It is the chemical chain reaction in between of oxygen and combustible material or vaporous fuel ( solid : wood , liquid : petrol ) . To keep on the process of oxidation produces heat and light . This fact is know as FIRE
Fire needs 3 things to exist :
- Four different class of FUEL :
- A : wood , paper , cloth
- B : flammable liquid , oil
- C : Gasoline gas , hydrogen gas , butan
- D : Potassium , sodium , aluminum
- E : Electrical equipment
- F : Cooking oil
” IT’S MAKE FIRE TRIANGLE “For the purpose of extinguishers work , first need to know a little bit about fire .
Four things must be present at the same time in order to make flame .
1. Enough oxygen to sustain combustion .
2. Enough heat to raise to material to its ignition temperature .
3. Some sort of fuel , chemical and exothermic reaction that is flame .
** Essentially , extinguishers put out flame by taking away one or more elements of the fire triangle . **
In a typically wood fire :
When the wood reaches about 150 degrees Celsius , the heat decomposes some of the cellulose material that makes up the wood.
Some of the decomposed material is released as volatile gases. We know these gases as smoke. Smoke is compounds of hydrogen, carbon and oxygen. The rest of the material forms pure carbon, and ash, which is all of the nonburnable minerals in the wood .
The actual burning of wood then happens in two separate reactions:
- When the volatile gases are hot about 260 degrees C for wood , the compound molecules break apart, and the atoms recombine with the oxygen to form water, carbon dioxide and other products. In other words, they burn.
- The carbon in the char combines with oxygen as well, and this is a much slower reaction.
As they heat up, the rising carbon atoms (as well as atoms of other material) give out light. This “heat produces light” effect is called incandescence, and it is the same kind of thing that creates light in a light bulb. It is what causes the visible flame. Flame color varies depending on what you’re burning and how hot it is. Color variation within in a flame is caused by gases . Typically, the hottest part of a flame — the base — glows blue, and the cooler parts at the top glow orange or yellow.
The air we breathe is about 21% oxygen , it needs only 16% oxygen .
The energy necessary to increase the temperature of fuel to where sufficient vapors are given off for ignition to occur .