1|Page
FDNY Z-51 EXAM NEWEST 2025/2026 ACTUAL EXAM WITH
COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (100%
VERIFIED ANSWERS) |ALREADY GRADED A+| ||PROFESSOR
VERIFIED||
Which of the following best describes house cylinder unloaders
work - ANSWER-Keep in the suction valve opened wall
compressor is in the return stroke
In most semi hermetic compressors the suction valve is used to -
ANSWER-Cool the motor
The amount of refrigerant that flows through the orifices of an
economizer is Determined by the - ANSWER-Difference between
the high side in low side pressure
The installation of an inline refrigerate cleaning system is
Adviseable - ANSWER-To remove impurities from the system
The type of refrigerant system that is least likely to leak refrigerant
into the building space that a being cooled are - ANSWER-An
indirect system
,2|Page
A superheated vapor is - ANSWER-Dry vapor above the
saturation temperature
A Centrifugal water pump is known as a lift pump when the -
ANSWER-The water supply to the pump suction inlet is below the
pump level
A txv is used to maintain constant - ANSWER-Evaporator
superheat
In a steam turbine what is the function of the Kingsbury thrust
bearing - ANSWER-Maintains axial position of the rotor shaft
Copper tubing refrigerant lines must be installed for a new system
it is a well known service practice that tubing collapses At Bendd
that must be made the refrigerant engineer should use -
ANSWER-A lever type tubing Bender
- ANSWER-
, 3|Page
Or reciprocating compressor is making a knocking sound during
operation if parts are not the cause of the knocking - ANSWER-
Slugging of the liquid refrigerant
In order for for drink to become superheated and must be heated
in a section of the low side refrigerant line - ANSWER-Were 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
recovered
What is the function of the turbine auxiliary oil pump - ANSWER-
Establish oil pressure doing turbine start up
The ruptured disk for a low pressure centrifugal refrigeration
machine is normally located on the - ANSWER-Compressor
suction
FDNY Z-51 EXAM NEWEST 2025/2026 ACTUAL EXAM WITH
COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (100%
VERIFIED ANSWERS) |ALREADY GRADED A+| ||PROFESSOR
VERIFIED||
Which of the following best describes house cylinder unloaders
work - ANSWER-Keep in the suction valve opened wall
compressor is in the return stroke
In most semi hermetic compressors the suction valve is used to -
ANSWER-Cool the motor
The amount of refrigerant that flows through the orifices of an
economizer is Determined by the - ANSWER-Difference between
the high side in low side pressure
The installation of an inline refrigerate cleaning system is
Adviseable - ANSWER-To remove impurities from the system
The type of refrigerant system that is least likely to leak refrigerant
into the building space that a being cooled are - ANSWER-An
indirect system
,2|Page
A superheated vapor is - ANSWER-Dry vapor above the
saturation temperature
A Centrifugal water pump is known as a lift pump when the -
ANSWER-The water supply to the pump suction inlet is below the
pump level
A txv is used to maintain constant - ANSWER-Evaporator
superheat
In a steam turbine what is the function of the Kingsbury thrust
bearing - ANSWER-Maintains axial position of the rotor shaft
Copper tubing refrigerant lines must be installed for a new system
it is a well known service practice that tubing collapses At Bendd
that must be made the refrigerant engineer should use -
ANSWER-A lever type tubing Bender
- ANSWER-
, 3|Page
Or reciprocating compressor is making a knocking sound during
operation if parts are not the cause of the knocking - ANSWER-
Slugging of the liquid refrigerant
In order for for drink to become superheated and must be heated
in a section of the low side refrigerant line - ANSWER-Were 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
recovered
What is the function of the turbine auxiliary oil pump - ANSWER-
Establish oil pressure doing turbine start up
The ruptured disk for a low pressure centrifugal refrigeration
machine is normally located on the - ANSWER-Compressor
suction
