FDNY Z51 Responsible Managing Officer Final Paper
— Complete Questions with Bold-Italic Verified
Answers and Italic Rationales Latest Update This
Year.Pdf
COVERING Refrigeration Cycle Fundamentals, Compressor Capacity Control, Pump Cavitation
and Seals, Cooling Tower Water Treatment, Refrigerant Leak Detection and Safety, Machine Room
Storage Limits, Fire Protection Systems, Emergency Response, and FDNY Code Compliance for
RMO Certification
SECTION 1: REFRIGERATION FUNDAMENTALS & THERMODYNAMICS (Questions 1–
40)
1. One ton of refrigeration is defined as the removal of how many BTUs per hour from
a space?
A) 10,000 BTU/hr
B) 12,000 BTU/hr
C) 15,000 BTU/hr
D) 18,000 BTU/hr
One ton of refrigeration equals 12,000 BTU/hr, based on the latent heat needed to melt one
ton of ice in 24 hours.
,2. How many BTUs are required to melt one pound of ice at 32°F to water at 32°F?
A) 144 BTU
B) 1 BTU
C) 970 BTU
D) 180 BTU
The latent heat of fusion for water/ice is 144 BTU per pound.
3. What is the latent heat of vaporization of water at atmospheric pressure?
A) 144 BTU per pound
B) 33 BTU per pound
C) 970 BTU per pound
D) 1 BTU per pound
Water absorbs approximately 970 BTU per pound when changing from liquid to vapor at
212°F and atmospheric pressure.
4. A refrigeration system absorbs 120,000 Btu/h and receives 20,000 Btu/h of
compressor input. Approximately how much heat must be rejected at the condenser?
A) 100,000 Btu/h
B) 140,000 Btu/h
C) 120,000 Btu/h
D) 20,000 Btu/h
The condenser must reject the heat absorbed in the evaporator plus the heat of
compression (120,000 + 20,000 = 140,000 Btu/h).
5. What is the primary purpose of a pressure-temperature (P-T) chart when servicing
a refrigerating system?
A) To determine the saturation temperature at a given pressure
B) To calculate electrical motor horsepower
C) To measure refrigerant flow rate
,D) To determine compressor oil viscosity
A P-T chart relates refrigerant pressure to its saturation temperature, allowing the engineer
to verify system operation and superheat/subcooling.
6. A superheated vapor is best described as which of the following?
A) Dry vapor at the saturation temperature
B) Dry saturated vapor
C) Dry vapor above the saturation temperature
D) Vapor with a minimal amount of included liquid
Superheated vapor is dry vapor that has been heated above its saturation temperature at a
given pressure.
7. The total amount of heat to be removed from the refrigerant in a condenser equals
the heat picked up in which components?
A) Evaporator only
B) Compressor only
C) Evaporator plus the heat of compression
D) Evaporator minus the heat of compression
The condenser rejects the heat absorbed in the evaporator plus the heat added by the
compressor.
8. Subcooling the refrigerant in the condenser is most important for which reason?
A) To ensure that pure liquid refrigerant enters the metering device
B) To increase compressor discharge temperature
C) To reduce evaporator pressure
D) To increase flash gas in the evaporator
Subcooling ensures a solid column of liquid reaches the metering device, preventing flash
gas from reducing system capacity.
, 9. What is the compression ratio when the suction pressure is 65 PSIG, the discharge
pressure is 120 PSIG, and atmospheric pressure is 14.7 PSI?
A) 2.07
B) 4.41
C) *1.69*
D) 1.84
Compression ratio = (discharge absolute pressure) ÷ (suction absolute pressure) =
(120+14.7)/(65+14.7) = 134.7/79.7 ≈ 1.69.
10. The efficiency of the refrigerant cycle is most directly affected by the operation of
which component?
A) The evaporator
B) The condenser
C) The compressor
D) The expansion valve
The condenser’s ability to reject heat determines head pressure and directly impacts overall
cycle efficiency.
11. A more efficient centrifugal compressor operation results from which of the
following conditions?
A) Raising the condenser liquid level to the maximum
B) Lowering the chilled water set point
C) Raising the condenser head pressure
D) Lowering the condensing pressure
Lowering condensing pressure reduces the compression ratio the centrifugal compressor
must overcome, improving efficiency.
12. The heat removed from the refrigerant in a condenser consists of which types of
heat?
