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Quizzes > Science

RMGA Practice Test: Gas Technician Exam Prep

Quick, free gas technician practice test with instant results.

Editorial: Review CompletedCreated By: Brooke HanlonUpdated Aug 24, 2025
Difficulty: Moderate
Questions: 20
Learning OutcomesStudy Material
Paper art representing a quiz on Gas Technician Certification Practice Exam

This RMGA practice test helps you check your readiness for the gas technician certification exam, focusing on safety, codes, and troubleshooting. Answer 15 multiple-choice questions and get instant results with brief explanations. For more hands-on review, try the gas safety inspection quiz and the hvac quiz.

What is the primary function of a gas pressure regulator?
To reduce and control downstream gas pressure
To ignite the gas in the appliance
To prevent backflow of gas
To measure gas flow rate
A gas pressure regulator lowers high supply pressure to a controlled, usable level for appliances. It ensures stable downstream pressure regardless of upstream fluctuations.
Which instrument is commonly used to measure gas pressure in inches of water column?
Manometer
Barometer
Anemometer
Flowmeter
A manometer directly measures pressure in inches of water column, which is the standard unit for low-pressure gas systems. Barometers measure atmospheric pressure, not low gas pressures.
What is the standard nominal supply pressure for natural gas residential appliances in the U.S.?
2 psi
7 inches water column
4 psi
14 inches water column
Residential natural gas appliances in the U.S. are typically designed to operate at 7 inches water column (approximately 0.25 psi). This nominal pressure ensures consistent performance.
Which color coding is typically used for natural gas piping?
Red
Green
Blue
Yellow
Yellow is the standard color code for natural gas piping to provide clear visual identification. Other colors are used for different utilities or fluids.
What is the simplest method to detect a small gas leak around a joint?
Rely solely on smell
Use a magnet
Inspect with an infrared camera
Apply a soap and water solution
Applying a soap solution to joints and watching for bubbles is a simple, reliable way to detect small gas leaks. Infrared cameras are more advanced and magnets are not used for leak detection.
In a gas piping system, if the inlet pressure is 7 inches WC and the outlet needs 4 inches WC, what is the required pressure drop across the regulator?
7 inches WC
3 inches WC
1 inch WC
11 inches WC
The pressure drop is simply the difference between inlet and desired outlet pressures: 7 inches WC minus 4 inches WC equals a 3-inch WC drop. Regulators are selected accordingly.
What NFPA standard specifically covers the installation of fuel gas piping systems?
NFPA 72
NFPA 58
NFPA 54
NFPA 70
NFPA 54, also known as the National Fuel Gas Code, governs the installation and operation of fuel gas piping systems. NFPA 70 covers electrical standards.
A balanced flue system differs from a natural draft venting system by:
Requiring a manual vent damper
Relying solely on chimney draft
Operating only at atmospheric pressure
Using both intake and exhaust in concentric pipes
Balanced flue systems draw combustion air and expel exhaust through concentric pipes, isolating the appliance from room air. Natural draft vents rely on thermal buoyancy in a chimney.
When performing a combustion analysis, which gas is most indicative of incomplete combustion?
Carbon dioxide
Carbon monoxide
Oxygen
Nitrogen
Carbon monoxide is produced when fuel does not burn completely. High CO levels in flue gas signal poor combustion and potential safety hazards.
If a pilot burner flame is lifting and causing soot, what is a likely cause?
Cold draft conditions
Insufficient combustion air
Blocked vent
Excessive gas pressure
A lifting flame often occurs when gas pressure is too high, pushing the flame off the burner head and causing soot. Adjusting to correct pressure restores proper flame shape.
According to typical code, vent termination must be at least how many feet from any building opening into the building?
10 feet
6 inches
3 feet
1 foot
Codes generally require vent outlets to be at least 3 feet from windows, doors, or other openings to prevent flue gases from entering the building.
When sizing a gas pipe, which factor is NOT required?
Material of pipe
Diameter
Type of gas
Color of paint
Paint color does not affect gas flow or pressure drop calculations. Sizing requires gas type, pipe material, length, diameter, and allowable pressure drop.
A technician notes a CO level of 400 ppm in flue gas. What is the immediate action?
Open the combustion chamber
Shut down the appliance and ventilate
Increase gas pressure
Adjust the air shutter
A CO reading of 400 ppm is dangerously high, requiring immediate shutdown and ventilation. Adjustments should only resume after identifying the combustion issue.
What device prevents regulator failure in the event of diaphragm rupture?
Check valve
Relief valve
Vent damper
Pilot light
A relief valve vents excess pressure if the diaphragm ruptures, protecting downstream appliances. Without it, unsafe high pressure could reach the system.
When calculating gas flow, the standard cubic feet per hour (SCFH) accounts for:
Only temperature correction
Standard temperature and pressure conditions
Only pressure correction
Only volume at current conditions
SCFH normalizes gas volume to a standard reference temperature and pressure, allowing accurate comparisons and calculations.
Given a series piping layout with three appliances requiring 40, 60, and 80 CFH respectively, what total capacity must the main supply line support?
80 CFH
60 CFH
40 CFH
180 CFH
In a series layout, the main line must supply the sum of individual demands: 40 + 60 + 80 equals 180 CFH. This ensures all appliances can operate simultaneously.
A gas appliance requiring 150 CFH at 7 inches WC is fed through 50 feet of pipe that has a pressure drop rate of 0.04 inches WC per 100 CFH per foot. What is the approximate pressure drop through the pipe?
0.3 inches WC
3 inches WC
15 inches WC
7 inches WC
Calculate drop: 0.04" WC Ã- (150 CFH/100) Ã- 50 ft = 3" WC. This shows the impact of flow rate and length on pressure loss.
For a Category I furnace with an input of 120,000 BTU/hr using single-wall galvanized vent, what minimum vent diameter is required by code?
12 inches
6 inches
3 inches
9 inches
Code tables specify a 6-inch single-wall vent for Category I furnaces up to 120,000 BTU/hr. Undersizing can cause poor draft and combustion issues.
In a direct vent appliance, why is concentric vent pipe used?
To avoid corrosion in the vent
For electrical bonding purposes
To save material cost
To prevent pressure imbalance and ensure sealed combustion
Concentric vent pipes separate intake and exhaust flows, maintaining balanced pressures and a sealed combustion environment. This enhances safety and efficiency.
When diagnosing a furnace fault that indicates the pressure switch is open, which of the following is a likely cause?
Gas regulator malfunction
Blocked vent or inducer fan failure
Thermostat wiring error
Dirty flame sensor
An open pressure switch often signals inadequate draft, commonly due to a blocked vent or a failed inducer motor. This prevents the switch from sensing proper negative pressure.
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Learning Outcomes

