - 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: - ANSWER-1.69
A super heated vapor is a ? - 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: - ANSWER-A faulty cooling tower water level controller
A centrifugal water pump is known as a lift pump when the: - ANSWER-The
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A TXV is used to maintain constant: - 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? - ANSWER-Yes, this temperature is too high for human comfort purpose
The packing gland of a centrifugal pump serves to: - 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 - ANSWER-Operation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure
that: - 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. - ANSWER-An expansion valve that is open to wide
A low side float valve is used to maintain: - ANSWER-The level of the refrigerant in the evaporator
Regarding fire safety, which ASHARE refrigerant safety classification indicates no flammability and lower the toxicity? - ANSWER-A1
When an expansion valve is operating properly, at the end of the evaporator will
contain: - ANSWER-Only superheated vapor
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