— Complete Questions with Bold-Italic Verified
Answers and Italic Rationales Latest Update This
Year.Pdf
COVERING Refrigeration Cycle Fundamentals, Compressor Capacity Control, Pump Cavitation
and Seals, Cooling Tower Water Treatment, Refrigerant Leak Detection and Safety, Machine Room
Storage Limits, Fire Protection Systems, Emergency Response, and FDNY Code Compliance for
RMO Certification
SECTION 1: REFRIGERATION FUNDAMENTALS & THERMODYNAMICS (Questions 1–
40)
1. One ton of refrigeration is defined as the removal of how many BTUs per hour from
a space?
A) 10,000 BTU/hr
B) 12,000 BTU/hr
C) 15,000 BTU/hr
D) 18,000 BTU/hr
One ton of refrigeration equals 12,000 BTU/hr, based on the latent heat needed to melt one
ton of ice in 24 hours.
,2. How many BTUs are required to melt one pound of ice at 32°F to water at 32°F?
A) 144 BTU
B) 1 BTU
C) 970 BTU
D) 180 BTU
The latent heat of fusion for water/ice is 144 BTU per pound.
3. What is the latent heat of vaporization of water at atmospheric pressure?
A) 144 BTU per pound
B) 33 BTU per pound
C) 970 BTU per pound
D) 1 BTU per pound
Water absorbs approximately 970 BTU per pound when changing from liquid to vapor at
212°F and atmospheric pressure.
4. A refrigeration system absorbs 120,000 Btu/h and receives 20,000 Btu/h of
compressor input. Approximately how much heat must be rejected at the condenser?
A) 100,000 Btu/h
B) 140,000 Btu/h
C) 120,000 Btu/h
D) 20,000 Btu/h
The condenser must reject the heat absorbed in the evaporator plus the heat of
compression (120,000 + 20,000 = 140,000 Btu/h).
5. What is the primary purpose of a pressure-temperature (P-T) chart when servicing
a refrigerating system?
A) To determine the saturation temperature at a given pressure
B) To calculate electrical motor horsepower
C) To measure refrigerant flow rate
,D) To determine compressor oil viscosity
A P-T chart relates refrigerant pressure to its saturation temperature, allowing the engineer
to verify system operation and superheat/subcooling.
6. A superheated vapor is best described as which of the following?
A) Dry vapor at the saturation temperature
B) Dry saturated vapor
C) Dry vapor above the saturation temperature
D) Vapor with a minimal amount of included liquid
Superheated vapor is dry vapor that has been heated above its saturation temperature at a
given pressure.
7. The total amount of heat to be removed from the refrigerant in a condenser equals
the heat picked up in which components?
A) Evaporator only
B) Compressor only
C) Evaporator plus the heat of compression
D) Evaporator minus the heat of compression
The condenser rejects the heat absorbed in the evaporator plus the heat added by the
compressor.
8. Subcooling the refrigerant in the condenser is most important for which reason?
A) To ensure that pure liquid refrigerant enters the metering device
B) To increase compressor discharge temperature
C) To reduce evaporator pressure
D) To increase flash gas in the evaporator
Subcooling ensures a solid column of liquid reaches the metering device, preventing flash
gas from reducing system capacity.
, 9. What is the compression ratio when the suction pressure is 65 PSIG, the discharge
pressure is 120 PSIG, and atmospheric pressure is 14.7 PSI?
A) 2.07
B) 4.41
C) *1.69*
D) 1.84
Compression ratio = (discharge absolute pressure) ÷ (suction absolute pressure) =
(120+14.7)/(65+14.7) = 134.7/79.7 ≈ 1.69.
10. The efficiency of the refrigerant cycle is most directly affected by the operation of
which component?
A) The evaporator
B) The condenser
C) The compressor
D) The expansion valve
The condenser’s ability to reject heat determines head pressure and directly impacts overall
cycle efficiency.
11. A more efficient centrifugal compressor operation results from which of the
following conditions?
A) Raising the condenser liquid level to the maximum
B) Lowering the chilled water set point
C) Raising the condenser head pressure
D) Lowering the condensing pressure
Lowering condensing pressure reduces the compression ratio the centrifugal compressor
must overcome, improving efficiency.
12. The heat removed from the refrigerant in a condenser consists of which types of
heat?
