Ontario Refrigeration Operator Class
B Exam (TSSA) Questions And
Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which type of refrigerant is commonly used in low-pressure
chillers?
a) R-134a
b) R-410A
c) Ammonia (R-717)
d) R-22
Rationale:
Ammonia is widely used in industrial low-pressure refrigeration systems
due to its high efficiency and suitability for large-capacity chillers.
2. The primary function of a condenser in a refrigeration system is to:
a) Evaporate refrigerant
b) Reject heat from the refrigerant to the surroundings
c) Compress the refrigerant
d) Absorb heat from the refrigerated space
Rationale:
The condenser removes heat absorbed by the refrigerant in the
evaporator and compressor, releasing it to air or water.
3. Which safety device is used to prevent overpressure in a
refrigeration system?
,a) Thermostat
b) Flow switch
c) Pressure relief valve
d) Expansion valve
Rationale:
Pressure relief valves protect the system from pressures exceeding
design limits, preventing potential explosions or damage.
4. In ammonia refrigeration, which material is commonly used for
piping?
a) Copper
b) PVC
c) Steel
d) Aluminum
Rationale:
Ammonia is highly reactive with copper and aluminum; steel is
preferred for its compatibility and strength.
5. Superheat refers to:
a) Temperature of refrigerant at condenser exit
b) Temperature of vapor refrigerant above its saturation point at
the evaporator exit
c) Pressure at the compressor inlet
d) Temperature of refrigerant in the liquid line
Rationale:
Superheat ensures that only vapor enters the compressor, preventing
liquid slugging and damage.
6. Subcooling in a refrigeration system:
a) Reduces the temperature of liquid refrigerant below its saturation
temperature
,b) Increases evaporator pressure
c) Increases compressor suction
d) Reduces condenser efficiency
Rationale:
Subcooling increases system efficiency and ensures the refrigerant
entering the expansion device is fully liquid.
7. Which of the following is a low-pressure refrigerant?
a) R-134a
b) Ammonia (R-717)
c) R-410A
d) R-404A
Rationale:
Ammonia systems operate at low pressures compared to modern HFC
refrigerants, making them suitable for large chillers.
8. What is the purpose of an expansion valve in a refrigeration
system?
a) Compress refrigerant
b) Condense refrigerant
c) Control refrigerant flow and reduce pressure before entering the
evaporator
d) Measure refrigerant temperature
Rationale:
The expansion valve meters refrigerant into the evaporator at the correct
pressure and rate to optimize cooling.
9. Which type of compressor is most commonly used in large
industrial ammonia systems?
a) Reciprocating
b) Rotary
, c) Scroll
d) Screw
Rationale:
Screw compressors are efficient for high-capacity ammonia systems and
provide continuous, reliable operation.
10. Which instrument is commonly used to measure refrigerant
pressure?
a) Thermometer
b) Hygrometer
c) Manifold gauge set
d) Anemometer
Answer: C
Rationale:
A manifold gauge set measures both high-side and low-side system
pressures, making it essential for diagnosing refrigeration system
performance.
11. What is the primary purpose of compressor oil in a refrigeration
system?
a) Increase refrigerant pressure
b) Lubricate moving parts and reduce wear
c) Lower condenser temperature
d) Improve refrigerant purity
Answer: B
B Exam (TSSA) Questions And
Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which type of refrigerant is commonly used in low-pressure
chillers?
a) R-134a
b) R-410A
c) Ammonia (R-717)
d) R-22
Rationale:
Ammonia is widely used in industrial low-pressure refrigeration systems
due to its high efficiency and suitability for large-capacity chillers.
2. The primary function of a condenser in a refrigeration system is to:
a) Evaporate refrigerant
b) Reject heat from the refrigerant to the surroundings
c) Compress the refrigerant
d) Absorb heat from the refrigerated space
Rationale:
The condenser removes heat absorbed by the refrigerant in the
evaporator and compressor, releasing it to air or water.
3. Which safety device is used to prevent overpressure in a
refrigeration system?
,a) Thermostat
b) Flow switch
c) Pressure relief valve
d) Expansion valve
Rationale:
Pressure relief valves protect the system from pressures exceeding
design limits, preventing potential explosions or damage.
4. In ammonia refrigeration, which material is commonly used for
piping?
a) Copper
b) PVC
c) Steel
d) Aluminum
Rationale:
Ammonia is highly reactive with copper and aluminum; steel is
preferred for its compatibility and strength.
5. Superheat refers to:
a) Temperature of refrigerant at condenser exit
b) Temperature of vapor refrigerant above its saturation point at
the evaporator exit
c) Pressure at the compressor inlet
d) Temperature of refrigerant in the liquid line
Rationale:
Superheat ensures that only vapor enters the compressor, preventing
liquid slugging and damage.
6. Subcooling in a refrigeration system:
a) Reduces the temperature of liquid refrigerant below its saturation
temperature
,b) Increases evaporator pressure
c) Increases compressor suction
d) Reduces condenser efficiency
Rationale:
Subcooling increases system efficiency and ensures the refrigerant
entering the expansion device is fully liquid.
7. Which of the following is a low-pressure refrigerant?
a) R-134a
b) Ammonia (R-717)
c) R-410A
d) R-404A
Rationale:
Ammonia systems operate at low pressures compared to modern HFC
refrigerants, making them suitable for large chillers.
8. What is the purpose of an expansion valve in a refrigeration
system?
a) Compress refrigerant
b) Condense refrigerant
c) Control refrigerant flow and reduce pressure before entering the
evaporator
d) Measure refrigerant temperature
Rationale:
The expansion valve meters refrigerant into the evaporator at the correct
pressure and rate to optimize cooling.
9. Which type of compressor is most commonly used in large
industrial ammonia systems?
a) Reciprocating
b) Rotary
, c) Scroll
d) Screw
Rationale:
Screw compressors are efficient for high-capacity ammonia systems and
provide continuous, reliable operation.
10. Which instrument is commonly used to measure refrigerant
pressure?
a) Thermometer
b) Hygrometer
c) Manifold gauge set
d) Anemometer
Answer: C
Rationale:
A manifold gauge set measures both high-side and low-side system
pressures, making it essential for diagnosing refrigeration system
performance.
11. What is the primary purpose of compressor oil in a refrigeration
system?
a) Increase refrigerant pressure
b) Lubricate moving parts and reduce wear
c) Lower condenser temperature
d) Improve refrigerant purity
Answer: B
