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Ontario Refrigeration Operator Class B Certification
Exam | Latest Verified Questions and Detailed Answers
OVERVIEW DESCRIPTION:
This comprehensive set of multiple-choice questions is designed for the Ontario
Refrigeration Operator Class B certification exam, based on TSSA (Technical Standards and
Safety Authority) requirements and the PanGlobal Refrigeration Plant Operator
curriculum. The questions cover essential topics including system components
(compressors, evaporators, condensers, expansion valves), refrigerants (R-717, R-744,
HFCs, HCFCs), safety controls, pressure vessels, thermodynamics (superheat, subcooling,
compression ratio), psychrometrics, cooling towers, water treatment, electrical controls
(VFDs, safety switches), codes (CSA B52), and operational best practices.
QUESTION 1
What is the minimum required operating experience in a Class A or B refrigeration plant
to challenge the TSSA Refrigeration Operator Class B exam?
A) 720 hours
B) 1,440 hours
C) 2,160 hours
D) 3,000 hours
CORRECT ANSWER: B
EXPERT RATIONALE: TSSA guidelines require 1,440 hours of practical training in a Class
A or B refrigeration plant to qualify for the Class B certification exam.
QUESTION 2
Which code governs the mechanical safety requirements for the design, construction,
installation, and inspection of refrigeration systems in Ontario?
A) CSA B51
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B) CSA B52
C) ASHRAE 15
D) CSA B149.3
CORRECT ANSWER: B
EXPERT RATIONALE: CSA B52: Mechanical Refrigeration Code sets the standards for
safety in refrigeration systems, while CSA B51 covers boilers and pressure vessels .
QUESTION 3
A refrigeration system uses R-717. What safety property is most critical for the operator
to monitor?
A) Its high global warming potential
B) Its toxicity and flammability
C) Its low odor detection threshold
D) Its high miscibility with oil
CORRECT ANSWER: B
EXPERT RATIONALE: R-717 (Ammonia) is classified as a B2L refrigerant, meaning it has
high toxicity and moderate flammability, requiring specific safety protocols.
QUESTION 4
What is the primary purpose of a purge unit on a low-pressure chiller?
A) To remove non-condensable gases from the condenser
B) To lubricate the compressor bearings during startup
C) To prevent the evaporator from freezing
D) To recover refrigerant for recharging
CORRECT ANSWER: A
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EXPERT RATIONALE: Purge units remove air and other non-condensables that enter the
low-pressure side of a chiller, improving efficiency and preventing corrosion.
QUESTION 5
Which component directly follows the evaporator in a basic mechanical compression
refrigeration cycle?
A) Expansion valve
B) Compressor
C) Condenser
D) Receiver
CORRECT ANSWER: B
EXPERT RATIONALE: The compressor draws in low-pressure, low-temperature refrigerant
vapor from the evaporator and compresses it to a high-pressure, high-temperature gas.
QUESTION 6
What is the function of a low-pressure cutout switch?
A) To start the condenser fan motor
B) To stop the compressor if suction pressure falls too low
C) To regulate the flow of refrigerant to the evaporator
D) To bypass the expansion valve during defrost
CORRECT ANSWER: B
EXPERT RATIONALE: The low-pressure cutout is a safety control that shuts down the
compressor to prevent damage from loss of refrigerant charge or a blocked suction line.
QUESTION 7
A shell-and-tube evaporator is used for cooling water. To prevent damage from
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freezing, what must the operator ensure?
A) The condenser water flow is never interrupted
B) The refrigerant charge is exactly at the design level
C) Adequate water flow is maintained when the chiller is running
D) The oil separator is operating at maximum efficiency
CORRECT ANSWER: C
EXPERT RATIONALE: Freezing occurs when water temperature drops below 0°C.
Maintaining proper water flow prevents localized freezing and potential tube rupture.
QUESTION 8
In a psychrometric chart, what does the wet-bulb temperature line represent?
A) Sensible heat only
B) Total heat (enthalpy) of the air mixture
C) The partial pressure of the refrigerant
D) The specific volume of dry air
CORRECT ANSWER: B
EXPERT RATIONALE: Wet-bulb temperature is a measure of the enthalpy of the air,
combining both sensible and latent heat, and is used for cooling tower and evaporative
cooling design .
QUESTION 9
What is the typical consequence of oil logging in an evaporator?
