Gas Fitter Licensing Practice Exam

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

• What is the primary code used for gas fitting installations in North

America?

A. NFPA 72

• NFPA 54 (National Fuel Gas Code)

C. NFPA 58

D. ASME B31.1

 NFPA 54 governs the installation and operation of fuel gas piping systems and appliances.*

2. The specific gravity of natural gas is approximately:

A. 1.0 1 / 4

B. 0.8

C. 0.6

D. 1.2

 Natural gas is lighter than air with a specific gravity of about 0.6, allowing it to rise when leaked.*

3. The minimum burial depth for underground gas piping in most codes is:

• 6 inches
• 12 inches
• 18 inches
• 24 inches

 Most codes require 18 inches of cover to protect gas piping from physical damage.*

4. When pressure testing a new gas piping system, air should not be used if:

• The system is less than ½ psi
• The piping is for fuel gas service
• The system is indoors
• The piping is small diameter

 Using air is prohibited in some jurisdictions due to explosion risk; inert gases like nitrogen are safer.*

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5. The color of gas piping for identification purposes is typically:

• Blue
• Yellow
• Red
• Green

 Yellow is the standard color for fuel gas lines for easy recognition and safety.*

6. The main regulator at the gas meter reduces pressure from:

• Inches of water column to inches of mercury
• Pounds per square inch (psi) to inches of water column
• Inches of mercury to psi
• Atmospheres to psi

 Service regulators reduce high distribution pressures to appliance- level pressures, typically 7” w.c.*

• Which instrument is used to measure gas pressure in inches of water

column?

• Thermocouple
• Manometer
• Barometer
• Pressure gauge 3 / 4

 A manometer measures low gas pressures in inches of water column.*

8. Combustion requires fuel, heat, and:

• Nitrogen
• Oxygen
• Carbon
• Pressure

 The fire triangle includes fuel, heat, and oxygen.*

9. Incomplete combustion of natural gas produces:

A. CO₂

B. H₂O

• CO (Carbon Monoxide)

D. CH₄

 Incomplete combustion forms toxic carbon monoxide due to lack of sufficient oxygen.*

• The flue gas temperature of a Category I natural draft appliance is

generally:

• Above dew point of flue gases
• Below dew point
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