Fueling Station Operations Flashcards

If a CNG fire ignites at a fueling station, what is the FIRST recommended action?

Answer: Activate the emergency fuel shutoff and evacuate the area

The first priority in a CNG fire is activating the emergency shutoff to cut fuel supply, followed by immediate evacuation and calling 911 — extinguishing a gas fire without stopping flow creates an explosive cloud.

What is the lower explosive limit (LEL) of natural gas (methane) in air?

Answer: 5%

Methane's LEL is approximately 5% by volume in air; below this concentration, the mixture is too lean to ignite.

Which NFPA code is the primary national standard for CNG vehicular fueling system safety?

Answer: NFPA 52

NFPA 52, Vehicular Natural Gas Fuel Systems Code, is the primary standard covering CNG fueling station design, installation, and operational safety.

At what percentage of the LEL should a fixed combustible gas detector alarm at a CNG station?

Answer: 20% LEL

Industry practice sets alarm thresholds at 20% LEL to provide early warning well before gas concentrations reach an ignitable range.

What type of portable fire extinguisher is most appropriate for use at a CNG fueling station?

Answer: Dry chemical ABC-rated extinguisher

ABC dry chemical extinguishers are appropriate at CNG stations because they handle ordinary combustibles, flammable gases/liquids, and energized electrical equipment.

What is the correct action if a CNG dispenser hose coupling begins leaking during an active fueling operation?

Answer: Stop fueling immediately and depressurize the hose before inspecting

A leaking coupling requires an immediate fueling stop and full hose depressurization before any inspection or repair is attempted.

Under NFPA 52, what is the minimum required distance between a CNG dispenser and a building opening (door, window, or air intake)?

Answer: 10 feet

NFPA 52 requires CNG dispensers to be located at least 10 feet from building openings to prevent gas accumulation inside structures.