FDNY Z51 exam with questions and answers (verified answers graded
FDNY Z-51
A+) latest update 2024/2025
Study online at https://quizlet.com/_bldehg
1. The efficiency of the refrigerant cycle is affected by the Lowering the condenser
operation of the condenser. Of the following, a more ef- pressure
ficient centrifugal compressor operation results from
2. In most semi hermetic compressors, the suction va- Cool's the motor
por is used too
3. The amount of refrigerant that flows through the ori- Difference between the
fices of an economizer is determined by the high side and the low side
pressure
4. the instalation of an inline refrigerant cleaning system to remove impurities from
is advisable the system
5. a refrigerant engineer verifies that a condenser pump a faulty cooling tower wa-
is cavitating of the following the most likely cause for ter level controller
this condition is:
6. when an expansion valve is operating properly, at the only superheated vapor
end of the evaporator will contain
7. a centrifugal water pump is considered to be fully the pump is full of liquid
primed when
8. A refrigeration compressor has failed to turn on. the temperature and pressure
engineer on duty verifies the electrical circuit to the controls
motor, including all switches and circuit breakers is
complete, according to recomended service practice,
the next item to be checked would likely be the:
9. Refrigerants are characterized by their physical prop- ammonia
erties including Flashpoint, refrigeration effect and
, FDNY Z-51
Study online at https://quizlet.com/_bldehg
others, of the refrigerants in commercial and indus-
trial the highest latent heat and refrigerant effect is:
10. which of the following ashrae refrigerant safety clas- B3
sification which is most toxic
11. which of the following ashrae refrigerant safety clas- A3
sification is the most flammable
12. in q indirect refrigeration system,of the following, the r-22 (cooling medium=
one that would not be used as a cooling medium for glycol or any brine solu-
building spaces being cooled is tion)
13. the primary way of achieving capacity control of a an adjustment of the inlet im-
centrifugal compressor is by: peller pre-rotational vanes
14. regarding the functioning of a steam turbine, why is it keeps turbine blades wear
advisable to keep moisture in the inlet low as possible to minimum
15. a water chiller is equipped with a reciprocating com- high suction super heat
pressor, a thermostatic expansion valve and a an air
cooled condenser. A restriction in the refrigerant line
would result in
16. the process by which refrigerant is extracted and recycle
cleaned for reuse without requirements for reclama-
tion is called
17. the purpose of wear rings in a centrifugal pump is to prevent wearing of the
pump housing and im-
peller
18. a centrifugal compressor is in operation with suction 1.39
pressure is 3 psig and the discharge is 10psi what is Ratio= discharge pressure
FDNY Z-51
A+) latest update 2024/2025
Study online at https://quizlet.com/_bldehg
1. The efficiency of the refrigerant cycle is affected by the Lowering the condenser
operation of the condenser. Of the following, a more ef- pressure
ficient centrifugal compressor operation results from
2. In most semi hermetic compressors, the suction va- Cool's the motor
por is used too
3. The amount of refrigerant that flows through the ori- Difference between the
fices of an economizer is determined by the high side and the low side
pressure
4. the instalation of an inline refrigerant cleaning system to remove impurities from
is advisable the system
5. a refrigerant engineer verifies that a condenser pump a faulty cooling tower wa-
is cavitating of the following the most likely cause for ter level controller
this condition is:
6. when an expansion valve is operating properly, at the only superheated vapor
end of the evaporator will contain
7. a centrifugal water pump is considered to be fully the pump is full of liquid
primed when
8. A refrigeration compressor has failed to turn on. the temperature and pressure
engineer on duty verifies the electrical circuit to the controls
motor, including all switches and circuit breakers is
complete, according to recomended service practice,
the next item to be checked would likely be the:
9. Refrigerants are characterized by their physical prop- ammonia
erties including Flashpoint, refrigeration effect and
, FDNY Z-51
Study online at https://quizlet.com/_bldehg
others, of the refrigerants in commercial and indus-
trial the highest latent heat and refrigerant effect is:
10. which of the following ashrae refrigerant safety clas- B3
sification which is most toxic
11. which of the following ashrae refrigerant safety clas- A3
sification is the most flammable
12. in q indirect refrigeration system,of the following, the r-22 (cooling medium=
one that would not be used as a cooling medium for glycol or any brine solu-
building spaces being cooled is tion)
13. the primary way of achieving capacity control of a an adjustment of the inlet im-
centrifugal compressor is by: peller pre-rotational vanes
14. regarding the functioning of a steam turbine, why is it keeps turbine blades wear
advisable to keep moisture in the inlet low as possible to minimum
15. a water chiller is equipped with a reciprocating com- high suction super heat
pressor, a thermostatic expansion valve and a an air
cooled condenser. A restriction in the refrigerant line
would result in
16. the process by which refrigerant is extracted and recycle
cleaned for reuse without requirements for reclama-
tion is called
17. the purpose of wear rings in a centrifugal pump is to prevent wearing of the
pump housing and im-
peller
18. a centrifugal compressor is in operation with suction 1.39
pressure is 3 psig and the discharge is 10psi what is Ratio= discharge pressure
