FDNY Z51 STUDY GUIDE UPDATED 2024-
2026WITH ALL 120 QUESTIONS AND 100%
CORRECT ANSWER/ FDNY Z51 EXAM
UPDATED VERSION
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 condenser
pressure
In most semi hermetic compressors, the suction vapor is used for -
CORRECT ANSWER ✔️cools the motor
The amount of refrigerant that flows through the orifices of an economizer
is determined by the -CORRECT ANSWER ✔️difference between the high
side and the low side pressure
the instalation of an inline refrigerant cleaning system is advisable -
CORRECT ANSWER ✔️to remove impurities from the system
a refrigerant engineer verifies that a condenser pump is cavitation of the
following the most likely cause for this condition is: -CORRECT ANSWER
✔️a faulty cooling tower water level controller
,when an expansion valve is operating properly, at the end of the evaporator
will contain -CORRECT ANSWER ✔️only superheated vapor
a centrifugal water pump is considered to be fully primed when -CORRECT
ANSWER ✔️the pump is full of liquid
A refrigeration compressor has failed to turn on. the engineer on duty
verifies the electrical circuit to the motor, including all switches and circuit
breakers is complete, according to recomended service practice, the next
item to be checked would likely be the: -CORRECT ANSWER
✔️temperature and pressure controls
Refrigerants are characterized by their physical properties including
Flashpoint, refrigeration effect and others, of the refrigerants in commercial
and industrial the highest latent heat and refrigerant effect is: -CORRECT
ANSWER ✔️ammonia
which of the following ashrae refrigerant safety classification is the most
toxic -CORRECT ANSWER ✔️b3
which of the following ashrae refrigerant safety classification is the most
flammable -CORRECT ANSWER ✔️a3
in q indirect refrigeration system,of the following, the one that would not be
used as a cooling medium for building spaces being cooled is -CORRECT
ANSWER ✔️r 22 (cooling medium= glycol or any brine solution)
, the primary way of achieving capacity control of a an centrifugal
compressor is by: -CORRECT ANSWER ✔️adjustment to the inlet impeller
pre rotation vanes
regarding the functioning of a steam turbine, why is it advisable to keep
moisture in the inlet low as possible -CORRECT ANSWER ✔️keeps
turbine blades wear to minimum
a water chiller is equipped with a reciprocating compressor, a thermostatic
expansion valve and a an air cooled condenser. A restriction in the
refrigerant line would result in -CORRECT ANSWER ✔️high suction super
heat
the process by which refrigerant is extracted and cleaned for reuse without
requirements for reclamation is called -CORRECT ANSWER ✔️recycle
the purpose of wear rings in a centrifugal pump is to -CORRECT ANSWER
✔️prevent wearing of the pump housing and impeller
a centrifugal compressor is in operation with suction pressure is 3 psig and
the discharge is 10psi what is the atmospheric pressure is 14.7 which is the
ratio closest to -CORRECT ANSWER ✔️1.39
electrical current us measured in -CORRECT ANSWER ✔️amperage
2026WITH ALL 120 QUESTIONS AND 100%
CORRECT ANSWER/ FDNY Z51 EXAM
UPDATED VERSION
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 condenser
pressure
In most semi hermetic compressors, the suction vapor is used for -
CORRECT ANSWER ✔️cools the motor
The amount of refrigerant that flows through the orifices of an economizer
is determined by the -CORRECT ANSWER ✔️difference between the high
side and the low side pressure
the instalation of an inline refrigerant cleaning system is advisable -
CORRECT ANSWER ✔️to remove impurities from the system
a refrigerant engineer verifies that a condenser pump is cavitation of the
following the most likely cause for this condition is: -CORRECT ANSWER
✔️a faulty cooling tower water level controller
,when an expansion valve is operating properly, at the end of the evaporator
will contain -CORRECT ANSWER ✔️only superheated vapor
a centrifugal water pump is considered to be fully primed when -CORRECT
ANSWER ✔️the pump is full of liquid
A refrigeration compressor has failed to turn on. the engineer on duty
verifies the electrical circuit to the motor, including all switches and circuit
breakers is complete, according to recomended service practice, the next
item to be checked would likely be the: -CORRECT ANSWER
✔️temperature and pressure controls
Refrigerants are characterized by their physical properties including
Flashpoint, refrigeration effect and others, of the refrigerants in commercial
and industrial the highest latent heat and refrigerant effect is: -CORRECT
ANSWER ✔️ammonia
which of the following ashrae refrigerant safety classification is the most
toxic -CORRECT ANSWER ✔️b3
which of the following ashrae refrigerant safety classification is the most
flammable -CORRECT ANSWER ✔️a3
in q indirect refrigeration system,of the following, the one that would not be
used as a cooling medium for building spaces being cooled is -CORRECT
ANSWER ✔️r 22 (cooling medium= glycol or any brine solution)
, the primary way of achieving capacity control of a an centrifugal
compressor is by: -CORRECT ANSWER ✔️adjustment to the inlet impeller
pre rotation vanes
regarding the functioning of a steam turbine, why is it advisable to keep
moisture in the inlet low as possible -CORRECT ANSWER ✔️keeps
turbine blades wear to minimum
a water chiller is equipped with a reciprocating compressor, a thermostatic
expansion valve and a an air cooled condenser. A restriction in the
refrigerant line would result in -CORRECT ANSWER ✔️high suction super
heat
the process by which refrigerant is extracted and cleaned for reuse without
requirements for reclamation is called -CORRECT ANSWER ✔️recycle
the purpose of wear rings in a centrifugal pump is to -CORRECT ANSWER
✔️prevent wearing of the pump housing and impeller
a centrifugal compressor is in operation with suction pressure is 3 psig and
the discharge is 10psi what is the atmospheric pressure is 14.7 which is the
ratio closest to -CORRECT ANSWER ✔️1.39
electrical current us measured in -CORRECT ANSWER ✔️amperage
