FDNY Z51 REFRIGERATION EXAM 2
2024-2025 WITH ACTUAL CORRECT
QUESTIONS AND VERIFIED
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A motor winding is touching the inside of the motor housing. This could result in:
Shock may occur to personnel
An engineer suspects a short of the motor winding have caused the motor to trip on overload. The
engineer should use what instrument to check the motor:
Ohmmeter
An engineer would expect a relief valve to start function at a pressure:
Design pressure
How many BTU's are removed in a 30 ton system?
360,000 BTU's per hour
An engineer is requested to replace a gauge on the high side of the system. The pressure graduation
rate should be:
At least 1.2 times the design pressure
An automatic expansion valve maintains a constant:
Evaporator pressure
During inspection of a facility, you notice that there has been failure to maintain water treatment of the
condenser water. The first evidence of a problem would be:
An increase in compressor head pressure
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,If the air lowers below the fans in an induced draft cooling tower become clogged, the result would be?
Higher return water temperature close and
You have a cold front and there is a sudden drop in temperature. The thermostat will cause the solenoid
valve to:
Close and pump the compressor down and shut down on low pressure
Cross connections and standpipe rises must be painted:
Red
Under certain circumstances, is it ok to chain an exit door?
No, it is never okay
How would you calibrate a thermometer?
Place the thermometer in a cup of ice water
What device automatically controls the speed of a steam turbine?
Governor valve
What happens when a steam turbine reaches critical speed?
Turbine will vibrate violently
Superheat increasing gradually over a week, what could be the cause?
Leak in system
What would happen if a TEV's spring were to break?
Flood the evaporator
Why are flare fittings not used in 3/4" diameter copper piping?
Soldered or brazed joints are better
In a refrigeration system with a high side float, frost on the suction line indicates?
There is an excess of refrigerant in the system
What color is the top of a TEV in an R22 system?
Green
Regardless of the safety classification, in the event of refrigerant leaks an RMO should be aware of?
Asphyxiation
What refrigerant is most often used in the bulb of a thermostatic expansion valve?
The same refrigerant that is in the system
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,When a thermostatic expansion valve is operating properly the end of the coil will contain?
Superheated vapor
If the external equalizing line is disconnected from a TEV?
The evaporator would flood
Which system is most likely to leak into the building spaces being cooled?
Direct systems
What device records the speed of the turbine's shaft?
Tachometer
What controls a solenoid valve on a motor?
Volts
How long does it take to warm up a steam turbine prior to start-up?
15 - 20 minutes
What device is used to control the speed of a steam turbine?
Governor valve
What is the heat transfer rate of a 30 ton system?
360,000 BTU's per hour
Refrigerant leaves the compressor as a?
Super-heated vapor
Water, oil and refrigerant would settle in a container in what order from top to bottom?
Oil, water, refrigerant.
The amount of refrigerant that passes through an orifice plates is determined by the?
Difference between high side and low side pressure
A centrifugal water pump is considered fully primed when?
It is full of liquid and air is vented
According to the NYC code, prior to recovering refrigerant from a unit, you must ensure that the
containers used for storage?
Are approved by the U. S department of transportation
What would be the best way to install a 90 degree turn in a hard copper piping system?
Use a factory made 90 degree elbow and braze
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, What is the maximum amount of refrigerant that could be stored in a machinery room?
300 pounds
An electrical wiring diagram shows?
Each of the wire connections (terminations) required by the system
What type of valve would be used to replace a pressure relief device, while keeping the system in
service?
Three way valve
A thermostatic expansion valve regulates ___?
Flow of refrigerant to the evaporator
Efficiency of the refrigerant cycle is affected by the operations of the condenser. Of the following, a
more efficient centrifugal compressor operation results from:
Lowering the condensing pressure
The heat removed from the refrigerant in a condenser is:
Sensible and latent heat
The refrigerant unit that you have been assigned to is being taken out of service for a major repair. You
have been assigned to withdraw refrigerant for storage in suitable containers. According to the NYC Fire
Code, you must ensure that the containers:
Are approved by the US Dept. of Transportation
Which of the following best describes how the cylinder unloader works?
Keep in the suction valve opened while the compressor is in the return stroke
In most semi-hermetic compressors, the suction vapor is used to:
Cool the motor
The amount of refrigerant that flows through the orifices of an economizer is determined by the:
Differences between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable:
To remove impurities from the system
The type of refrigerant system that is least likely to leak refrigerant into the building space that are being
cooled:
Indirect system
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