Emergency Procedures and Response Flashcards

What is the flammability range of natural gas in air?

Answer: 5–15% by volume

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

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

Answer: Shut off the engine and exit the vehicle

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

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

Answer: Near the ceiling

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

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

Answer: Rotten eggs or sulfur

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

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

Answer: CNG disperses upward rather than pooling on the ground

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

Which fire extinguisher class is appropriate for a natural gas (CNG) fire?

Answer: Class B

CNG fires are classified as Class B (flammable gas) fires, which are addressed with CO2, dry chemical, or similar agents.

Upon detecting a natural gas odor inside a building, you should:

Answer: Evacuate immediately without operating any electrical switches

Electrical switches can generate sparks that may ignite accumulated gas; immediate evacuation without activating any device is essential.