Gas Fitter Class A Licensing Exam

Gas Fitter Class A Licensing Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a gas regulator in a natural gas

system?

a) Increase gas pressure

b) Reduce and maintain pressure at a safe level

c) Filter gas impurities

d) Measure gas volume

Correct Answer: b

Rationale: Regulators are designed to reduce incoming high pressure

to a controlled, safe working pressure.

• Which gas is the primary component of natural gas?

a) Ethane

b) Propane 1 / 3

c) Butane

d) Methane

Rationale: Natural gas consists of approximately 85–95% methane.

• Which unit is commonly used to measure gas pressure in distribution

systems?

• mmHg
• psig
• kW

d) Amps

Rationale: Pounds per square inch gauge is a standard for gas

pressure measurements.

4. The upper explosive limit (UEL) of natural gas is approximately:

• 2%
• 5%
• 15%
• 30%

Rationale: Natural gas has a flammable range of about 5%–15% in

air; 15% is the UEL.

5. Odorant is added to natural gas to:

a) Improve combustion

b) Change density

c) Enable leak detection 2 / 3

d) Increase luminosity of flame

Rationale: Mercaptan odorants assist in identifying leaks by smell.

6. Propane vapor is:

a) Lighter than air

b) Same weight as air

c) Heavier than air

d) Non-combustible

Rationale: Propane vapor sinks and can accumulate in low areas

posing hazard.

• A Class A Gas Fitter is permitted to work on appliances with input

ratings:

a) Below 400,000 BTU

b) Any residential units only

c) Unlimited BTU capacity

d) Portable equipment only

Rationale: Class A certification allows work on any gas-fired

equipment without limit.

8. Combustion air must provide sufficient:

a) Fuel supply

b) Oxygen for complete combustion

c) Exhaust pressure

d) Heat exchange

• / 3