100+ Free RETA CARO Practice Questions

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In a basic vapor-compression refrigeration cycle, which component is responsible for absorbing heat from the refrigerated space?

Compressor

Condenser

Evaporator

Receiver

to track

2026 Statistics

Key Facts: RETA CARO Exam

110

Exam Questions

RETA CARO handbook

3 hours

Time Limit

RETA CARO handbook

Minimum Passing Score

RETA CARO handbook

$560

Non-Member Exam Fee

RETA application

$390

RETA Member Exam Fee

RETA application

No experience

Experience Required

RETA CARO (entry-level)

3 years

Recertification Cycle

RETA recertification

400+

Kryterion Test Centers

RETA scheduling

The RETA CARO exam has 110 multiple-choice items, a 3-hour time limit, and a 70 minimum passing score. There are no experience prerequisites, so CARO is commonly the first RETA credential for operators, technicians, and apprentices working with anhydrous ammonia (R-717) systems. Content covers refrigeration fundamentals, the refrigeration cycle, refrigerant properties, saturated refrigerant tables, compressor types, compressor operation and maintenance, lubrication, evaporators and cooling units, condensers and high-pressure receivers, purging, and safety/hazards/prevention including IIAR, OSHA PSM (29 CFR 1910.119), EPA RMP (40 CFR Part 68), IDLH/PEL exposure limits, and ammonia SDS firefighting information.

Sample RETA CARO Practice Questions

Try these sample questions to test your RETA CARO exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a basic vapor-compression refrigeration cycle, which component is responsible for absorbing heat from the refrigerated space?

A.Compressor

B.Condenser

C.Evaporator

D.Receiver

Explanation: The evaporator is the heat-absorbing heat exchanger. Low-pressure liquid refrigerant boils inside the evaporator, pulling latent heat from the air or product and turning into low-pressure vapor that returns to the compressor.

2Anhydrous ammonia used as a refrigerant in industrial systems is commonly designated as which ASHRAE refrigerant number?

A.R-22

B.R-134a

C.R-717

D.R-404A

Explanation: Ammonia (NH3) carries the ASHRAE designation R-717. The 700-series is reserved for inorganic refrigerants, and 17 is the molecular weight of ammonia. CARO candidates must recognize this designation on labels and safety documents.

3What is the primary federal regulation in the United States that requires a Process Safety Management (PSM) program for industrial ammonia refrigeration systems containing 10,000 lb or more of ammonia?

A.OSHA 29 CFR 1910.119

B.OSHA 29 CFR 1910.147

C.EPA 40 CFR 82

D.DOT 49 CFR 173

Explanation: OSHA's Process Safety Management standard, 29 CFR 1910.119, covers processes with highly hazardous chemicals including ammonia above the 10,000 lb threshold. It requires process hazard analysis, operating procedures, mechanical integrity, and management of change.

4During normal operation, what is the correct flow of refrigerant through the four main components of a single-stage vapor-compression cycle starting at the compressor discharge?

A.Compressor -> evaporator -> expansion device -> condenser

B.Compressor -> condenser -> expansion device -> evaporator

C.Compressor -> expansion device -> condenser -> evaporator

D.Compressor -> condenser -> evaporator -> expansion device

Explanation: High-pressure vapor leaves the compressor, rejects heat and condenses in the condenser, then the liquid is metered through the expansion device and boils in the evaporator before returning to the compressor.

5Which device is typically used to meter liquid refrigerant into the evaporator while dropping pressure from the high side to the low side of the system?

A.Check valve

B.Thermostatic expansion valve (TXV)

C.Oil separator

D.Suction accumulator

Explanation: A TXV modulates liquid flow based on evaporator superheat, dropping pressure to the evaporator saturation pressure while maintaining stable superheat. Other common metering devices include hand expansion valves and electronic expansion valves.

6The term 'ton of refrigeration' represents approximately how much cooling capacity?

A.2,000 Btu/h

B.12,000 Btu/h

C.24,000 Btu/h

D.120,000 Btu/h

Explanation: One ton of refrigeration equals 12,000 Btu/h, the rate needed to melt 2,000 lb of ice in 24 hours. CARO candidates must convert between tons and Btu/h when reading compressor and evaporator capacity data.

7What does 'saturation' mean in refrigeration tables and system operation?