A) Increased system efficiency
B) Reduced heat transfer capacity
C) Compressor motor over-amping
D) High discharge pressure trips
Ontario Refrigeration Operator Class B Certification
Exam | Latest Verified Questions and Detailed Answers
OVERVIEW DESCRIPTION:
This comprehensive set of multiple-choice questions is designed for the Ontario
Refrigeration Operator Class B certification exam, based on TSSA (Technical Standards and
Safety Authority) requirements and the PanGlobal Refrigeration Plant Operator
curriculum. The questions cover essential topics including system components
(compressors, evaporators, condensers, expansion valves), refrigerants (R-717, R-744,
HFCs, HCFCs), safety controls, pressure vessels, thermodynamics (superheat, subcooling,
compression ratio), psychrometrics, cooling towers, water treatment, electrical controls
(VFDs, safety switches), codes (CSA B52), and operational best practices.
QUESTION 1
What is the minimum required operating experience in a Class A or B refrigeration plant
to challenge the TSSA Refrigeration Operator Class B exam?
A) 720 hours
B) 1,440 hours
C) 2,160 hours
D) 3,000 hours
CORRECT ANSWER: B
EXPERT RATIONALE: TSSA guidelines require 1,440 hours of practical training in a Class
A or B refrigeration plant to qualify for the Class B certification exam.
QUESTION 2
Which code governs the mechanical safety requirements for the design, construction,
installation, and inspection of refrigeration systems in Ontario?
A) CSA B51
,2|Page
B) CSA B52
C) ASHRAE 15
D) CSA B149.3
CORRECT ANSWER: B
EXPERT RATIONALE: CSA B52: Mechanical Refrigeration Code sets the standards for
safety in refrigeration systems, while CSA B51 covers boilers and pressure vessels .
QUESTION 3
A refrigeration system uses R-717. What safety property is most critical for the operator
to monitor?
A) Its high global warming potential
B) Its toxicity and flammability
C) Its low odor detection threshold
D) Its high miscibility with oil
CORRECT ANSWER: B
EXPERT RATIONALE: R-717 (Ammonia) is classified as a B2L refrigerant, meaning it has
high toxicity and moderate flammability, requiring specific safety protocols.
QUESTION 4
What is the primary purpose of a purge unit on a low-pressure chiller?
A) To remove non-condensable gases from the condenser
B) To lubricate the compressor bearings during startup
C) To prevent the evaporator from freezing
D) To recover refrigerant for recharging
CORRECT ANSWER: A
,3|Page
EXPERT RATIONALE: Purge units remove air and other non-condensables that enter the
low-pressure side of a chiller, improving efficiency and preventing corrosion.
QUESTION 5
Which component directly follows the evaporator in a basic mechanical compression
refrigeration cycle?
A) Expansion valve
B) Compressor
C) Condenser
D) Receiver
CORRECT ANSWER: B
EXPERT RATIONALE: The compressor draws in low-pressure, low-temperature refrigerant
vapor from the evaporator and compresses it to a high-pressure, high-temperature gas.
QUESTION 6
What is the function of a low-pressure cutout switch?
A) To start the condenser fan motor
B) To stop the compressor if suction pressure falls too low
C) To regulate the flow of refrigerant to the evaporator
D) To bypass the expansion valve during defrost
CORRECT ANSWER: B
EXPERT RATIONALE: The low-pressure cutout is a safety control that shuts down the
compressor to prevent damage from loss of refrigerant charge or a blocked suction line.
QUESTION 7
A shell-and-tube evaporator is used for cooling water. To prevent damage from
, 4|Page
freezing, what must the operator ensure?
A) The condenser water flow is never interrupted
B) The refrigerant charge is exactly at the design level
C) Adequate water flow is maintained when the chiller is running
D) The oil separator is operating at maximum efficiency
CORRECT ANSWER: C
EXPERT RATIONALE: Freezing occurs when water temperature drops below 0°C.
Maintaining proper water flow prevents localized freezing and potential tube rupture.
QUESTION 8
In a psychrometric chart, what does the wet-bulb temperature line represent?
A) Sensible heat only
B) Total heat (enthalpy) of the air mixture
C) The partial pressure of the refrigerant
D) The specific volume of dry air
CORRECT ANSWER: B
EXPERT RATIONALE: Wet-bulb temperature is a measure of the enthalpy of the air,
combining both sensible and latent heat, and is used for cooling tower and evaporative
cooling design .
QUESTION 9
What is the typical consequence of oil logging in an evaporator?
A) Increased system efficiency
B) Reduced heat transfer capacity
C) Compressor motor over-amping
D) High discharge pressure trips
