FDNY Z51 RMO FINAL
PAPER 2025/2026
QUESTIONS WITH
SOLUTIONS GRADED A+
, 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 ANSWERS-lowering the condenser pressure
In most semi hermetic compressors, the suction vapor is used for - CORRECT
ANSWERS-cools the motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the - CORRECT ANSWERS-difference between the high side and the low side
pressure
the instalation of an inline refrigerant cleaning system is advisable - CORRECT
ANSWERS-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 ANSWERS-a faulty cooling tower
water level controller
when an expansion valve is operating properly, at the end of the evaporator will contain
- CORRECT ANSWERS-only superheated vapor
a centrifugal water pump is considered to be fully primed when - CORRECT
ANSWERS-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 ANSWERS-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 ANSWERS-ammonia
which of the following ashrae refrigerant safety classification is the most toxic -
CORRECT ANSWERS-b3
which of the following ashrae refrigerant safety classification is the most flammable -
CORRECT ANSWERS-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 ANSWERS-r 22
(cooling medium= glycol or any brine solution)
the primary way of achieving capacity control of a an centrifugal compressor is by: -
CORRECT ANSWERS-adjustment to the inlet impeller pre rotation vanes
PAPER 2025/2026
QUESTIONS WITH
SOLUTIONS GRADED A+
, 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 ANSWERS-lowering the condenser pressure
In most semi hermetic compressors, the suction vapor is used for - CORRECT
ANSWERS-cools the motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the - CORRECT ANSWERS-difference between the high side and the low side
pressure
the instalation of an inline refrigerant cleaning system is advisable - CORRECT
ANSWERS-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 ANSWERS-a faulty cooling tower
water level controller
when an expansion valve is operating properly, at the end of the evaporator will contain
- CORRECT ANSWERS-only superheated vapor
a centrifugal water pump is considered to be fully primed when - CORRECT
ANSWERS-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 ANSWERS-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 ANSWERS-ammonia
which of the following ashrae refrigerant safety classification is the most toxic -
CORRECT ANSWERS-b3
which of the following ashrae refrigerant safety classification is the most flammable -
CORRECT ANSWERS-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 ANSWERS-r 22
(cooling medium= glycol or any brine solution)
the primary way of achieving capacity control of a an centrifugal compressor is by: -
CORRECT ANSWERS-adjustment to the inlet impeller pre rotation vanes
