There are two slogans at the gas station: "Please turn off the engine to refuel" and "Please don't use the mobile phone". This requirement is for fire prevention, because gasoline is easy at room temperature (). Gasoline is a colorless to yellowish flowable liquid. The boiling point range is about 30℃~ 205℃, and it can be gasified at room temperature. When the gas content is 74 ~ 123 g/m3, it will explode in case of fire. The main component is hydrocarbons with 4 to 12 carbons. Flammable.

When using a mobile phone, its internal circuit may produce a very small spark discharge when working. At this time, it is very easy to ignite gasified gasoline in the air and cause a fire.

So turn off the engine when you refuel, and don't use your cell phone. So as not to cause a fire.