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Vehicle Conversion and Installation Flashcards

7 cards from real CNG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Vehicle Conversion and Installation flashcards as text

  1. Which federal standard governs the design and installation of CNG fuel systems on motor vehicles in the United States?

    Answer: FMVSS 303

    FMVSS 303 (Federal Motor Vehicle Safety Standard 303) sets requirements for CNG fuel system integrity on motor vehicles.

  2. What is the maximum allowable leakage rate for a CNG fuel system during a post-installation leak test per NFPA 52?

    Answer: No detectable leakage at operating pressure

    NFPA 52 requires that no detectable leakage be present when the system is tested at operating pressure.

  3. When converting a gasoline vehicle to CNG, which component must be upgraded to handle the higher fuel pressure?

    Answer: Fuel pressure regulator

    The fuel pressure regulator must reduce high-pressure CNG (up to 3,600 psi) to the lower pressure required by the engine's fuel injection system.

  4. A Type 4 CNG cylinder is constructed of:

    Answer: Full carbon fiber overwrap on a polymer liner

    Type 4 cylinders use a thermoplastic polymer liner fully wrapped with carbon fiber composite, making them the lightest cylinder type.

  5. During a CNG vehicle conversion, the installer must verify that the CNG cylinder mounting brackets can withstand a static load of at least how many times the cylinder's weight?

    Answer: 8 times in all directions

    NFPA 52 requires that cylinder mounting must withstand 8 times the cylinder weight in all directions to ensure crash safety.

  6. Which type of sealant is prohibited when assembling CNG fuel line fittings?

    Answer: Petroleum-based thread sealant (pipe dope)

    Petroleum-based thread sealants can swell or deteriorate in CNG service and are not compatible; only CNG-rated sealants or PTFE tape should be used.

  7. What is the primary purpose of the Manual Shutoff Valve (MSV) required on every CNG cylinder?

    Answer: To allow the fuel supply to be isolated manually during maintenance or emergencies

    The MSV provides a means to manually stop gas flow from the cylinder, which is essential for safe maintenance and emergency shutoff.