FDNY Z51 TEST QUESTIONS AND ANSWERS
What is a superheated vapor? - Answers :completely dry vapor
In electrical circuits the conductor is always what color? - Answers :Green or Bare
Unloaders are used for what? - Answers :To increase capacity
Oil foaming in a crankcase is caused by what? - Answers :A sudden drop in crankcase
pressure
How would you test for acid in the refrigerant? - Answers :Spraying liquid refrigerant
from a condenser or receiver on to bond paper
What is the function of a cylinder bypass? - Answers :To allow operation at different
capacities
The chilled water supply to the building is 55F. If the chiller is being used for human
comfort, should you be concerned about this, and why? - Answers :Yes. this
temperature is too high for human comfort purpose
All liquid has been recovered from a system to be overhauled, the system - Answers
:Should not be opened until all vapor has been recovered
When a refrigerant engineer uses a portable compressor recovery unit to remove vapor
refrigerant from a refrigeration system the removal rate of the refrigerant will gradually
slow down because - Answers :The vapor density is decreasing
You are the engineer running a 2000-ton (steam-driven turbine) centrifugal refrigeration
system, a refrigeration system supplies chilled water to a college campus with multiple
buildings. During the course of making your rounds, you check the 9 cell cooling tower
on the roof. You note the water level in all of the cooling tower cells is very low. Which
one of the following immediate action would take? - Answers :Add additional make up
water to cooling tower
A rooftop water cooling tower is connected to a water pump in the building basement
with a 12 inches diameter pipe, with the pump turn off, a pressure gauge at the pumps
inlet show a pressure of 140 PSIG the height of the water column, in feet, would be
closet to. - Answers :323
What device protects the steam turbine from excessive speed? - Answers :Governor
assembly
A refrigeration compressor has failed to turn on. The refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
, is complete according to recommended service practice, the next item to be checked
would likely be the: - Answers :Temperature and pressure controls
Refrigerants are characterized by their physical properties included flashpoint,
refrigeration effect, and others. Of the refrigerants in commercial and industrial the
highest latent heat and refrigerant effect is: - Answers :Ammonia
On what characteristics is ASHRAE refrigerant safety group classification system: -
Answers :flammability and toxicity
Of the following, and example of an in-line refrigerant cleaning system that may be used
with a centrifugal compressor containing R123 refrigerant is: - Answers :Refrigerant
recycling
Information about the physical and chemical properties of a hazardous material can be
found in: - Answers :Material Safety Data Sheet
What is the function of the turbine auxiliary oil pump? - Answers :Establish oil pressure
during turbine start up
The rupture disc for a low-pressure centrifugal refrigeration machine is normally located
on the: - Answers :Compressor suction
What is the primary reason ribbed metal piping is used for electrical wires connected to
the refrigeration system shown below? - Answers :It allows for flexibility and accounts
for vibrations
The most important reason to use at least two compressors in a cascade system is to: -
Answers :Avoid very high compression ratio for each compressor
The suction service valve of a reciprocating compressor is front seated and the
compressor runs until the low pressure cut-out shut the compressor off. When the
machine is stopped, the refrigeration engineer notices that the suction pressure
increase rapidly. The most probable cause of this pressure rise: - Answers :Malfunction
of a compressor valve
Regarding the functioning of a steam turbine, why is it advisable to keep moisture in the
inlet low as possible? - Answers :Keeps turbine blades wear to minimum
According to the attached Material Safety Data Sheet R134 is a - Answers :Clear,
odorless liquid and vapor
Under normal condition, the refrigerant enters the compressor as a: - Answers :Low
pressure superheated vapor and leaves as a high pressure vapor
What is a superheated vapor? - Answers :completely dry vapor
In electrical circuits the conductor is always what color? - Answers :Green or Bare
Unloaders are used for what? - Answers :To increase capacity
Oil foaming in a crankcase is caused by what? - Answers :A sudden drop in crankcase
pressure
How would you test for acid in the refrigerant? - Answers :Spraying liquid refrigerant
from a condenser or receiver on to bond paper
What is the function of a cylinder bypass? - Answers :To allow operation at different
capacities
The chilled water supply to the building is 55F. If the chiller is being used for human
comfort, should you be concerned about this, and why? - Answers :Yes. this
temperature is too high for human comfort purpose
All liquid has been recovered from a system to be overhauled, the system - Answers
:Should not be opened until all vapor has been recovered
When a refrigerant engineer uses a portable compressor recovery unit to remove vapor
refrigerant from a refrigeration system the removal rate of the refrigerant will gradually
slow down because - Answers :The vapor density is decreasing
You are the engineer running a 2000-ton (steam-driven turbine) centrifugal refrigeration
system, a refrigeration system supplies chilled water to a college campus with multiple
buildings. During the course of making your rounds, you check the 9 cell cooling tower
on the roof. You note the water level in all of the cooling tower cells is very low. Which
one of the following immediate action would take? - Answers :Add additional make up
water to cooling tower
A rooftop water cooling tower is connected to a water pump in the building basement
with a 12 inches diameter pipe, with the pump turn off, a pressure gauge at the pumps
inlet show a pressure of 140 PSIG the height of the water column, in feet, would be
closet to. - Answers :323
What device protects the steam turbine from excessive speed? - Answers :Governor
assembly
A refrigeration compressor has failed to turn on. The refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
, is complete according to recommended service practice, the next item to be checked
would likely be the: - Answers :Temperature and pressure controls
Refrigerants are characterized by their physical properties included flashpoint,
refrigeration effect, and others. Of the refrigerants in commercial and industrial the
highest latent heat and refrigerant effect is: - Answers :Ammonia
On what characteristics is ASHRAE refrigerant safety group classification system: -
Answers :flammability and toxicity
Of the following, and example of an in-line refrigerant cleaning system that may be used
with a centrifugal compressor containing R123 refrigerant is: - Answers :Refrigerant
recycling
Information about the physical and chemical properties of a hazardous material can be
found in: - Answers :Material Safety Data Sheet
What is the function of the turbine auxiliary oil pump? - Answers :Establish oil pressure
during turbine start up
The rupture disc for a low-pressure centrifugal refrigeration machine is normally located
on the: - Answers :Compressor suction
What is the primary reason ribbed metal piping is used for electrical wires connected to
the refrigeration system shown below? - Answers :It allows for flexibility and accounts
for vibrations
The most important reason to use at least two compressors in a cascade system is to: -
Answers :Avoid very high compression ratio for each compressor
The suction service valve of a reciprocating compressor is front seated and the
compressor runs until the low pressure cut-out shut the compressor off. When the
machine is stopped, the refrigeration engineer notices that the suction pressure
increase rapidly. The most probable cause of this pressure rise: - Answers :Malfunction
of a compressor valve
Regarding the functioning of a steam turbine, why is it advisable to keep moisture in the
inlet low as possible? - Answers :Keeps turbine blades wear to minimum
According to the attached Material Safety Data Sheet R134 is a - Answers :Clear,
odorless liquid and vapor
Under normal condition, the refrigerant enters the compressor as a: - Answers :Low
pressure superheated vapor and leaves as a high pressure vapor