A.The refrigerant has absorbed all the oil it can hold

B.The refrigerant is at the pressure and temperature at which liquid and vapor coexist

C.The refrigerant has reached its maximum superheat

D.The refrigerant has become non-condensable

Explanation: Saturation is the equilibrium state where liquid and vapor coexist. On a saturated ammonia table, each saturation pressure corresponds to one saturation temperature. Operators read this relationship to confirm evaporator and condenser conditions.

8Per the ammonia Safety Data Sheet, which extinguishing medium is generally preferred when responding to a small ammonia fire?

A.CO2 extinguisher

B.Halon 1301

C.Water spray or water fog

D.Sand

Explanation: Water fog or water spray is preferred because it absorbs ammonia vapor and keeps containers cool. The ammonia SDS warns against using CO2 because it can displace oxygen in confined spaces and does not absorb ammonia.

9What is the atmospheric-pressure boiling point of anhydrous ammonia?

A.32 degrees F

B.-28 degrees F

C.-40 degrees F

D.-108 degrees F

Explanation: Ammonia boils at approximately -28 degrees F at atmospheric pressure. This low boiling point makes it useful for industrial refrigeration but also means a liquid ammonia release flash-boils to vapor that is colder than ambient air.

10Which common compressor type in industrial ammonia systems uses two meshing helical rotors to compress vapor?

A.Reciprocating compressor

B.Screw compressor

C.Centrifugal compressor

D.Scroll compressor

Explanation: A twin-screw compressor uses two helical rotors (male and female) in mesh; gas trapped between the rotors is reduced in volume as it travels the length of the rotor pair. Screw compressors dominate the 150-700 hp industrial ammonia range.

About the RETA CARO Exam

RETA CARO is the entry-level Certified Assistant Refrigeration Operator credential. CARO verifies that an operator has the basic knowledge to safely assist with industrial ammonia refrigeration system operations under the supervision of a more experienced operator.

Assessment

Single exam, 110 multiple-choice questions

Time Limit

3 hours

Passing Score

70 (minimum passing score)

Exam Fee

$560 non-member / $390 RETA member (Refrigerating Engineers and Technicians Association (RETA))

RETA CARO Exam Content Outline

11%

Refrigeration Fundamentals

Btu, ton of refrigeration, sensible/latent heat, specific heat, superheat, subcooling, and typical industrial temperature ranges for coolers, freezers, and blast freezers.

Refrigeration Cycle

Vapor-compression cycle flow, expansion devices, heat rejection balance, cascade systems, intercoolers, and the role of each component (compressor, condenser, evaporator, expansion device, receiver).

Properties of Refrigerants

Ammonia as R-717, boiling point, flammability range, density vs. air, odor threshold, and why ammonia is used in industrial refrigeration despite its toxicity.

Saturated Refrigerant Tables

Reading saturation pressure/temperature relationships for ammonia, including vacuum conditions below 0 psig and common operating points.

Types of Compressors

Reciprocating, screw, centrifugal, and scroll compressors and the role each plays in industrial ammonia service, including screw Vi and slide valve capacity control.

14%

Operation and Maintenance of Compressors

Suction/discharge valves, compression ratio, volumetric efficiency, startup sequence, unloaders, liquid slugging, discharge temperature, and troubleshooting.

16%

Lubrication

Oil function, miscibility with ammonia, oil separators, oil charging, synthetic and mineral oils, net oil pressure, low-side oil logging, and safe oil draining procedures.

10%

Evaporators and Cooling Units

DX vs flooded operation, frost and defrost (including hot gas defrost), fan rotation, TXV behavior, external equalizers, accumulators, and level control in surge drums.

12%

Condensers and High-Pressure Receivers

Evaporative vs air-cooled condensers, approach temperature, king valves, pressure relief valves, ASME/IIAR requirements, sight glasses, and charge level diagnostics.

Purging

Non-condensable buildup, purger operation, water-trap vents, verification of purger activity, and chronic non-condensable ingress diagnosis.

12%

Safety, Hazards, and Prevention

OSHA PSM (1910.119), EPA RMP (40 CFR 68), IIAR 2/6/7/9, SDS, HazCom/GHS, LOTO (1910.147), IDLH/PEL/STEL, SCBA use, first aid for ammonia exposure, ammonia detectors, ventilation, ESD, and pipe labeling.

