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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. What action must a CNG conversion installer take if they discover the vehicle's original equipment manufacturer (OEM) warranty may be affected by the conversion?

    Answer: Disclose this to the vehicle owner in writing before beginning work

    Installers are required to inform vehicle owners in writing about potential impacts on the OEM warranty before performing conversion work.

  2. Which organization issues the certifications most commonly required for technicians who perform CNG vehicle conversions in the United States?

    Answer: Natural Gas Vehicle Institute (NGVi)

    NGVi offers the industry-standard training and certification program for CNG vehicle conversion technicians in the US.

  3. What is the correct response when a CNG fuel line fitting shows frost or ice formation during vehicle operation in warm weather?

    Answer: Shut down the vehicle immediately — frost indicates a rapid pressure drop from a leak or restriction

    Frost on a CNG fitting in warm ambient temperatures indicates Joule-Thomson cooling from a gas leak, which is a serious safety emergency.

  4. The CNG fueling receptacle on a converted vehicle must be located in a position that:

    Answer: Is accessible from outside the vehicle and away from ignition sources, exhaust, and electrical components

    NFPA 52 specifies that the fill receptacle must be externally accessible and separated from ignition sources, exhaust, and electrical systems.

  5. A CNG conversion's high-pressure solenoid valve fails in the open position. What is the most immediate safety concern?

    Answer: Uncontrolled gas flow to the engine and potential over-fueling or fuel release

    A solenoid stuck open allows continuous high-pressure gas flow, which can cause over-fueling, dangerous emissions, or fuel release if downstream components also fail.

  6. Under NFPA 52, when must a CNG cylinder be hydrostatically retested?

    Answer: Cylinders certified to NGV-2 standard are not retested; they are retired at end of service life

    NGV-2 certified cylinders used in vehicles have a defined service life and are removed from service rather than retested, unlike industrial cylinders.

  7. Which action is required before welding or cutting on a vehicle within 18 inches of a CNG system component?

    Answer: Depressurize and purge the CNG system and remove or shield cylinders

    All CNG components near hot work must be fully depressurized, purged of gas, and removed or properly shielded to prevent ignition of residual gas.