Licensing Exam Class A Practice Exam

Gas Fitter Natural Gas & Propane Licensing Exam Class A Practice Exam 100 Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary component of natural gas used in fuel-burning

systems?

• Ethane
• Propane
• Methane
• Butane

Rationale: Methane typically makes up 85–95% of natural gas.

2. Propane is stored as:

• A compressed solid
• A liquefied gas under pressure 1 / 3

• A vapor at atmospheric pressure
• A dissolved gas

Rationale: Propane becomes a liquid when pressurized for efficient

storage.

3. The ignition temperature of natural gas is approximately:

A. 300°C

B. 450°C

C. 540°C

D. 700°C

Rationale: Methane ignites at ~540°C.

• Which standard governs gas installation codes in North America?

A. NEC

B. OSHA 1910

C. CSA B149

D. NFPA 70E

Rationale: CSA B149 regulates gas appliances and installations.

• Which gas is heavier than air?
• Natural gas
• Propane
• Methane
• Hydrogen

Rationale: Propane has higher vapor density and accumulates low

areas. 2 / 3

6. Manifold pressure for most natural gas appliances is typically:

• 1 in. w.c.
• 3.5 in. w.c.
• 7 in. w.c.
• 14 in. w.c.

Rationale: Common pressure for NG appliance burners is 3.5" water

column.

7. An odorant added to natural gas is usually:

• Chlorine
• Mercaptan
• Ammonia
• Sulfuric acid

Rationale: Mercaptan provides recognizable “rotten egg” smell.

8. The primary function of a regulator is to:

• Increase line pressure
• Filter impurities
• Maintain consistent delivery pressure
• Shut off flow during demand

Rationale: Regulators reduce and stabilize gas pressure.

9. Propane cylinders must be stored:

• Indoors only
• Upright and secured outdoors
• Laid horizontally
• / 3