Gas Fitter Class B Licensing Exam Practice

Gas Fitter Class B Licensing Exam Practice Exam 100 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?
• Measure gas usage
• Reduce and control gas pressure
• Filter out gas contaminants
• Provide emergency shutoff

Rationale: Regulators reduce high supply pressure to safe appliance

operating pressure.

• Which gas is primarily distributed in most residential systems?
• Propane
• Natural gas
• Butane
• Methane liquid 1 / 3

Rationale: Natural gas (mostly methane) is the standard fuel for residential

distribution.

• What odorant is added to natural gas for leak detection?
• Benzene
• Ammonia
• Mercaptan
• Carbon dioxide

Rationale: Mercaptan gives natural gas a sulfur smell for safety.

4. Typical manifold pressure for natural gas appliances is:

• 14" w.c.
• 3.5" w.c.
• 7" w.c.
• 2 psi

Rationale: Most natural gas appliances operate at 3.5" water column.

5. Propane is:

• Lighter than air
• Heavier than air
• Same density as air
• Odorless and safe

Rationale: Propane sinks to low areas creating greater explosion risk.

6. LPG cylinders must be stored: 2 / 3

• Indoors
• Outdoors and upright
• Next to ignition sources
• Below grade level

Rationale: Storage upright outdoors prevents liquid release and vapor

pooling.

7. The primary combustion products of natural gas are:

• CO₂, CO, sulfur
• Hydrogen, CO
• CO₂ and water vapor
• Nitrogen and oxygen

Rationale: Complete combustion yields water vapor and carbon dioxide.

8. Incomplete combustion results in increased:

• Oxygen
• Nitrogen
• Carbon monoxide
• Helium

Rationale: Lack of oxygen produces CO, a deadly gas.

• Which instrument is used to detect gas leaks?
• Thermocouple
• Electronic combustible gas detector
• Voltmeter
• / 3