fdny z51 written z51 (actual
exam)questions,answers 2024 – 2025
What are pre hot works procedures performed prior to hot works? - ANSWERS-
Check area once a day leading up to hot works
A chilled water system has an air cooled condensing unit on a roof during cold
weather ha what type of protection? - ANSWERS-Air limiting device
What is a compressor safety head? - ANSWERS-A spring on the valve plate
Stand pipe certificate should be available for? - ANSWERS-FDNY and building
inspector
When is a chemical fire extinguisher system needed? - ANSWERS-Where water is
not sufficient
,In most semi hermetic compressors, the suction vapor is used to: - ANSWERS-Cool
the motor
The amount of refrigerant that flows through the orifices of a economizer is
determined by the: - ANSWERS-Difference between the high side and load side
pressure
The installation of an inline refrigerant cleaning system is advisable: - ANSWERS-
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 - ANSWERS-The indirect system
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: - ANSWERS-Lowering the condensing pressure
The heat removed from the refrigerant in a condenser is: - ANSWERS-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: - ANSWERS-Are approved by the US department of
transportation
Which of the following best describes how the cylinder unloader work? -
ANSWERS-Keep in the suction valve opened while the compressor is in the return
stroke
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: - ANSWERS-1.69
A super heated vapor is a ? - ANSWERS-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: - ANSWERS-A faulty cooling
tower water level controller
A centrifugal water pump is known as a lift pump when the: - ANSWERS-The
water supply to the pump suction inlet is below the pump level
A TXV is used to maintain constant: - ANSWERS-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? - ANSWERS-Yes,
this temperature is too high for human comfort purpose
The packing gland of a centrifugal pump serves to: - ANSWERS-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 - ANSWERS-Operation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to
ensure that: - ANSWERS-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. - ANSWERS-An expansion valve that is open to wide
A low side float valve is used to maintain: - ANSWERS-The level of the refrigerant
in the evaporator
Regarding fire safety, which ASHARE refrigerant safety classification indicates no
flammability and lower the toxicity? - ANSWERS-A1
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