A vehicle will have trouble operating if the carburetor meters too much gasoline. This is referred to as a rich mixture, which is too concentrated for ignition by the spark plugs. Too little gasoline in a vehicle's carburetor is called a lean mixture, which is too diluted for ignition. The ignition temperature is the temperature required for a liquid to continue to emit vapors which can and sustain combustion. Gasoline will ignite when a heat source or electrical spark of at least 853 degrees comes in contact with it.
Vapor density is the weight of a vapor relative to the weight of air.
The vapor density of natural gas causes it to be lighter than air and will rise when exposed in the open. The vapor density of gasoline is heavier than air and will seek low points when it is exposed to the air. The vapors expand and suddenly the container will explode. Return to top of Flammable Substances Gasoline and Other Flammable Liquids and Gases Gasoline is the most common flammable liquid found in the home. Used carelessly or improperly, it is the main cause of burn injuries among teenage boys.