CNG Emergency Procedures and Response 2

Question 1

What is the flammability range of natural gas in air?

Accepted Answer

5–15% by volume

Answer

Natural gas is flammable only when its concentration in air falls between approximately 5% and 15% by volume.

Question 2

When a CNG leak is detected inside a vehicle, what is the FIRST action the driver should take?

Accepted Answer

Shut off the engine and exit the vehicle

Answer

Shutting off the engine eliminates a major ignition source, and immediately exiting removes personnel from the hazard zone.

Question 3

In an enclosed building, released CNG will tend to accumulate:

Accepted Answer

Near the ceiling

Answer

Natural gas (methane) is lighter than air, causing it to rise and collect at ceiling level in enclosed spaces.

Question 4

The odorant added to natural gas to assist in leak detection smells like:

Accepted Answer

Rotten eggs or sulfur

Answer

Mercaptan (ethyl mercaptan) is added to odorless natural gas and produces a distinctive rotten egg or sulfur odor.

Question 5

Compared to a gasoline spill, an outdoor CNG release is generally safer because:

Accepted Answer

CNG disperses upward rather than pooling on the ground

Answer

Being lighter than air, CNG rises and dilutes in the atmosphere instead of forming a ground-level liquid pool that can spread fire.

(CNG) Compressed Natural Gas Practice Test