  1. Analyze gas system diagrams and identify component functions.
  2. Evaluate pressure and flow calculations for safe installation.
  3. Apply safety protocols in gas leak detection and prevention.
  4. Identify regulatory standards for gas technician certification.
  5. Demonstrate proper venting and combustion analysis procedures.
  6. Master troubleshooting techniques for gas equipment malfunctions.

Cheat Sheet

  1. Understand Gas System Components - Dive into gas system diagrams like a detective on a quest, spotting regulators, meters, and valves. Knowing what each part does makes troubleshooting feel like solving a fun puzzle.
  2. Master Pressure and Flow Calculations - Get your inner scientist excited by calculating pressure drops and flow rates to ensure safe installations. Perfecting formulas like the Ideal Gas Law (PV=nRT) feels like mastering a magic spell in your own lab.
  3. Implement Gas Leak Detection Protocols - Become a gas leak detective using sniffer tools, soapy-water tests, and safety drills. Regular inspections will keep you one step ahead of sneaky leaks and help everyone breathe easy.
  4. Know Regulatory Standards - Dive into NFPA codes like they're the rulebook for your favorite strategy game - compliance is the ultimate winning move. Following these standards ensures you stay within the legal playground and keep operations safe.
  5. Practice Venting and Combustion Analysis - Master venting techniques and flue gas checks so appliances can breathe easy and burn clean. Analyzing combustion feels like reading a secret code hidden in the smoke.
  6. Develop Troubleshooting Skills - Solve pilot light mysteries and burner hiccups with a systematic detective mindset. Each successfully diagnosed fault feels like unlocking a new level of expertise.
  7. Understand Gas Properties - Learn the personality of natural gas - flammability limits, energy content, and more - to handle it safely and smartly. This foundational knowledge transforms you into a confident gas guru.
  8. Learn Emergency Procedures - Be the hero in gas emergencies with clear shutdown and evacuation moves. Fast, informed actions can turn potential chaos into calm and keep everyone safe.
  9. Study Pipe Sizing and Material Selection - Choose the perfect pipe size and material like picking the right tool for a boss battle. Proper selection prevents leaks, maintains pressure, and keeps the system running smoothly.
  10. Review Combustion Efficiency Testing - Boost appliance performance with combustion efficiency tests that check Oâ‚‚ and COâ‚‚ levels. Think of it as tuning a race car for peak performance with minimal emissions.
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