i worked in a gas station in the 80's. a guy was pumping his gas with a cigarette, i asked him to put it out. he said he was a fuel engineer in the navy and a cigarette will not ignight gas. he then removed the nozzel from the tank and released a 4 foot diameter puddle on the ground. he then entered the circle and threw his cigarette right in the gas where he stood, and he was right no fire.