During fueling, which fuel property contributes most to fire risk?

• A. Volatility
• B. Viscosity
• C. Color
• D. Odor

Answer: (A)

Volatility is the key factor because it describes how readily a fuel forms vapors at ambient temperatures. During fueling, fuels with high volatility release more vapors into the air, creating a flammable vapor cloud. That vapor can ignite if it encounters an ignition source such as a static discharge, a spark from equipment, or a hot surface, leading to a fire or flash fire near the fueling area. The more vapors produced, the greater the fire risk.

Viscosity affects how the liquid flows and how fuel is pumped and handled; it doesn’t directly determine how much vapor is produced. Color has no reliable link to flammability or fire risk, and odor is not a dependable indicator of ignition danger—odors can be present without a significant vapor concentration, and some fuels are odorless.