Red Seal Interprovincial Examination Gasfitter
Class A Practice Exam Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a gas pressure regulator?
A) Increase gas pressure to appliances
B) Maintain a constant gas pressure C) Shut off gas automatically
in case of leaks
D) Filter impurities from gas
Rationale: A gas pressure regulator maintains a consistent gas pressure
to ensure appliances operate safely and efficiently.
2. Which of the following gases is considered combustible?
A) Carbon dioxide
B) Nitrogen
C) Propane D) Helium
Rationale: Propane is a combustible gas commonly used in heating and
industrial applications.
3. What is the maximum allowable working pressure for a residential
gas piping system?
A) 50 kPa B) 14 kPa
C) 100 kPa
D) 200 kPa
,Rationale: Residential gas systems are typically designed for low
pressure, usually around 14 kPa (2 psi).
4. Which device prevents reverse flow of gas in a piping system?
A) Pressure relief valve
B) Check valve C) Backflow preventer
D) Regulator
Rationale: Backflow preventers or check valves are installed to stop
reverse flow and prevent contamination.
5. What is the main function of a gas meter?
A) Reduce gas pressure
B) Filter gas C) Measure gas consumption
D) Shut off gas supply automatically
Rationale: Gas meters measure the amount of gas used by a building for
billing and monitoring purposes.
6. When testing a gas system for leaks, which method is
recommended?
A) Open flame
B) Soap solution
C) High voltage testing
D) Compressed air only
Rationale: A soap solution produces bubbles at leak points and is safe
for detecting gas leaks.
7. Which of the following is a sign of incomplete combustion?
A) Blue flame
B) Steady flame C) Yellow flame
D) Silent flame
, Rationale: Yellow flames indicate incomplete combustion, which can
produce carbon monoxide.
8. What type of regulator is used for high-pressure gas cylinders?
A) Low-pressure regulator
B) High-pressure regulator
C) Backflow regulator
D) Flow restrictor
Rationale: High-pressure regulators reduce cylinder pressure to a safe,
usable level for equipment.
9. Which safety device shuts off gas flow when pilot flame goes out?
A) Relief valve
B) Pressure gauge C) Thermocouple
D) Flow restrictor
Rationale: A thermocouple senses the pilot flame and shuts off gas if the
flame is extinguished to prevent gas buildup.
10. What is the purpose of a vent in a gas appliance?
A) Increase gas pressure
B) Remove combustion products
C) Reduce gas flow
D) Filter incoming gas
Rationale: Vents carry harmful combustion gases safely outside the
building.
11. Which schedule of piping is commonly used for residential
gas supply?
A) Schedule 5
Class A Practice Exam Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a gas pressure regulator?
A) Increase gas pressure to appliances
B) Maintain a constant gas pressure C) Shut off gas automatically
in case of leaks
D) Filter impurities from gas
Rationale: A gas pressure regulator maintains a consistent gas pressure
to ensure appliances operate safely and efficiently.
2. Which of the following gases is considered combustible?
A) Carbon dioxide
B) Nitrogen
C) Propane D) Helium
Rationale: Propane is a combustible gas commonly used in heating and
industrial applications.
3. What is the maximum allowable working pressure for a residential
gas piping system?
A) 50 kPa B) 14 kPa
C) 100 kPa
D) 200 kPa
,Rationale: Residential gas systems are typically designed for low
pressure, usually around 14 kPa (2 psi).
4. Which device prevents reverse flow of gas in a piping system?
A) Pressure relief valve
B) Check valve C) Backflow preventer
D) Regulator
Rationale: Backflow preventers or check valves are installed to stop
reverse flow and prevent contamination.
5. What is the main function of a gas meter?
A) Reduce gas pressure
B) Filter gas C) Measure gas consumption
D) Shut off gas supply automatically
Rationale: Gas meters measure the amount of gas used by a building for
billing and monitoring purposes.
6. When testing a gas system for leaks, which method is
recommended?
A) Open flame
B) Soap solution
C) High voltage testing
D) Compressed air only
Rationale: A soap solution produces bubbles at leak points and is safe
for detecting gas leaks.
7. Which of the following is a sign of incomplete combustion?
A) Blue flame
B) Steady flame C) Yellow flame
D) Silent flame
, Rationale: Yellow flames indicate incomplete combustion, which can
produce carbon monoxide.
8. What type of regulator is used for high-pressure gas cylinders?
A) Low-pressure regulator
B) High-pressure regulator
C) Backflow regulator
D) Flow restrictor
Rationale: High-pressure regulators reduce cylinder pressure to a safe,
usable level for equipment.
9. Which safety device shuts off gas flow when pilot flame goes out?
A) Relief valve
B) Pressure gauge C) Thermocouple
D) Flow restrictor
Rationale: A thermocouple senses the pilot flame and shuts off gas if the
flame is extinguished to prevent gas buildup.
10. What is the purpose of a vent in a gas appliance?
A) Increase gas pressure
B) Remove combustion products
C) Reduce gas flow
D) Filter incoming gas
Rationale: Vents carry harmful combustion gases safely outside the
building.
11. Which schedule of piping is commonly used for residential
gas supply?
A) Schedule 5
