What is a common characteristic of combustible liquids?

Combustible liquids are defined by their ability to give off flammable vapors at normal temperatures, which can lead to ignition under specific conditions. This characteristic distinguishes them from non-combustible liquids or those with higher flash points that do not easily produce vapors that can ignite.

The process of evaporation allows these liquids to release vapors into the air, and if the concentration of these vapors is within the flammable range when they encounter an ignition source, a fire can occur. This characteristic makes combustibility a significant concern for safety in environments where these liquids are present.

Flash points, the temperature at which a liquid can form flammable vapors, can vary among combustible liquids, but they are typically not classified as high compared to non-combustible substances. Environments do not need to be under high pressure for combustion to occur, nor do combustible liquids imply any particular level of toxicity. Thus, the ability to emit flammable vapors at normal temperatures is the defining feature of combustible liquids.