FDNY Z-51 Refrigeration Exam 2026/2027 | RSOE Fundamentals Study Guide, Practice Questions & Verified Answers

FDNY Z-51 Refrigeration Exam 2026/2027 |
RSOE Fundamentals Study Guide, Practice
Questions & Verified Answers
FDNY Z-51 REFRIGERATION EXAM 2026/2027 | RSOE FUNDAMENTALS STUDY
GUIDE

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• This comprehensive study guide contains verified exam questions covering all
FDNY Z-51 refrigeration fundamentals with detailed rationales for optimal
understanding and certification readiness.

• Study by working through each question systematically, reviewing rationales
thoroughly, and focusing on areas where you hesitate before attempting the actual
certification exam.

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QUESTION 1

What is the primary purpose of a compressor in a refrigeration system?

A) To condense the refrigerant vapor into liquid form

B) To circulate refrigerant and increase its pressure through mechanical action

C) To absorb heat from the space being cooled

D) To reduce the pressure of high-pressure refrigerant

E) To separate liquid and vapor refrigerant phases

✓ CORRECT ANSWER: B) To circulate refrigerant and increase its pressure
through mechanical action

RATIONALE: The compressor is the heart of any refrigeration cycle. Its primary
function is to take low-pressure refrigerant vapor from the evaporator and
compress it to high pressure, which raises its temperature above that of the
condenser cooling medium. This mechanical compression drives the refrigeration
cycle. While condensers condense vapor (A), evaporators absorb heat (C), and

,expansion devices reduce pressure (D), the compressor's defining role is increasing
pressure and circulation.

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QUESTION 2

Which of the following refrigerants is classified as a non-flammable, non-toxic
HFC refrigerant?

A) R-290 (Propane)

B) R-410A

C) R-600 (Butane)

D) R-32

E) R-717 (Ammonia)

✓ CORRECT ANSWER: B) R-410A

RATIONALE: R-410A is a hydrofluorocarbon (HFC) blend that is classified as non-
flammable and non-toxic, making it one of the most commonly used refrigerants in
HVAC/R applications. R-290 and R-600 are hydrocarbon refrigerants and are highly
flammable. R-32 is an HFC with lower global warming potential but has flammability
concerns. R-717 (ammonia) is toxic and corrosive, though non-flammable. R-410A
remains popular for its safety profile and performance characteristics.

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QUESTION 3

What is the relationship between pressure and saturation temperature in a
refrigerant?

A) They are independent of each other

B) Pressure and saturation temperature have a direct proportional relationship

C) Saturation temperature decreases as pressure increases

,D) Pressure has no effect on saturation temperature

E) Saturation temperature increases only with liquid refrigerant

✓ CORRECT ANSWER: B) Pressure and saturation temperature have a direct
proportional relationship

RATIONALE: This is a fundamental principle in refrigeration thermodynamics. For
any given refrigerant, as pressure increases, the saturation temperature increases
proportionally. This relationship is shown on a pressure-enthalpy diagram and is
critical for understanding how refrigeration cycles operate. For example, if you
increase the pressure on R-410A, its saturation temperature will rise. This direct
relationship is why technicians use pressure gauges to determine refrigerant
temperatures without a separate thermometer.

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QUESTION 4

Which component of a refrigeration system removes heat from the space
being cooled?

A) The condenser

B) The compressor

C) The evaporator

D) The expansion device

E) The receiver

✓ CORRECT ANSWER: C) The evaporator

RATIONALE: The evaporator is the component where the refrigerant evaporates
(changes from liquid to vapor) at low pressure and temperature, absorbing heat
from the indoor space or product being cooled. This heat absorption causes the
refrigerant to evaporate, removing thermal energy from the environment. The
condenser releases heat (A), the compressor increases pressure (B), the expansion

, device reduces pressure (D), and the receiver stores liquid refrigerant (E). Only the
evaporator has the primary function of cooling.

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QUESTION 5

What does GWP stand for in refrigerant classification?

A) Global Weight Percentage

B) Gross Warming Potential

C) Global Warming Potential

D) Gas Weighing Parameter

E) General Water Pressure

✓ CORRECT ANSWER: C) Global Warming Potential

RATIONALE: Global Warming Potential (GWP) is a measure of how much a given
mass of a refrigerant contributes to global warming compared to carbon dioxide
(CO2) over a specified period, typically 100 years. CO2 is assigned a GWP of 1, and
other refrigerants are rated relative to this baseline. Refrigerants with lower GWP
values are considered more environmentally friendly. The EPA and ASHRAE use
GWP to regulate refrigerant production and phase-out schedules under regulations
like the Kigali Amendment.

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QUESTION 6

What is the main function of a condenser in a refrigeration system?

A) To increase the temperature of liquid refrigerant

B) To reject heat by condensing high-pressure refrigerant vapor into liquid

C) To absorb heat from the evaporator

D) To reduce refrigerant pressure