FDNY Z51 WRITTEN EXAM ACTUAL EXAM 2
VERSIONS (VERSION A AND B) WITH DETAILED
VERIFIED ANSWERS || ALREADY 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
ANSWER Lowering the condenser pressure
In most semi hermetic compressors, the suction vapor is used too -CORRECT
ANSWER Cool's 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 cavitating 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 which is 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 of the inlet impeller pre-rotational 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
Ratio= discharge pressure ((PSIA ÷ Sucction Pressure
PSIA÷ PSIA
electrical current is measured in -CORRECT ANSWER amperes
how would you put an additional pump online -CORRECT ANSWER open suction
valve, open discharge valve gradually
of the following, the major advantage of a shell and coil condenser is -CORRECT
ANSWER there is less danger of developing leaks
an engineer needs to vary the flow of refrigerant in a refrigeration system, which
operation in the flow of the system does not include -CORRECT ANSWER solenoid
valve
thermal bull is attached to the suction plate between the evaporator cokl and the
compressor by an insulated line. assume that the machine room is 85° F. a break down
of the insulation results in: -CORRECT ANSWER flooding of the evaporator
water and moisture is serious problem in a refrigerant system how to avoid -CORRECT
ANSWER proper evaluation at the charging of the system
VERSIONS (VERSION A AND B) WITH DETAILED
VERIFIED ANSWERS || ALREADY 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
ANSWER Lowering the condenser pressure
In most semi hermetic compressors, the suction vapor is used too -CORRECT
ANSWER Cool's 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 cavitating 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 which is 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 of the inlet impeller pre-rotational 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
Ratio= discharge pressure ((PSIA ÷ Sucction Pressure
PSIA÷ PSIA
electrical current is measured in -CORRECT ANSWER amperes
how would you put an additional pump online -CORRECT ANSWER open suction
valve, open discharge valve gradually
of the following, the major advantage of a shell and coil condenser is -CORRECT
ANSWER there is less danger of developing leaks
an engineer needs to vary the flow of refrigerant in a refrigeration system, which
operation in the flow of the system does not include -CORRECT ANSWER solenoid
valve
thermal bull is attached to the suction plate between the evaporator cokl and the
compressor by an insulated line. assume that the machine room is 85° F. a break down
of the insulation results in: -CORRECT ANSWER flooding of the evaporator
water and moisture is serious problem in a refrigerant system how to avoid -CORRECT
ANSWER proper evaluation at the charging of the system
