Why does fire happen

Fire

Mastery of Fire

Even a small carelessness in dealing with fire can endanger human life and wreak havoc.

Man did not invent fire, but discovered it as a means of use for himself. It helped him to make a huge evolutionary leap many millennia ago.

Humans learned to deal with fire and recognized its usefulness: It lit up the darkness, protected him from the cold and animals, helped him to prepare his food in an edible and digestible way, and destroyed epidemic waste. With the help of the fire, he was able to live in regions where he would otherwise hardly have survived.

Some finds indicate that our ancestors - more precisely: Homo erectus - already used the power of fire around 1.5 million years ago. But the question of when humans were able to ignite fires on their own is still hotly debated among researchers. Many believe that the Neanderthals were able to do this with the help of flint stones 40,000 years ago.

What is fire and how does it come about?

You need three things for a fire: fuel, heat and oxygen. In the heat, the fuel reacts with the oxygen in the air, causing oxidation. This means that the molecules of the fuel combine with the oxygen and heat is released in the process. Fire is what is known as an exothermic reaction: it produces more heat than is needed to start the reaction.

To start a fire, you need an initial ignition or starting heat, which starts the chemical combustion process of the fuel and continues in a kind of chain reaction. An initial spark in nature can, for example, be lightning striking a tree.

The starting heat creates the flame, and the resulting heat sets a chain reaction in motion: The fire now burns out of itself until one of the three things - fuel, heat or oxygen - is no longer there.

Erasure methods

Once a fire has started, it can quickly get out of control and assume life-threatening proportions for humans within a few minutes. In order to put out a fire, you only have to remove either the heat, the fuel or the oxygen. Sounds very easy.

But the extinguishing method depends on the burning materials. The best extinguishing agent is still water: it is cheap, environmentally friendly and almost everywhere in unlimited quantities. In the event of a fire, it is used either as a thick extinguishing jet or as a rain of droplets.

If you spray water on something that is burning, energy is withdrawn from the flame - until there is not enough energy left to heat the fire together with fuel and oxygen. For example, if water is sprayed onto a piece of glowing charcoal, the fuel, coal, cools down more and more.

In addition, steam is generated, which rises - another extinguishing effect: the steam becomes a barrier that reduces the supply of oxygen. The flame gets smaller until it finally goes out. That is, water quenches because it's cool, not because it's wet.

But there are also fires that should never be extinguished with water: for example, liquid fires. Small or even larger explosions can occur here. In the case of grease fires, jet flames meters high can arise: The water droplets penetrate the hot liquid and evaporate in fractions of a second, expanding greatly.

This tears fuel particles into the air, which explode immediately on contact with the oxygen in the air. Liquid fires are extinguished with foam. This separates the fuel from the oxygen. Extinguishing gas should be used wherever there are materials such as computers. A grease fire in the pan can be extinguished by simply placing a lid on the pan. This takes the air out of the fire.

Fire protection in the household

A fire in the household can be kindled quickly. A burning cigarette falls on the floor, children light a fire with matches, an outdated electronic device causes a smoldering fire or a cable fire. But despite the high risk of fire in the household, fire extinguishers are not always to hand. Often they are completely absent, out of date or poorly maintained.

Existing devices should be checked by a specialist every two years, devices that are more than 20 years old should be replaced with new ones. The fire extinguisher should be installed in such a way that it is quickly accessible, for example in the hallway or entrance area. Pictograms printed on the bottle provide information about the fire classes for which the fire extinguisher is suitable.

Fire class A, for example, are solid materials such as wood, paper or textiles, fire class D metals such as aluminum or lithium. It is important to be familiar with the handling of a fire extinguisher as far as possible before an emergency occurs. Because only small fires can be completely extinguished with it, so timely use is important.

Fires often break out at night and the victims are surprised in their sleep. Often those affected become unconscious from the carbon monoxide before they wake up from coughing and do not die from the flames, but from the effects of smoke inhalation. Smoke alarms can therefore be lifesavers.

Most of the smoke detectors available on the market work optically and emit a shrill signal tone as soon as smoke particles enter their measuring chambers. In order to be protected even in the event of a power failure, the devices should be battery-operated. There are special thermal detectors for the kitchen that react to heat instead of steam in order to avoid frequent false alarms.