FDNY Z-51 REFRIGERATION EXAM: COMPLETE TEST
BANK WITH 150 NGN-STYLE QUESTIONS, VERIFIED
ANSWERS & DETAILED RATIONALES | NYC FIRE CODE
2026/2027 EDITION
,Core Domains
• Refrigeration Cycle Theory and Thermodynamics
• Compressor Operation, Types, and Capacity Control
• Condensers, Evaporators, and Metering Devices
• Refrigerant Properties, Classifications, and Safety
• System Controls, Safety Devices, and Electrical Theory
• Centrifugal Pumps, Cooling Towers, and Steam Turbines
• NYC Fire Code, ASHRAE Standards, and Permit Requirements
• Plant Operations, Maintenance, and Recordkeeping
• Machine Room Safety and Emergency Procedures
• A2L Refrigerant Compliance and EPA Regulations
Introduction
The FDNY Z-51 Refrigerating System Operating Engineer
examination assesses the knowledge, skills, and decision-making
abilities required to safely operate, maintain, and supervise
refrigeration systems in New York City. The exam evaluates
foundational refrigeration theory, applied professional knowledge,
regulatory and legal compliance, ethical standards, and real-world
scenario-based problem solving. Questions emphasize practical
application, code interpretation, and emergency response.
Candidates are expected to demonstrate competency across
multiple-choice and scenario-based formats that reflect the
responsibilities of a certified operating engineer under the New York
,City Fire Code and related standards. A passing score of 70% is
required to earn the Certificate of Qualification.
SECTION ONE: QUESTIONS 1–100
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
B. Compressor, Condenser, Expansion Valve, Evaporator
RATIONALE: The four main components of the vapor-
compression refrigeration cycle are the compressor, condenser,
expansion valve, and evaporator. These components work together
to circulate refrigerant, remove heat from the conditioned space,
and reject it to the environment. Receivers, accumulators, and filter-
driers are auxiliary 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
C. To increase the pressure and temperature of the refrigerant
vapor
RATIONALE: The compressor draws low-pressure, low-
temperature refrigerant vapor from the evaporator and compresses
it, increasing both pressure and temperature. This high-pressure
vapor then flows to the condenser where heat is rejected.
Question 3
A refrigeration system removes 120,000 Btu/h from a conditioned
space while consuming 12 kW of electrical power. Using 1 kW ≈
3,412 Btu/h, what is the coefficient of performance (COP)?
A. 1.93
B. 2.93
C. 3.93
D. 4.93
B. 2.93
RATIONALE: COP = Refrigeration effect / Work input. Work
input = 12 kW × 3,412 Btu/h per kW = 40,944 Btu/h. COP = 120,000
/ 40,944 ≈ 2.93.
Question 4
Under the updated exam structure effective July 1, 2026, the RSOE
written exam is officially titled:
BANK WITH 150 NGN-STYLE QUESTIONS, VERIFIED
ANSWERS & DETAILED RATIONALES | NYC FIRE CODE
2026/2027 EDITION
,Core Domains
• Refrigeration Cycle Theory and Thermodynamics
• Compressor Operation, Types, and Capacity Control
• Condensers, Evaporators, and Metering Devices
• Refrigerant Properties, Classifications, and Safety
• System Controls, Safety Devices, and Electrical Theory
• Centrifugal Pumps, Cooling Towers, and Steam Turbines
• NYC Fire Code, ASHRAE Standards, and Permit Requirements
• Plant Operations, Maintenance, and Recordkeeping
• Machine Room Safety and Emergency Procedures
• A2L Refrigerant Compliance and EPA Regulations
Introduction
The FDNY Z-51 Refrigerating System Operating Engineer
examination assesses the knowledge, skills, and decision-making
abilities required to safely operate, maintain, and supervise
refrigeration systems in New York City. The exam evaluates
foundational refrigeration theory, applied professional knowledge,
regulatory and legal compliance, ethical standards, and real-world
scenario-based problem solving. Questions emphasize practical
application, code interpretation, and emergency response.
Candidates are expected to demonstrate competency across
multiple-choice and scenario-based formats that reflect the
responsibilities of a certified operating engineer under the New York
,City Fire Code and related standards. A passing score of 70% is
required to earn the Certificate of Qualification.
SECTION ONE: QUESTIONS 1–100
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
B. Compressor, Condenser, Expansion Valve, Evaporator
RATIONALE: The four main components of the vapor-
compression refrigeration cycle are the compressor, condenser,
expansion valve, and evaporator. These components work together
to circulate refrigerant, remove heat from the conditioned space,
and reject it to the environment. Receivers, accumulators, and filter-
driers are auxiliary 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
C. To increase the pressure and temperature of the refrigerant
vapor
RATIONALE: The compressor draws low-pressure, low-
temperature refrigerant vapor from the evaporator and compresses
it, increasing both pressure and temperature. This high-pressure
vapor then flows to the condenser where heat is rejected.
Question 3
A refrigeration system removes 120,000 Btu/h from a conditioned
space while consuming 12 kW of electrical power. Using 1 kW ≈
3,412 Btu/h, what is the coefficient of performance (COP)?
A. 1.93
B. 2.93
C. 3.93
D. 4.93
B. 2.93
RATIONALE: COP = Refrigeration effect / Work input. Work
input = 12 kW × 3,412 Btu/h per kW = 40,944 Btu/h. COP = 120,000
/ 40,944 ≈ 2.93.
Question 4
Under the updated exam structure effective July 1, 2026, the RSOE
written exam is officially titled:
