CNG - Compressed Natural Gas Codes, Standards, and Compliance Questions and Answers

Question 1

A maintenance facility that services CNG-powered vehicles must comply with specific ventilation and heating requirements outlined in NFPA 30A.
Which of the following combinations is compliant for a major repair area?

Accepted Answer

A mechanical ventilation system interlocked with a gas detection system and a heater with surfaces below 750°F.

Answer

A natural ventilation system and a direct-fired gas heater.

Answer

An open-flame radiant tube heater and manually operated roof vents.

Answer

A ventilation rate of 0.5 cfm/sqft and any UL-listed heating system.

Question 2

According to CSA/ANSI NGV 2, the standard for CNG vehicle fuel containers, which piece of information is NOT required to be on the cylinder's permanent label?

Accepted Answer

The name of the original vehicle installer.

Answer

The container's date of manufacture (month and year).

Answer

The service pressure and the symbol 'DOT'.

Answer

The container designation (e.g., Type 1, 2, 3, or 4).

Question 3

A technician is performing a compliant defueling of a CNG vehicle's cylinders before a major repair. According to NFPA 52 and industry best practices, where should this procedure be performed?

Accepted Answer

Outdoors, away from ignition sources, with the vehicle properly grounded.

Answer

Inside a repair bay with the garage doors open.

Answer

In a designated indoor defueling booth with explosion-proof lighting.

Answer

Anywhere in the facility as long as a portable vent stack is used.

Question 4

A CNG-powered truck with a GVWR of 26,000 lbs is involved in a collision resulting in significant damage to the truck bed, but no visible impact to the fuel cylinders or lines. According to FMVSS 304, what is the mandatory action regarding the CNG fuel system?

Accepted Answer

A detailed visual inspection by a qualified inspector is required before the vehicle is returned to service.

Answer

If the pressure gauge reads normal, no inspection is needed.

Answer

The driver can perform a cursory visual inspection before returning to service.

Answer

Continue normal operation until the next scheduled 12-month inspection.

Question 5

The design and compatibility of CNG fueling nozzles and vehicle receptacles, which prevent a vehicle from being filled at a pressure higher than its rating, are governed by which standard?

Accepted Answer

CSA/ANSI NGV 1

Answer

NFPA 30A

Answer

FMVSS 304

Answer

CSA/ANSI NGV 2

Question 6

A technician is installing an EPA-certified aftermarket CNG conversion system on a 2022 light-duty truck. Which label is the technician required to affix in a conspicuous location in the engine compartment?

Accepted Answer

A supplemental emission control information label.

Answer

A red triangular CNG decal.

Answer

An alterer's label next to the driver-side door jamb.

Answer

A cylinder hydrostatic test date sticker.