Is water flammable or flammable

Department of biology, chemistry, pharmacy

Some lighter fluid is placed in a beaker and ignited. The flame cannot be extinguished by splashing or dousing.

The gasoline floats burning on the beaker and sets a much larger area on fire when the beaker is full and overflows.

If you repeat the experiment, but this time spray the water with a flower sprayer into the fire, it will go out immediately.

The sprayed water droplets no longer get under the gasoline, but evaporate beforehand in the hot flame zone. But water in particular needs a lot of energy to evaporate, which it draws from the fire. In addition, every small droplet pops up into a much larger water vapor bubble. Both - cooling and displacement of the air causes the flame to extinguish.

learning goals

Liquids that are not miscible with water cannot be extinguished with water. Hydrocarbons are lighter than water. They swim up there and continue to burn there. This explains the news spread by oil tankers in the event of accidents. The water spray has a much better extinguishing effect and is widely used. Examples are:

  • Sprinkler systems
  • Fire fighting (e.g. forest fires) from the air.
  • The fire brigade also uses water in a spray jet and no longer in "C-pipes".

In spite of this, incipient fires are better fought with fire extinguishers. Fire extinguishers of fire class "B" can basically be used for all flammable solvents. Extinguishing high-boiling, burning liquids with water results in a fat explosion. Even if the burning liquid is miscible with water, extinguishing it with water can be ineffective, because various solvents, e.g. acetone or ethanol, are still flammable even in highly diluted form.