FDNY Z51 RMO CERTIFICATION PAPER
2026 FULL SOLUTIONS VERIFIED GRADED
A+
⩥ The heat removed from the refrigerant in a condenser is: Answer:
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: Answer: Are approved by the
US Dept. of Transportation
⩥ Which of the following best describes how the cylinder unloader
works? Answer: 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:
Answer: Cool the motor
⩥ The amount of refrigerant that flows through the orifices of an
economizer is determined by the: Answer: Differences between the high
side and low side pressure
,⩥ The installation of an inline refrigerant cleaning system is advisable:
Answer: 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: Answer: Indirect system
⩥ The suction pressure of a reciprocating compressor is 65 PSIG. The
discharge pressure of this compressor is 120 PSIG. The atmospheric is
14.7 PSI. The compression ratio for the given condition is closest to:
Answer: 1.69
⩥ A superheated vapor is: Answer: Dry vapor above the saturation
temperature
⩥ A refrigerant engineer verifies that a condenser water pump is
cavitating. Of the following, the most likely cause for this condition is:
Answer: A faulty cooling tower water level controller
⩥ A centrifugal water pump is known as a lift pump when the: Answer:
The water supply to the pump suction inlet is below the pump level
⩥ A TXV is used to maintain constant: Answer: Evaporator superheat
,⩥ The chilled water supply to the building is 55 deg F. If the chiller is
being used for human comfort, should you be concerned about this, and
why? Answer: Yes, this temp is too high for human comfort purposes
⩥ The packing gland of a centrifugal pump serves to: Answer: The drip
part of the packing gland gives evidence that there is water in the pump
⩥ Capacity control of reciprocating hermetic compressor is typically
achieved through: Answer: Operation of the hot gas bypass valve
⩥ The most important reason to sub-cool the refrigerant in the condenser
is to ensure that: Answer: A pure liquid refrigerant will enter the
metering device
⩥ A refrigeration engineer is logging readings from a reciprocating
system. Compressor discharge temperature have dropped significantly
and the suction line pressure is high. Which of the following that may be
causing this set of condition? Answer: An expansion valve that is open
too wide
⩥ A low side float valve is used to maintain: Answer: The level of the
refrigerant in the evaporator
⩥ Regarding fire safety, which ASHRAE refrigerant safety classification
indicates no flammability and lower toxicity? Answer: A1
, ⩥ When an expansion valve is operating properly, at the end of the
evaporator will contain: Answer: Only superheated vapor
⩥ What information is not contained in a Material Safety Data Sheet?
Answer: Cost of the material
⩥ In a steam turbine, what is the function of the Kingsbury thrust
bearing? Answer: Maintain axial positioning of the rotor shaft
⩥ A centrifugal water pump is considered to the fully primed when?
Answer: The pump is full of liquid
⩥ Copper tubing refrigerant lines must be installed for a new system. It
is a well known service practice that tubing collapses at bends that must
be made, the refrigerant engineer should use? Answer: Level type tubing
bender
⩥ A reciprocating compressor is making a knocking sound during
operation. If the refrigerant worn parts are not causing the knocking,
what probably the cause? Answer: Slugging of the liquid refrigerant
⩥ In order for a refrigerant to become superheated, it must be heated in a
section of the low side refrigerant line: Answer: Where no liquid
refrigerant is present
2026 FULL SOLUTIONS VERIFIED GRADED
A+
⩥ The heat removed from the refrigerant in a condenser is: Answer:
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: Answer: Are approved by the
US Dept. of Transportation
⩥ Which of the following best describes how the cylinder unloader
works? Answer: 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:
Answer: Cool the motor
⩥ The amount of refrigerant that flows through the orifices of an
economizer is determined by the: Answer: Differences between the high
side and low side pressure
,⩥ The installation of an inline refrigerant cleaning system is advisable:
Answer: 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: Answer: Indirect system
⩥ The suction pressure of a reciprocating compressor is 65 PSIG. The
discharge pressure of this compressor is 120 PSIG. The atmospheric is
14.7 PSI. The compression ratio for the given condition is closest to:
Answer: 1.69
⩥ A superheated vapor is: Answer: Dry vapor above the saturation
temperature
⩥ A refrigerant engineer verifies that a condenser water pump is
cavitating. Of the following, the most likely cause for this condition is:
Answer: A faulty cooling tower water level controller
⩥ A centrifugal water pump is known as a lift pump when the: Answer:
The water supply to the pump suction inlet is below the pump level
⩥ A TXV is used to maintain constant: Answer: Evaporator superheat
,⩥ The chilled water supply to the building is 55 deg F. If the chiller is
being used for human comfort, should you be concerned about this, and
why? Answer: Yes, this temp is too high for human comfort purposes
⩥ The packing gland of a centrifugal pump serves to: Answer: The drip
part of the packing gland gives evidence that there is water in the pump
⩥ Capacity control of reciprocating hermetic compressor is typically
achieved through: Answer: Operation of the hot gas bypass valve
⩥ The most important reason to sub-cool the refrigerant in the condenser
is to ensure that: Answer: A pure liquid refrigerant will enter the
metering device
⩥ A refrigeration engineer is logging readings from a reciprocating
system. Compressor discharge temperature have dropped significantly
and the suction line pressure is high. Which of the following that may be
causing this set of condition? Answer: An expansion valve that is open
too wide
⩥ A low side float valve is used to maintain: Answer: The level of the
refrigerant in the evaporator
⩥ Regarding fire safety, which ASHRAE refrigerant safety classification
indicates no flammability and lower toxicity? Answer: A1
, ⩥ When an expansion valve is operating properly, at the end of the
evaporator will contain: Answer: Only superheated vapor
⩥ What information is not contained in a Material Safety Data Sheet?
Answer: Cost of the material
⩥ In a steam turbine, what is the function of the Kingsbury thrust
bearing? Answer: Maintain axial positioning of the rotor shaft
⩥ A centrifugal water pump is considered to the fully primed when?
Answer: The pump is full of liquid
⩥ Copper tubing refrigerant lines must be installed for a new system. It
is a well known service practice that tubing collapses at bends that must
be made, the refrigerant engineer should use? Answer: Level type tubing
bender
⩥ A reciprocating compressor is making a knocking sound during
operation. If the refrigerant worn parts are not causing the knocking,
what probably the cause? Answer: Slugging of the liquid refrigerant
⩥ In order for a refrigerant to become superheated, it must be heated in a
section of the low side refrigerant line: Answer: Where no liquid
refrigerant is present
