FDNY Z-51 REFRIGERATION LICENSE EXAM 200
QUESTIONS WITH VERIFIED ANSWERS & DETAILED
RATIONALES
Table of Contents
Section Domain Approx. Page
Questions Reference
1 Refrigeration Cycle Theory & 1–30 1
Thermodynamics
2 Compressors 31–60 4
3 Condensers, Evaporators & Heat 61–90 8
Exchangers
4 Metering Devices & Accessories 91–115 12
5 Refrigerants & Environmental Safety 116–140 15
6 Pumps, Cooling Towers & Steam 141–160 18
Turbines
7 Electrical Components & Controls 161–180 20
8 Fire Safety, NYC Codes & Plant 181–200 23
Operations
,SECTION 1: REFRIGERATION CYCLE THEORY & THERMODYNAMICS
Question 1
What are the four main components of the vapor-compression
refrigeration cycle?
A. Compressor, Condenser, Receiver, Evaporator
B. Compressor, Condenser, Expansion Valve, Evaporator
C. Compressor, Condenser, Expansion Valve, Accumulator
D. Compressor, Condenser, Filter-Drier, Evaporator
Correct Answer: B
Rationale: The four main components of the vapor-compression
refrigeration cycle are the compressor, condenser, expansion valve (or
metering device), and evaporator. These components work together to
circulate refrigerant, remove heat from the conditioned space, and
reject it to the environment. The receiver, accumulator, and filter-drier
are auxiliary components that support the main cycle but are not
considered the four primary components.
Question 2
What is the primary function of the compressor in a refrigeration
system?
A. To absorb heat from the refrigerated space
B. To remove heat from the refrigerant
C. To increase the pressure and temperature of the refrigerant vapor
D. To reduce the pressure of the refrigerant liquid
Correct Answer: C
Rationale: The compressor's primary function is to draw low-pressure,
low-temperature refrigerant vapor from the evaporator and compress
it, significantly increasing both its pressure and temperature. This high-
pressure, high-temperature vapor is then discharged to the condenser
,where heat is rejected. Without the compressor, the refrigerant would
not circulate through the system.
Question 3
What is the primary function of the condenser in a refrigeration
system?
A. To absorb heat from the refrigerated space
B. To remove heat from the high-pressure refrigerant vapor
C. To increase the pressure of the refrigerant
D. To reduce the pressure of the refrigerant liquid
Correct Answer: B
Rationale: The condenser removes heat from the high-pressure, high-
temperature refrigerant vapor discharged by the compressor. As heat is
removed, the refrigerant condenses from a vapor to a liquid state. The
heat is rejected to the surrounding air (air-cooled condenser) or water
(water-cooled condenser). This is the stage where the refrigerant rejects
the heat absorbed in the evaporator plus the heat of compression.
Question 4
What is the primary function of the expansion valve (metering device)?
A. To increase refrigerant pressure
B. To increase refrigerant temperature
C. To reduce refrigerant pressure and temperature
D. To compress refrigerant vapor
Correct Answer: C
Rationale: The expansion valve (metering device) reduces the pressure
and temperature of the liquid refrigerant as it passes from the high-
pressure side of the system to the low-pressure side. This pressure drop
causes a portion of the liquid refrigerant to flash into vapor, cooling the
remaining liquid. The cooled, low-pressure liquid-vapor mixture then
, enters the evaporator where it can absorb heat from the refrigerated
space.
Question 5
What is the primary function of the evaporator in a refrigeration
system?
A. To compress refrigerant vapor
B. To remove heat from the refrigerant
C. To absorb heat from the refrigerated space
D. To reduce refrigerant pressure
Correct Answer: C
Rationale: The evaporator absorbs heat from the refrigerated space by
allowing the low-pressure, low-temperature liquid refrigerant to boil
and vaporize. As the refrigerant absorbs heat, it changes from a liquid to
a vapor. This is the stage where the refrigerant absorbs heat from the
space being cooled.
Question 6
One ton of refrigeration is defined as the removal of how many BTUs
per hour?
A. 10,000 BTU/hr
B. 12,000 BTU/hr
C. 15,000 BTU/hr
D. 18,000 BTU/hr
Correct Answer: B
Rationale: One ton of refrigeration equals 12,000 BTU/hr, based on the
latent heat needed to melt one ton of ice in 24 hours.