How to Pass the RETA CARO Exam

What You Need to Know

Passing score: 70 (minimum passing score)
Assessment: Single exam, 110 multiple-choice questions
Time limit: 3 hours
Exam fee: $560 non-member / $390 RETA member

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

RETA CARO Study Tips from Top Performers

1Memorize the vapor-compression cycle end-to-end and learn to redraw it with real-world values: typical suction/discharge pressures, saturation temperatures for ammonia, and where subcooling and superheat happen.

2Practice reading ammonia saturated pressure/temperature tables. Know that -40 F ammonia is under vacuum and that a facility running below 0 psig risks air in-leakage and non-condensables.

3Study the ammonia SDS in detail. Know NIOSH IDLH (300 ppm), OSHA PEL (50 ppm 8-hr TWA), ACGIH TLV-TWA (25 ppm) and STEL (35 ppm), odor threshold (5-50 ppm), LFL/UFL (15-28% in air), and recommended firefighting media (water fog, not CO2).

4Learn when to use a CO2 extinguisher and why it is not preferred for ammonia in confined spaces. The ammonia SDS is a typical CARO exam reference.

5Understand IIAR 2 (design), IIAR 6 (inspection/testing/maintenance), IIAR 7 (operating procedures), and IIAR 9 (minimum safety criteria for existing systems). Know the applicable code each covers.

6Review OSHA PSM (29 CFR 1910.119) and EPA RMP (40 CFR Part 68) - especially the 10,000-lb threshold for ammonia and MOC requirements.

7Drill compressor operation: suction/discharge valves, unloaders, slide-valve capacity control on screws, compression ratio, net oil pressure, and classic troubleshooting patterns (high discharge temp, liquid slugging, fouled condenser).

8Practice oil management scenarios: why ammonia oils are largely immiscible with liquid ammonia, why oil logs in low-side vessels, safe oil draining procedures, and symptoms of oil starvation.

Frequently Asked Questions

How many questions are on the RETA CARO exam and how long is the exam?

CARO consists of 110 multiple-choice questions with a 3-hour time limit, per RETA's CARO application handbook. You must answer at least 70 percent of the questions correctly (minimum passing score of 70) to pass.

Is there a work-experience requirement to take CARO?

No. RETA states there are no minimum experience requirements for the CARO exam. CARO is the entry-level credential and is designed to confirm that an operator has the basic knowledge to function safely in an engine room under the supervision of a more experienced operator.

How much does the RETA CARO exam cost?

Per RETA's CARO application, the exam fee is $390 for RETA members and $560 for non-members. The retesting fee is $260 for members and $365 for non-members. Fees are subject to change on the RETA store; always verify the current fee at reta.com before applying.

Where do I take the RETA CARO exam?

CARO is a computer-based test administered through the Kryterion Testing Network (KTN) at more than 400 community colleges, universities, and training centers in the U.S., plus RETA Network Test Centers. RETA also offers Online Proctored (OLP) testing on a candidate's personal computer with an approved webcam.

What topics does the CARO exam cover?

RETA's CARO content outline covers refrigeration fundamentals (11%), refrigeration cycle (9%), properties of refrigerants (8%), saturated refrigerant tables (2%), types of compressors (2%), operation and maintenance of compressors (13%), lubrication (16%), evaporators and cooling units (9%), condensers and high-pressure receivers (11%), purging (4%), and safety/hazards/prevention (10%).

What is the best way to prepare for RETA CARO?

RETA publishes its own Industrial Refrigeration I and Basic Electricity I (safety only) texts and a downloadable CARO Study Guide with reference material that appears on-screen during the test. Many candidates also use RETA's paid Practice Test, IIAR's Ammonia Data Book and ANSI/IIAR 2, 6, 7, and 9 standards, plus hands-on operating experience.

How often do I need to recertify the RETA CARO credential?

RETA certifications must be recertified every three years. CARO recertification requires accumulating the required Professional Development Hours (PDHs) in refrigeration operation, service, repair, maintenance, or engineering, or by retaking the current CARO examination if PDHs are insufficient.

Is CARO a substitute for CIRO?

No. CARO is designed for assistant-level operators working under supervision. To supervise refrigeration system operations, candidates should pursue the Certified Industrial Refrigeration Operator (CIRO) credential, which requires two years of industrial refrigeration experience plus passing the CIRO exam.