FDNY WRITTEN Z51 2026/2027
ACTUAL QUESTIONS WITH
VERIFIED ANSWERS.
What is the state of refrigerant entering the compressor on
a reciprocating machine?
Superheated vapor
What is ammonia's refrigerant ASHRAE classifications?
B2
Why is a pressure relief valve better than a fusible plug?
Minimizes refrigerant loss
Filter driers removes:
Moisture and particles
What is the function of the safety head on a compressor?
Prevents liquid slugging from damaging the valve plate
What does a wiring diagram display?
Wiring of components
A picture of an insulated pump, what is this pump?
Centrifugal chill water pump
If 29.92" HG is equal to 14.7 PSIA, then 26" HG converts to
what in PSIA?
12.77
,You are an engineer running a 2000-ton (steam driven
turbine) centrifugal refrigeration system, a refrigeration
system supplies chilled water to a college campus with
multiple buildings. You are supplying 46 degree chilled
water. All the buildings are satisfied except one building.
What action should the engineer do?
Put an additional chilled water pump online
When charging refrigerant on the low side of a
reciprocating machine with manifold gauges, what is the
position of the manifold?
High side front seated and low side back seated
The cooling medium for a cooling tower is?
Air
When you are finished leak testing with R-22 and nitrogen,
the next step would be?
Vent refrigeration and nitrogen into open air
The charge in a TEV sensing bulb is?
Similar to refrigerant in system
How do you start a centrifugal chiller?
Start the chilled water pump, start the condenser water pump,
check oil, start cooling tower, start compressor
What is the device used to measure the speed of the
turbine?
Tachometer
The condenser pump is on the first floor and not running.
The pressure gauge shows 55 PSI. There is 15 feet for each
floor. What floor is the cooling tower on?
, 8th
There is 7.48 gallons per cubic foot. How many gallons of
water are in a pipe 8 feet in diameter and 10 feet long?
3758
A technician has been asked to estimate the cost of
operating at 5 Hp motor. Because the plant is built by
energy consumed as kilowatt-hours, the technician will
have to calculate the conversion. The equivalent in energy
of a 5 HP motor for 5 hours in kilowatt hours is closest to:
33.6
A standpipe system will be out of service for two days.
How long should there be a fire watch?
The entire time the standpipe is out of service
A circuit breaker has a similar function as what?
A fuse
In the picture below what does the equipment detect?
Refrigerant leaks
If a sprinkler system is offline for two days, how often do
you need to inspect it until it is returned back to service?
Continuously 24 hours a day until system is restored
The only refrigerant/ temperature chart available to a
refrigerant engineer list the temperature is degrees Celsius
if the chart indicates a Celsius temperature of 4 degrees to
equivalent to F:
41 F
Which service valve should be installed to isolate a dual
pressure relief valve while keeping system in service?
ACTUAL QUESTIONS WITH
VERIFIED ANSWERS.
What is the state of refrigerant entering the compressor on
a reciprocating machine?
Superheated vapor
What is ammonia's refrigerant ASHRAE classifications?
B2
Why is a pressure relief valve better than a fusible plug?
Minimizes refrigerant loss
Filter driers removes:
Moisture and particles
What is the function of the safety head on a compressor?
Prevents liquid slugging from damaging the valve plate
What does a wiring diagram display?
Wiring of components
A picture of an insulated pump, what is this pump?
Centrifugal chill water pump
If 29.92" HG is equal to 14.7 PSIA, then 26" HG converts to
what in PSIA?
12.77
,You are an engineer running a 2000-ton (steam driven
turbine) centrifugal refrigeration system, a refrigeration
system supplies chilled water to a college campus with
multiple buildings. You are supplying 46 degree chilled
water. All the buildings are satisfied except one building.
What action should the engineer do?
Put an additional chilled water pump online
When charging refrigerant on the low side of a
reciprocating machine with manifold gauges, what is the
position of the manifold?
High side front seated and low side back seated
The cooling medium for a cooling tower is?
Air
When you are finished leak testing with R-22 and nitrogen,
the next step would be?
Vent refrigeration and nitrogen into open air
The charge in a TEV sensing bulb is?
Similar to refrigerant in system
How do you start a centrifugal chiller?
Start the chilled water pump, start the condenser water pump,
check oil, start cooling tower, start compressor
What is the device used to measure the speed of the
turbine?
Tachometer
The condenser pump is on the first floor and not running.
The pressure gauge shows 55 PSI. There is 15 feet for each
floor. What floor is the cooling tower on?
, 8th
There is 7.48 gallons per cubic foot. How many gallons of
water are in a pipe 8 feet in diameter and 10 feet long?
3758
A technician has been asked to estimate the cost of
operating at 5 Hp motor. Because the plant is built by
energy consumed as kilowatt-hours, the technician will
have to calculate the conversion. The equivalent in energy
of a 5 HP motor for 5 hours in kilowatt hours is closest to:
33.6
A standpipe system will be out of service for two days.
How long should there be a fire watch?
The entire time the standpipe is out of service
A circuit breaker has a similar function as what?
A fuse
In the picture below what does the equipment detect?
Refrigerant leaks
If a sprinkler system is offline for two days, how often do
you need to inspect it until it is returned back to service?
Continuously 24 hours a day until system is restored
The only refrigerant/ temperature chart available to a
refrigerant engineer list the temperature is degrees Celsius
if the chart indicates a Celsius temperature of 4 degrees to
equivalent to F:
41 F
Which service valve should be installed to isolate a dual
pressure relief valve while keeping system in service?