Question 7
Superheat is defined as:
QUESTIONS WITH VERIFIED ANSWERS & DETAILED
RATIONALES
Table of Contents
Section Domain Approx. Page
Questions Reference
1 Refrigeration Cycle Theory & 1–30 1
Thermodynamics
2 Compressors 31–60 4
3 Condensers, Evaporators & Heat 61–90 8
Exchangers
4 Metering Devices & Accessories 91–115 12
5 Refrigerants & Environmental Safety 116–140 15
6 Pumps, Cooling Towers & Steam 141–160 18
Turbines
7 Electrical Components & Controls 161–180 20
8 Fire Safety, NYC Codes & Plant 181–200 23
Operations
,SECTION 1: REFRIGERATION CYCLE THEORY & THERMODYNAMICS
Question 1
What are the four main components of the vapor-compression
refrigeration cycle?
A. Compressor, Condenser, Receiver, Evaporator
B. Compressor, Condenser, Expansion Valve, Evaporator
C. Compressor, Condenser, Expansion Valve, Accumulator
D. Compressor, Condenser, Filter-Drier, Evaporator
Correct Answer: B
Rationale: The four main components of the vapor-compression
refrigeration cycle are the compressor, condenser, expansion valve (or
metering device), and evaporator. These components work together to
circulate refrigerant, remove heat from the conditioned space, and
reject it to the environment. The receiver, accumulator, and filter-drier
are auxiliary components that support the main cycle but are not
considered the four primary components.
Question 2
What is the primary function of the compressor in a refrigeration
system?
A. To absorb heat from the refrigerated space
B. To remove heat from the refrigerant
C. To increase the pressure and temperature of the refrigerant vapor
D. To reduce the pressure of the refrigerant liquid
Correct Answer: C
Rationale: The compressor's primary function is to draw low-pressure,
low-temperature refrigerant vapor from the evaporator and compress
it, significantly increasing both its pressure and temperature. This high-
pressure, high-temperature vapor is then discharged to the condenser
,where heat is rejected. Without the compressor, the refrigerant would
not circulate through the system.
Question 3
What is the primary function of the condenser in a refrigeration
system?
A. To absorb heat from the refrigerated space
B. To remove heat from the high-pressure refrigerant vapor
C. To increase the pressure of the refrigerant
D. To reduce the pressure of the refrigerant liquid
Correct Answer: B
Rationale: The condenser removes heat from the high-pressure, high-
temperature refrigerant vapor discharged by the compressor. As heat is
removed, the refrigerant condenses from a vapor to a liquid state. The
heat is rejected to the surrounding air (air-cooled condenser) or water
(water-cooled condenser). This is the stage where the refrigerant rejects
the heat absorbed in the evaporator plus the heat of compression.
Question 4
What is the primary function of the expansion valve (metering device)?
A. To increase refrigerant pressure
B. To increase refrigerant temperature
C. To reduce refrigerant pressure and temperature
D. To compress refrigerant vapor
Correct Answer: C
Rationale: The expansion valve (metering device) reduces the pressure
and temperature of the liquid refrigerant as it passes from the high-
pressure side of the system to the low-pressure side. This pressure drop
causes a portion of the liquid refrigerant to flash into vapor, cooling the
remaining liquid. The cooled, low-pressure liquid-vapor mixture then
, enters the evaporator where it can absorb heat from the refrigerated
space.
Question 5
What is the primary function of the evaporator in a refrigeration
system?
A. To compress refrigerant vapor
B. To remove heat from the refrigerant
C. To absorb heat from the refrigerated space
D. To reduce refrigerant pressure
Correct Answer: C
Rationale: The evaporator absorbs heat from the refrigerated space by
allowing the low-pressure, low-temperature liquid refrigerant to boil
and vaporize. As the refrigerant absorbs heat, it changes from a liquid to
a vapor. This is the stage where the refrigerant absorbs heat from the
space being cooled.
Question 6
One ton of refrigeration is defined as the removal of how many BTUs
per hour?
A. 10,000 BTU/hr
B. 12,000 BTU/hr
C. 15,000 BTU/hr
D. 18,000 BTU/hr
Correct Answer: B
Rationale: One ton of refrigeration equals 12,000 BTU/hr, based on the
latent heat needed to melt one ton of ice in 24 hours.
Question 7
Superheat is defined as:
