CNG Vehicle Conversion and Installation 2

Question 1

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

Accepted Answer

FMVSS 303

Answer

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

Question 2

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

Accepted Answer

No detectable leakage at operating pressure

Answer

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

Question 3

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

Accepted Answer

Fuel pressure regulator

Answer

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.

Question 4

A Type 4 CNG cylinder is constructed of:

Accepted Answer

Full carbon fiber overwrap on a polymer liner

Answer

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

Question 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?

Accepted Answer

8 times in all directions

Answer

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

(CNG) Compressed Natural Gas Practice Test

(CNG) Compressed Natural Gas Practice Test

CNG Vehicle Conversion and Installation 2