Practice Test Geeks(CNG) Compressed Natural Gas Practice Test
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Fuel System Components 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 Fuel System Components flashcards as text

  1. A Type 4 CNG cylinder is constructed from:

    Answer: Plastic liner fully wrapped with carbon fiber composite

    Type 4 cylinders use a high-density polyethylene (HDPE) or nylon plastic liner that is completely overwrapped with carbon fiber composite for maximum strength at minimum weight.

  2. What is the standard service life of most Type 3 and Type 4 CNG cylinders in the US?

    Answer: 20 years

    FMVSS 304 and NGV2 standards typically allow CNG cylinders a 20-year or 15-year service life depending on cylinder type and manufacturer specifications.

  3. The CNG excess flow valve closes automatically when:

    Answer: Gas flow exceeds a preset rate due to a downstream leak or rupture

    The excess flow valve senses abnormally high flow caused by a broken line or fitting and shuts off to prevent rapid uncontrolled gas release.

  4. Why are CNG fuel system components required to be electrically bonded?

    Answer: To prevent static electricity buildup that could ignite gas

    Electrical bonding provides a continuous conductive path so that static charges dissipate safely rather than sparking in the presence of natural gas.

  5. Which valve on a CNG cylinder prevents gas from flowing backward from the system into the filling nozzle during fueling?

    Answer: Check valve

    The check valve allows gas to flow only one direction—into the cylinder—and prevents backflow toward the dispensing equipment when the nozzle is disconnected.

  6. At what pressure are most light-duty CNG vehicle cylinders typically rated for service in the US?

    Answer: 3,600 psi

    US light-duty CNG vehicles use cylinders rated at 3,600 psi (248 bar) service pressure, which is the standard for the NGV2 and equivalent standards.

  7. What is the purpose of the odorant injection system in a CNG vehicle fuel system?

    Answer: To add a detectable scent so leaks can be identified by smell

    Natural gas is naturally odorless, so mercaptan odorant is added at the distribution level to give it a distinctive smell that makes leaks detectable.